Dissertations / Theses: 'Ore deposition'

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Spencer, Edward. "The transport and deposition of molybdenum in porphyry ore systems." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/27402.

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Approximately 99% of Mo is obtained from porphyry deposits (e.g. Sillitoe, 2010), representing the strongest association of any metal with a single deposit type. Despite this, the controls on the formation of Mo-rich porphyries and the spatial-temporal decoupling of Mo from Cu in these systems remain poorly understood. By combining fieldwork, Re-Os molybdenite dating and a fluid inclusion study at one of the world's largest Cu-Mo porphyries (El Teniente, Chile), this project assesses the magmatic-hydrothermal evolution of the system to help constrain the processes controlling Mo enrichment. Results indicate that deposit-wide Mo grades of < 0.06 wt.% are principally controlled by the abundance of main mineralisation-type quartz-molybdenite veins, that develop outwards and upwards into Cu-rich vein types. Parental ore fluids had low salinities (~6.5 wt.% NaCleq) and were exsolved at depth following the emplacement of multiple intrusions that acted as short-lived (< 100,000 years) conduits for mineralising fluids between 6.3 and 4.6 Ma. The decoupled deposition of Mo and Cu surrounding each temporally separate intrusion is attributed to the sequential deposition of Mo then Cu in response to decreasing temperature followed by intermittent fluid boiling and increasing fluid pH in response to sericitic alteration of the mafic host-rocks. Mo grades > 0.06 wt.% correspond to the presence of late mineralisation-type veins and breccias produced by the exsolution of Mo-rich brines ±aqueous fluids from a highly fractionated magma source. Mineralisation in this stage was short-lived and occurred in all parts of the deposit at ~4.6 Ma. The relatively Cu-poor nature of this stage is attributed to the prior preferential extraction of Cu from the underlying magma chamber in earlier mineralising events. In accordance with data from other Mo-rich porphyry systems, results indicate that Mo-Cu decoupling is controlled by both changes in magma chemistry as well as by the evolving P-T-X properties of hydrothermal fluids.

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Archibald, Sandy M. "The role of vapour in the transport and deposition of metals in ore-forming systems /." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82821.

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The solubility of gold and copper chloride in liquid-undersaturated, HCl-bearing water vapour was investigated experimentally at elevated temperatures and pressures. Experimental results show that the solubility of gold and copper is significant, increasing at higher fHCl and fH2O for gold, and at higher fH2O for copper. These increases are attributed to the formation of hydrated gas species, with a metal:chlorine ratio of 1. Hydration numbers vary from 5 at 300°C to 3 at 360°C for gold, and from 7.6 at 280°C, to 6.0 at 300°C, and 6.1 at 320°C for copper; the results reflect the presence of trimer [Cu3Cl3•(H2O)n] or tetramer [Cu4Cl4•(H2O)n] species. Results indicate that solubility for both vapour species is retrograde, i.e., it decreases with increasing temperature, and formed via the reactions: Ausolid+m·HClgas+n·H2 Ogas=AuClm·H2 Ogasn+m 2·Hgas2 3CuClsolid+n·H2Ogas= Cu3Cl3·H2O gasn
Calculations based on the solubility data indicate an economic high-sulphidation Au deposit (e.g., Nansatsu, Japan; 36 tonnes) could form in ~30,000 years, whereas a porphyry copper deposit (e.g., 50 million tonnes at 0.5% Cu) could form in as little as ~20,500 years, assuming transport only in the vapour phase.
Precious- and base-metal-rich composite scales, containing up to 111 ppm Au and 628 ppm Ag, occur in surface pipes at the Momotombo geothermal field, Nicaragua. Polysulphide scale fragments, comprising chalcopyrite, sphalerite, galena, electrum and hessite grains in a matrix of amorphous silica, formed as a result of cooling and ligand loss induced by boiling, during fluid ascent in well MT-36. Secondary bornite, stromeyerite and chalcocite/digenite replaced chalcopyrite through the addition of Cu and Ag and an increase in fO2 . A drop in pH due to well closure resulted in replacement of primary and secondary sulphides by tetrahedrite.
Reaction-path modelling using the program CHILLER simulates deposition of minerals from the reconstructed deep geothermal fluid, at temperature intervals (depths) along excess enthalpy and isoenthalpic boiling paths. These simulations accurately reproduce the paragenetic sequence of base- and precious-metal mineralization in the scales. The modelling indicates excess enthalpy boiling results in metal precipitation at greater depths than would be expected for isoenthalpic boiling, and that at Momotombo this occurs through the destabilisation of bisulphide complexes in response to loss of CO2 and H2 S during phase separation.

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Törmänen, T. (Tuomo). "Ore mineralogy, geochemistry, and formation of the sediment-hosted sea floor massive sulfide deposits at Escanaba Trough, NE Pacific, with emphasis on the transport and deposition of gold." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514276264.

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Abstract Recent sea floor sulfide deposits form when seawater, heated within the oceanic crust, discharges to the sea floor. Upon mixing with cold seawater, sulfide-forming elements such as sulfur, iron, copper, and zinc are precipitated from the fluid. Actively forming sea floor massive sulfide deposits are found from different lithologic and tectonic environments varying from mid-ocean ridges to back-arc spreading centers. At a few localities, sulfide deposits are associated with turbiditic sediments that cover the axial valley of the spreading center. The southern part (Escanaba Trough) of the Gorda Ridge (NE Pacific) is one such example. At Escanaba Trough, massive sulfide deposits are associated with small sediment hills, which were uplifted by the intrusion of sills and laccoliths within the sediments. Hydrothermal deposits are dominated by pyrrhotite-rich massive sulfides, with subordinate amounts of sulfate-rich precipitates and polymetallic sulfides. Compared to deposits hosted by volcanites, Escanaba Trough sulfides contain relatively low amounts of copper and zinc. However, the average gold concentration is relatively high for a sediment-hosted deposit, and is comparable with other, Au-enriched, sea floor sulfide deposits. Despite the relatively high Au concentration in many volcanic-hosted sea floor sulfide deposits, discrete Au grains are rare. They occur mostly with sphalerite, pyrite, chalcopyrite and tetrahedrite-tennantite. Sixteen of the pyrrhotite-rich samples from Escanaba Trough were found to contain visible Au grains. They occur mostly with native Bi and various BiTe phases, and to lesser degree, with Fe-Co sulfarsenides. Transport of Au in sea floor hydrothermal systems is attributed to the presence of Au(HS)2- complex, which is destabilized when the fluid mixes with seawater. Hydrothermal fluids are generally undersaturated with respect to Au complexes and additional mechanisms, such as remobilizing earlier precipitated Au is required to explain the high Au concentrations encountered in many deposits. At Escanaba Trough the mechanism is attributed to early precipitation of Bi as melt droplets, at temperatures greater its melting temperature, as liquid Bi is capable of collecting Au even from an undersaturated fluid. Upon cooling Au is exsolved from the Bi host as native Au or maldonite (Au2Bi).

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Gapara, Cornwell Sine. "A review of the deposition of iron-formation and genesis of the related iron ore deposits as a guide to exploration for Precambrian iron ore deposits in southern Africa." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005610.

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Iron-formations are ferruginous sedimentary rocks which have their source from fumarolic activity associated with submarine volcanism, with deposition of iron as oxides, hydroxides, and hydrous oxide-silicate minerals in shallow and/or deep marine sedimentary systems. The Precambrian ironformations of southern Africa have a wide age range, but are more prominently developed before 1.SGa. These iron formations occur in greenstone belts of the Kaapvaal and Zimbabwean cratons, in the Limpopo mobile belt, in cratonic basins and in the Damara mobile belt. The Archaean-Proterozoic sedimentary basins and greenstone belts host iron ore deposits in iron-formation. Iron formations have a lengthy geological history. Most were subjected to intense, and on occasions repeated, tectonic and metamorphic episodes which also included metasomatic processes at times to produce supergene/hypogene high grade iron ores. Iron-formations may be enriched by diagenetic, and metamorphic processes to produce concentrating-grade ironformations. Uplift, weathering and denudation, have influenced the mineral association and composition of the ores, within which magnetite, haematite and goethite constitute the major ore minerals. The iron resources of the southern Africa region include the Sishen deposits, hosting to about 1200 Mt of high grade direct shipping ore, at >63% Fe. Deposits of Zimbabwe have more than 33 000 Mt of beneficiable iron-formation. The evaluation of an iron ore prospect involves many factors which must be individually assessed in order to arrive at an estimate of the probable profitability of the deposit. Many of these are geological and are inherent in the deposit itself. Other factors are inherent aspects of the environment in which the ore is formed. Although the geological character of the ore does not change, technological advances in the processing techniques may have a great effect on the cost of putting the ore into marketable form. Geochemical, geophysical and remote sensing methods would be used for regional exploration. Chip sampling and drilling are useful for detailed exploration. Purely geological exploration techniques are applicable on a prospect scale in the exploration of iron ore deposits. Regional exploration targeting should choose late Archaean greenstone belts containing oxide facies iron-formation or Early Proterozoic basins located at craton margins as they are both known to host high-grade haematite orebodies formed by supergene/hypogene enrichment. Most types of iron ore deposits in southern Africa are described and classified. An attempt is made to emphasize the major controls on mineralisation, in the hope that these may be applicable to exploration both in the southern African region and within analogous settings around the world.

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Bouse, Robin Marie. "Lead isotopic compositions of ore deposition and their host rocks in Arizona: Implications for the crustal inheritance of metals." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187411.

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Pb isotopic compositions of twelve Late Cretaceous-Early Tertiary (LC-ET) igneous complexes in Arizona suggest that there are no isotopic distinctions between productive (those that host a porphyry copper deposit) and barren complexes. Pb isotopic compositions of the LC-ET igneous rocks are similar to those of the Proterozoic basement rocks in which they are located and indicate a regional coherence and inheritance of Pb isotopic compositions. Within the LC-ET igneous complexes, there is commonly a decreasing trend in 206Pb/204Pb from the oldest to youngest pluton. In Arizona, the sulfide mineralization in porphyry copper deposits is generally spatially and temporally associated with the youngest plutons. Pb isotopic compositions of the sulfide mineralization suggest that much of the mineralization was deposited from fluids with an isotopic composition similar to the plutons lowest in 206Pb/204Pb, (the younger plutons). The low 206Pb/204Pb values of the younger plutons and sulfide mineralization suggest derivation from a lower crustal source. Not all the sulfide mineralization has the same Pb isotopic composition. Some distal mineralization, later stage mineralization, and mineralization hosted in Precambrian rocks have Pb isotopic compositions higher in 206Pb/204Pb. The higher 206Pb/204Pb suggests that these mineralizing fluids interacted with upper crustal rocks. Ag/Au ratios of LC-ET igneous complexes and Middle to Late Tertiary metallic mineral districts in Arizona geographically correspond to Pb isotopic provinces. Pb isotopic compositions and model Th/U for sulfide mineralization from 50 of the metallic mineral districts mimic regional Pb isotopic trends defined by Early Proterozoic whole rocks. Crustal provinces with Th/U higher or lower than the crustal average (Th/U≅4) have a higher potential for Au-enriched ore deposits. Crustal provinces with Th/U≅4 have a higher potential for Ag-enriched ore deposits. The Pb isotopic data presented here are consistent with the crustal inheritance of metal ratios. Thus, the crustal inheritance hypothesis can be used as a viable exploration technique at the crustal-province scale. Mass spectrometers that also have the capability of rapid elemental analyses (ICPMS) and aeroradiometric data are useful tools for this exploration method.

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Bao, Zhiwei. "Geochemistry of the sediment-hosted disseminated gold deposits in Southwestern Guizhou Province, China." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2001. http://theses.uqac.ca.

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Polteau, Stéphane. "The early proterozoic Makganyene glacial event in South Africa : its implication in sequence stratigraphy interpretations, paleoenvironmental conditions and iron and manganese ore deposition." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1007612.

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The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup in the Griqualand West Basin. It consists of diamictites, sandstones, banded iron-formations (BIFs), shales, siltstones and carbonates. It is generally accepted that the Makganyene Formation rests on an erosive regional unconformity throughout the Northern Cape Province. However this study demonstrates that this stratigraphic relationship is not universal, and conformable contacts have been observed. One of the principal aims of this study is to identify the nature of the Makganyene basal contact throughout the Griqualand West Basin. Intensive fieldwork was carried out from Prieska in the south, to Danielskuil in the north. In the Sishen and Hotazel areas, only borehole material was available to assess the stratigraphy. The Griquatown Fault Zone delimits the boundary between the deep basin and platform facies. The Koegas Subgroup is only present south of the Griquatown Fault Zone, where it pinches out. However, the transition Griquatown BIFs-Koegas Subgroup occurs in lacustrine deposits on the Ghaap platform (Beukes, 1983). The Griquatown Fault Zone represents the edge of the basin, which corresponds to a hinge rather than a fault zone. The Makganyene Formation rests with a conformable contact on the Koegas Subgroup south of the Griquatown Hinge Zone, and north of it the Makganyene Formation lies unconformably on the Asbestos Hills Subgroup. The Makganyene Formation displays lateral facies changes that reflect the paleogeography of the Griqualand West Basin, and the development of ice sheets/shelves. The Ghaap platform is characterised by coarse immature sand interbedded with the diamictites. The clasts in this area contain local Asbestos Hills material and no dropstones are present. Such settings are typical of sediments that are being deposited below a grounded ice mass. At the Griquatown Hinge Zone, the sandstone lenses are smaller, and the clasts consist of chert, of which a great number are striated and faceted. In the Matsap area, the presence of dropstones is strong evidence for the presence of a floating ice shelf that released its material by basal melting. Further south, the Makganyene Formation contains stromatolitic bioherms that only form if clastic contamination is minimal and therefore the ice that transported the detritus to the basin did not extend far into open sea conditions. The base of the Hotazel Formation also contains diamictite levels. Dropstones have been identified, implying a glacial origin. The Hotazel diamictites are interbedded with hyaloclastites and BIFs. The Makganyene glacial event, therefore, was not restricted to the Makganyene Formation, but also included the Ongeluk Formation, through to the base of the Hotazel Formation. Petrographic studies of the Makganyene Formation and the base of the Hotazel Formation reveal mineral assemblages that are diagnostic of early to late diagenetic crystallisation and of low-grade metamorphism not exceeding the very low green-schist facies. The facies identified display the same sense of basin deepening, from shallow high-energy Hotazel area on the Ghaap platform, to the deep basin in the Matsap area. Whole-rock geochemical analyses reveal that the elemental composition of the Makganyene Formation is very similar to that of the Asbestos Hills BIFs, which were the most important source of clastic detritus for the Makganyene Formation. However, minor amounts of carbonates of the Campbellrand Subgroup, as well as a felsic crustal input from the Archean granitoid basement, made contributions. On the Ghaap platform, the Makganyene diamictite is enriched in iron, calcium, and magnesium, while in the deeper parts of the basin the diamictites are enriched in detrital elements, such as titanium and aluminium, which occur in the fine clay component. The Hotazel diamictite displays a distinct mafic volcanic input, related to the extrusion of the Ongeluk basaltic andesites, which was incorporated in the glacial sediments. Sequence stratigraphy is based on the recognition of contacts separating the different systems tracts that compose a depositional sequence. However, because the basal contact of the Makganyene Formation has not been properly identified in previous work, no correct model has been proposed so far. Therefore correlations between the Griqualand West and the Transvaal basins, based on lithostratigraphic similarities and extrapolations of unconformities, have to be reviewed, especially since the publication of new radiometric ages contradict all previously proposed correlations. It is proposed here that the Transvaal Supergroup in the Griqualand West Basin represents a continuous depositional event that lasted about 200 Ma. The Makganyene glacial event occurred during changing conditions in the chemistries of the atmosphere and ocean, and in the continental configuration. A Snowball Earth event has been proposed as the causative process of such paleoenvironmental changes. However, evidence presented here of less dramatic glacial conditions, with areas of ice-free waters, implies an alternative to the Snowball Earth event. The paleoenvironmental changes are thought to represent a transition from an anaerobic to aerobic atmosphere, that was responsible for the global cooling of the surface of the Earth, Such a glacial event may have aided in the large-scale precipitation of iron and manganese in areas of intense upwellings.

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Laurila, Tea Elisa. "The Metalliferous Sediments of the Atlantis II Deep (Red Sea)." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32229.

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The Atlantis II Deep is a location of modern submarine hydrothermal activity along the slowly spreading Red Sea rift axis. Venting of high-temperature hydrothermal fluids, similar to those associated with black smokers, takes place in a brine pool and has led to the accumulation of 90 Mt (dry, salt free) of stratiform, metalliferous sediment. The conditions of mineralization are unique in the modern oceans, but have been widely suggested as a possible analog of some important ancient stratiform base metal ore deposits. This study shows that many of the proposed genetic models for these ancient deposits may be highly simplified and do not take into account rapid diagenetic transformations, widespread non-equilibrium processes, and many other aspects of metal deposition. Sediment cores of the Atlantis II muds were last studied more than 30 years ago. High-resolution sampling and careful re-examination of the mineralogy and geochemistry of the sediments, using modern analytical techniques has significantly improved the understanding of the different processes responsible for the formation of the finely layered metallifeous sediments. The geochemistry of the individual layers is controlled by highly variable detrital, hydrogenic and hydrothermal input. Primary depositional pathways from the brine pool are the main control on basin-wide metal distribution (e.g., increasing Cu/Zn away from the vents) including variable enrichment in trace metals via scavenging from the brine pool and from the enriched pore waters. Cu and Zn have been deposited not only as sulfides but also with poorly crystalline Si-Fe-(oxy)hydroxides. A significant proportion of the original non-sulfide Cu and Zn are diagenetically transformed into sulfides, but also carbonates and clays, in large part reflecting sulfide deficient pore waters. Negative δ34S values, previously unrecognized in the sulfide- and metal-rich units, indicate a source of bacteriogenic sulfide. Syn-diagenetic processes also appear to have been responsible for the sharp laminations in the sediments, as well as distinctive zoning of carbonate and clay minerals around the vent source. The early diagenetic transformations observed in the Atlantis II Deep may not be preserved in the ancient rock record but nevertheless have important implications for metal deposition in some of the world’s largest and richest base metal ore deposits.

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Nilsson, Erik A. A. "Degradation Mechanisms of Heat Resistant Steel at Elevated Temperatures : In an Iron Ore Pelletizing Industry." Doctoral thesis, Luleå tekniska universitet, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62162.

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This thesis focuses on the different degradation mechanisms of the stainless steel in a travelling grate in a Grate-Kiln iron ore pellet indurator. The travelling grate is a conveyor belt that transports green-body pellets to a rotary kiln while the pellets are being dried and pre-heated to a temperature of 900-1100 °C by recycled hot air. After unloading of the pellets to the rotary-kiln for further sintering, the travelling grate is cooled in room temperature while returning to the loading zone of the wet pellets. The steel was tested during thermal cycling in a test-rig, in order to simulate the influence of thermo mechanical fatigue and oxide spallation. The influence of erosion-deposition was investigated in a modified horizontal industrial combustion kiln at 800 °C, with slag and coal from production used as erosive media and combustion fuel, respectively. The influence of minor alloying additions of Mn, Si and Ti on the microstructure was explored by eight different casted alloy compositions. Isothermal heat treatments were performed at 800 °C during 200 hours on steel immersed in deposits recovered from a travelling grate in production. The three main degradation mechanisms found in this work are thermal spallation, erosion-deposition and deposit induced accelerated corrosion (DIAC). Thermal spallation of the oxide layer is caused by the thermal expansion difference between the oxide and the metal during heating and cooling. It has been found that Ti improves the spallation resistance while Si reduces it. Spallation of deposits is another cause believed to increase the degradation. Erosion-deposition appears due to simultaneous erosion and deposition of particles on the travelling grate that causes erosion or deposition depending on the amount of alkali metals in the environment. The velocity of the particles also influences erosion and deposition in the way that higher velocities increase erosion. DIAC is proposed to form on the travelling grate due to the concentration of chloride- and sulphate containing alkali metals in the deposits. Other than these major degrading mechanisms, minor degradation mechanisms such as internal oxidation, sigma formation, carburization and sensitization towards inter-granular attack have been found inside the steel during heating. Thermo mechanical fatigue (TMF) causes intergranular cracks in the material of the travelling grate. Casting issues such as micro-segregation have also been addressed in this thesis. A few different ways to improve degradation resistance have been proposed, such as homogenization heat treatments, optimization of process parameters and inhibitor solutions.

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Stalder, Marcel. "Petrology and mineral chemistry of sulphide ores and associated metalliferous rocks of the Gamsberg Zn-Pb deposit, South Africa : implications for ore genesis and mineral exploration." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16072.

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Thesis (PhD)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: The Gamsberg Zn-Pb deposit is a metamorphosed and multiply deformed sediment-hosted base metal deposit in the central Namaqua Province of South Africa. The deposit is hosted by the Bushmanland Group, a late Palaeoproterozoic (2000-1600 Ma) supracrustal succession of quartzite, metapelitic schist and interbedded metavolcanic rocks. Mineralisation occurs within the central part of the Gams Formation, a heterogeneous sequence of metamorphosed metalliferous sediments and fine-grained organic-rich shales. The ore horizon is subdivided into a lower unit of metapelite-hosted ore, an intermediate layer of phosphorite-hosted ore, and an upper unit of banded garnet-apatite ore. The ore body is enveloped by unmineralised silicate-, carbonate- and oxide-facies metalliferous rocks, which originally represented mixtures of Fe-Mn-rich hydrothermal precipitates, authigenic carbonate, and variable concentrations of detrital material. Based on mineralogical and geochemical characteristics, the metalliferous host rocks are subdivided into iron formations, coticules, Fe-Mn silicates, impure marbles and barite/Ba-rich quartzite. Minerals of the Gams Formation mostly represent solid solution between the Fe and Mn end-members of garnet, pyroxene, pyroxenoid, amphibole, olivine, spinel and ilmenite. Calcium-rich rock types are a typical feature and characterized by the occurrence of manganoan calcite, clinopyroxene, andradite-rich garnet and titanite. A successive increase in the (Mn+Ca):Fe value of rocks and minerals is evident with increasing distance from the ore horizon. Amphibole is restricted to Fe-rich ore-bearing assemblages, whereas orthopyroxene, clinopyroxene, Fe-rich pyroxenoid and olivine are present in intermediate assemblages, and Mn-rich rhodonite and pyroxmangite in the most manganiferous assemblages. These variations are mimicked by an increase in the Mn:Fe value of coexisting garnet and ilmenite group minerals with increasing distance from ore. LA-ICP-MS analyses have been used to constrain the REE patterns of garnet and apatite. In the ore-body, these minerals display a positive Eu anomaly, which is interpreted to reflect a distinct hydrothermal signature. In contrast, garnet and apatite in unmineralised metalliferous rocks display nil or a negative Eu anomaly. Primary features of the Gams Formation, such as REE patterns, the banded nature of garnet-apatite ore, the presence of diagenetic apatite nodules, and the distribution of the redox-sensitive elements Ba and Mn have been used to constrain palaeo-environmental conditions. The results indicate that metapelitehosted ore has been deposited in a stratified ocean that was characterised by anoxic bottom waters and precipitation of Fe and Zn sulphides into organic matter-rich shales. These rocks were superceded by phosphorite-hosted ore, garnet-apatite ore and metalliferous host rocks that developed in a suboxic to oxic environment. The large size of the deposit, the internal lamination of the ores and the predominance of sphalerite and barite are consistent with a vent-distal setting and precipitation of the ore-forming constituents from dense and reduced hydrothermal fluids, which originated due to reactivation of dormant growth faults. Collectively, the geological evidence indicates that Gamsberg is bridging the gap betweenthe SEDEX and BHT classifications. The relationships demonstrate that differences between these two classes of sediment-hosted Zn-Pb deposits are predominantly related to environmental conditions within localised third order basins and not to fundamental differences in ore-forming processes.
AFRIKAANSE OPSOMMING: Die Gamsberg Zn-Pb afsetting is ‘n meerfasig vervormde en gemetamorfiseerde sedimentgesetelde onedel metaal afsetting in die sentrale Namakwa Provinsie van Suid Afrika. Die afsetting word geherberg deur die Boesmanland Groep, ‘n laat Paleoproterosoïse (2000 – 1600 Ma) bokors-opeenvolging van kwartsiet, metapelitiese skis en tussengelaagde metavulkaniese gesteente. Mineralisasie word gevind in the sentrale deel van die Gams Formasie. Die Gams Formasie is ‘n heterogene opeenvolging van gemetamorfiseerde metaalhoudende sediment en fynkorrelrige organiese skalie. Die erts horison word onderverdeel in ‘n onderste laag van metapeliet-gesetelde erts, n sentrale laag van fosforiet-gesetelde erts, en ‘n boonste laag van gebande granaat-apatiet erts. Die erts-liggaam word omhuls deur ongemineraliseerde silikaat-, karbonaat- en oksied-fasies metal-ryke rotse. Hierdie gesteentes word geinterpreteer as oorspronklike mengsels van Fe-Mn-ryke hidrotermale partikels, outigeniese karbonaat, en verskeie hoeveelhede detritale materiaal. Gebaseer op mineralogiese en geochemiese kenmerke word hierdie rotse onderverdeel in ysterformasies, „coticules“, Fe-Mn silikate, onsuiwer marmer en barite/Ba-ryke kwartsiet. Minerale van die Gams Formasie form meestal soliede oplossingsreekse tussen die Fe en Mn endlede van granaat, pirokseen, piroksenoid, amfibool, olivien, spinel en ilmeniet. Kalsium-ryke rots tipes is ‘n tipiese kenmerk van die Gams Formasie en word gekenmerk deur mangaan-ryke kalsiet, klinopirokseen, andradiet-ryke granaat en sfeen. Daar word ‘n stapsgewyse vergroting van die (Mn+Ca):Fe verhouding in gesteentes en minerale gevind met toeneemende afstand van die erts horison. Amfibool is beperk tot Fe-ryke ertsdraende gesteentes, ortopirokseen, klinopirokseen, Fe-ryke piroksenoid en olivien tot intermediêre gesteentes, en Mn-ryke rodoniet en piroksmangiet tot Mn-ryke gesteentes. Hierdie variasies gaan gepaard met vergroting van die Mn:Fe verhouding in granaat en ilmeniet-groep minerale met toeneemende afstand van die erts. LA-ICP-MS analises was gebruik om die skaars-aarde element patrone van granaat en apatiet te bepaal. In die erts-liggaam wys hierdie minerale ‘n positiewe Eu anomalie, wat geinterpreteerd word as ‘n hidrotermale kenmerk. In ongemineraliseerde gasheer gesteentes wys granaat en apatiet geen of ‘n negatiewe Eu anomalie. Primêre kenmerke van die Gams Formasie, soos skaars-aarde patrone, the gebande voorkoms van granaat-apatiet erts, die teenwoordigheid van diagenetiese apatiet knolle, en die verspreiding van die redox-sensitiewe elemente Ba en Mn, was gebruik om afleidings oor die paleo-omgewing te maak. Die resultate het gewys dat metapeliet-gesetelde erts afgeset was onder anoksiese bodem water deur presipitasie van Fe en Zn sulfiedes in organiese skalie. Hierdie erts gaan oor in fosforiet-gesetelde erts, granaat-apatiet erts en metaal-ryke gasheer gesteente wat in ‘n suboksiese tot oksiese omgewing ontstaan het. Die grootte van die afsetting, die interne gelaagdheid van die erts, asook die teenwoordigheid van sfaleriet en bariet dui op ‘n distale omgewing relatief tot die hidrotermale bron en presipitasie van die ertsuit digte en gereduseerde hidrotermale vloeistowwe, wat ontstaan het deur die heraktiveering van rustende groeiverskuiwings. Gesaamentlik bewys die geologiese kenmerke van Gamsberg dat gemetamorfiseerde SEDEX en Broken Hill-tipe mineralisasie binne die perke van ‘n enkele afsetting kan voorkom. Die geologiese verhoudings dui aan dat verskille tussen hierdie twee tipes van sedimentgesetelde afsettings meestal veroorsaak word deur omgewings-toestande binne in gelokaliseerde derde orde komme en nie deur fundamentele verskille in ertsvormende prosesse nie.

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Daglioglu, Yasar Mehmet. "A review of sediment-hosted gold deposits of the world with special emphasis on recent discoveries outside the U.S.A." Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005609.

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Most of the Great Basin sediment-hosted gold deposits are located along well defined, northwest-striking trends. Trends coincide with faults, intrusive rocks and magnetic anomalies. Sedimentary host rocks are siltstone, sandstone, conglomerate, argillic, interbedded chert and shales. Silty bedded silty dolomites, limestone and carbonaceous shales are the most favourable hosts. High, and locally, low-angle faults are very important structural features related to the formation of the ore bodies. High-angle faults are conduits of hydrothermal fluids which react, shatter and prepare the favourable host rock. Decalcification, silicification, and argillization are the most common hydrothermal alteration types. Jasperoid (intense silica replacement) is a significant characteristic; not all of these deposits are gold-bearing. Most deposits contain both oxidized and unoxidized ore. Fine grained disseminated pyrite, arsenian pyrite, and carbonaceous material are the most common hosts for gold in many deposits. These deposits are also characterized by high Au/Ag ratios, notable absence of base metal and geochemical associations of Au, As, Sb, Hg, Ba and TI. Recently numerous sediment-hosted gold deposits have been recognized in different regions of the world. They vary in their size, grades, textwe, host rock lithology, degrees of structural control and chemical characteristics. However, they have many common features which are very similar to the general characteristics of sediment-hosted gold deposits in the Great Basin, U.S.A. Besides these similarities, several unusual features are recorded in some newly discovered deposits elsewhere, such as predominant fault controlled paleokarst related mineralization and the lack of two very common trace elements (Hg, TI) in Lobongan/Alason, Indonesia; and Early Proterozoic age metamorphosed host rocks and lack of Sb in Maoling, China. The discovery of the deep ores in the Post-Betze and Rabbit Canyon, Nevada, proposed sediment-hosted Au emplacement at deeper level (4 ± 2 km; Kuehn & Rose, 1995) combined with a lack of field evidence for paleowater table and paleosurface features has ruled out a shallow epithermal origin. Recent discoveries in other parts of the world throw important new light on the ongoing genetic problems. Intrusive rocks are present in nearly all sediment-hosted gold deposits. Numerous intrusion-centred districts worldwide are characterized by tWo or more different mineralization types and consequently by metal zoning. Sediment-hosted gold deposits are proposed as a distal part of intrusion-centred magmatic hydrothermal systems (Sillitoe &Bonham, 1990).

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Fu, Qilin. "An investigation into Plasma Vapor Deposition Aided Chemical Vapor Deposition : A PVD aided CVD process for depositing Nitrogenatoms mixed in Carbon Diamond-Like-Structure is investigated and one such layer is formed with this method." Thesis, KTH, Industriell produktion, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50056.

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The work presented in this master thesis includes experiments and analysis of the Physical Vapor Deposition aided Chemical Vapor deposition. Physical Vapor Deposition is usually deemed as a process of applying plasma phenomenon in highvacuum situation, knocking off the cathode material like particles or atoms, and depositing the knocked off particles onto a substrate surface. Chemical Vapor Deposition process is usually referred to as a process of vaporizing liquid materials into the process chamber and reacting with other substances and forming solid particles. This kind of particles can be deposited onto a substrate surface and forming a coating layer. The by-productsare usually removed with the gas flow in the chamber. In order to assist the chemical reaction process, high temperature on the substrate is usually utilized. It is common knowledge to notice that under high temperature, the crystallographic structure of the substrate might change and result in negative damages. A combined method of using PVD phenomenon to assist the CVD process has been studied in this work and it shows a new trend in the method of coating process. As a result, a layer of nitrogen atoms mixed in Carbon Diamond-Like-Structures has been formedon the substrate surface.

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13

Guo, Li. "Synthesis of one-dimensional boron related nanostructures by chemical vapor deposition." Cincinnati, Ohio : University of Cincinnati, 2008. http://www.ohiolink.edu/etd/view.cgi?ucin1206412343.

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Thesis (Ph.D.)--University of Cincinnati, 2008.
Committee/Advisors: Raj N. Singh PhD (Committee Chair), Relva C. Buchanan PhD (Committee Member), Rodney Roseman PhD (Committee Member), Donglu Shi PhD (Committee Member). Title from electronic thesis title page (viewed Sep.3, 2008). Keywords: Boron nitride nanotube (BNNT); boron nanowire (BNW); chemical vapor deposition (CVD). Includes abstract. Includes bibliographical references.

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14

Li, Ning. "Depositional controls and genesis of the Jinding sandstone-hosted Zn-Pb deposit, Yunnan Province, Southwest China /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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Thesis (Ph. D.)--University of Texas at Austin, 1998.
Vita. One folded ill. in pocket. Includes bibliographical references (leaves 222-235). Available also in a digital version from Dissertation Abstracts.

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15

Zhou, Zhengzhi. "Synthesis of one-dimensional nanostructure materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29703.

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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Deng,Yulin; Committee Member: Hsieh, Jeffery S.; Committee Member: Nair, Sankar; Committee Member: Singh, Preet; Committee Member: Yao, Donggang. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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16

Sechrist, Zachary Aspen. "One-dimensional and three-dimensional photonic crystals created using atomic layer deposition." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239418.

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17

Anderson, Iain Kerr. "Ore depositional processes in the formation of the Navan zinc/lead deposit, Co. Meath, Ireland." Thesis, University of Strathclyde, 1990. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23503.

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18

Ricci, Giovanni. "Organic matter deposition/resuspension in a one-dimensional physical-biogeochemical model. A modelling study." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10595/.

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The shallow water configuration of the gulf of Trieste allows the propagation of the stress due to wind and waves along the whole water column down to the bottom. When the stress overcomes a particular threshold it produces resuspension processes of the benthic detritus. The benthic sediments in the North Adriatic are rich of organic matter, transported here by many rivers. This biological active particulate, when remaining in the water, can be transported in all the Adriatic basin by the basin-wide circulation. In this work is presented a first implementation of a resuspension/deposition submodel in the oceanographic coupled physical-biogeochemical 1-dimensional numerical model POM-BFM. At first has been considered the only climatological wind stress forcing, next has been introduced, on the surface, an annual cycle of wave motion and finally have been imposed some exceptional wave event in different periods of the year. The results show a strong relationship between the efficiency of the resuspension process and the stratification of the water column. During summer the strong stratification can contained a great quantity of suspended matter near to the bottom, while during winter even a low concentration of particulate can reach the surface and remains into the water for several months without settling and influencing the biogeochemical system. Looking at the biologic effects, the organic particulate, injected in the water column, allow a sudden growth of the pelagic bacteria which competes with the phytoplankton for nutrients strongly inhibiting its growth. This happen especially during summer when the suspended benthic detritus concentration is greater.

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Tsikos, Harilaos. "Petrographic and geochemical constraints on the origin and post-depositional history of the Hotazel iron-manganese deposits, Kalahari Manganese Field, South Africa." Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1005599.

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The giant Palaeoproterozoic manganese deposits of the Kalahari manganese field (KMF), Northern Cape Province, South Mrica, have been a world renowned resource of manganese ore for many decades. In recent years, the mineralogical composition, geochemistry and genesis of these deposits have been the objects of many geological investigations, yet their origin remains contentious up to the present day. A characteristic feature of the Kalahari deposits is the intimate association of manganese ore and iron-formation of the Superior-type, in the form of three discrete sedimentary cycles constituting the Hotazel Formation. This striking lithological association is an almost unique feature on a global scale. From that point of view, the present study is effectively the first attempt to shed light on the origin and post-depositional history of the Hotazel succession, using as prime focus the petrographic and geochemical characteristics ofthe host iron-formation. Petrographic and whole-rock geochemical information of iron-formation from the southern parts of the KMF, suggests that the Hotazel iron-formation is almost identical to other iron-formations of the world of similar age and petrological character. The rock exhibits essentially no high-grade metamorphic or low-temperature alteration effects. Mineralogically, it contains abundant chert, magnetite, subordinate amounts of silicate minerals (greenalite, minnesotaite, stilpnomelane) and appreciable concentrations of carbonate constituents in the form of coexisting calcite and ankerite. Such mineralogical composition is indicative of processes occurring in a diagenetic" to burial (up to very low-greenschist facies) metamorphic environment. Bulk-rock geochemical data point towards a simple composition with Si02, total Fe-oxide and CaO being the chief major oxide components. Whole-rock rare-earth element data suggest that the iron-formation precipitated from a water column with chemical signatures comparable to modern, shallow oceanic seawater. The virtual absence of positive Eu anomalies is a feature that compares well with similar data from Neoproterozoic, glaciogenic iron-formations of the Rapitan type, and suggests but only a dilute hydrothermal signal, poten!ially derived from distal submarine volcanic activity. Carbon and oxygen isotope data from iron-formation and Mn-bearing carbonates as well as overlying ferriferous limestone of the Mooidraai Formation, compare well with the literature. The former exhibit variable depletion relative to seawater in terms of both BC and 180, while the latter have signatures comparable to normal marine bicarbonate. Isotopic variations appear to be related to fluctuations in the amount of co-precipitated marine carbonate, in conjunction with processes of coupled organic matter oxidation - FelMn reduction in the diagenetic environment. Oxygen isotope data from quartz-magnetite-calcite triplets suggest that crystallisation took place under open-system conditions, with magnetite being the most susceptible phase in terms of fluid-rock isotopic exchange. Data also suggest that the calcite-magnetite pair may constitute a more reliable geothermometer than the quartz-magnetite one, mainly due to the interlinked diagenetic histories between calcite and magnetite. Iron-formation from the northern parts of the KMF can by categorised into three main classes, namely pristine, altered and oxidised. Pristine iron-formation is identical to the one seen in the southernmost parts of the field. Altered iron-formation corresponds to a carbonate-free derivative of intense oxidation and leaching processes at the expense ofpristine iron-formation, and contains almost exclusively binary quartz-hematite mixtures. The rock appears to have lost essentially its entire pre-existing carbonate-related components (i.e., Ca, Mg, Sr, most Mn and Ba) and displays residual enrichments in elements such as Cr, Th, V, Ni and Pb, which would have behaved as immobile constituents during low-temperature alteration. The low temperature origin of altered iron-formation is supported by oxygen isotope data from quartz-hematite pairs which indicate that isotopically light hematite would have derived from oxidation of magneftte and other ferroussilicate compounds in the presence of a low-temperature meteoric fluid, while quartz would have remained isotopically unchanged. Occasional occurrences of acmite-hematite assemblages suggest localised metasomatic processes related to the action ofNaCI-rich fluids at the expense of altered iron-formation. The conditions of acmite genesis are very poorly constrained due to the very broad stability limits of the mineral in environments ranging from magmatic to surface-related. Oxidised iron-formation constitutes a distinct rock-type and shares common attributes with both the pristine and the altered iron-formation. The rock contains hematite as an important constituent while the amount of magnetite is substantially reduced. With regard to carbonate nlinerals, calcite contents are clearly very low or absent, having being replaced in most instances by a single, Mgenriched, dolomite/ankerite:type species. Oxidised iron-formation contains somewhat higher amounts of iron and reduced amounts of Sr and Ba relative to pristine iron-formation, whereas enrichments in elements such as Ni, Th, Pb, Cr, and V are seen, similar to altered iron-formation. Oxidised iron-formation appears to have originated from processes of dissolution-mobilisationreprecipitation of solutes derived primarily from leaching that produced altered iron-formation. It is proposed that the Hotazel iron-formation and associated manganese deposits were formed as a result of episodic sea-level fluctuations in a stratified depositional environment that gradually evolved into a shallow carbonate platform. A critical parameter in the development of manganese sediment may include regional climatic patterns related to a glacial event (Makganyene diamictite) prior to deposition of the Hotazel strata. This suggestion draws parallels with processes that are believed to have led to the formation of worldwide iron-formations and associated manganese deposits subsequent to Neoproterozoic episodes of glaciation. Submarine volcanism related to the underlying Ongeluk lavas appears to have had very little (if any) metallogenic significance, while evidence for a sudden rise in the oxygen contents of the atmosphere and ambient waters is lacking. With regard to later alteration processes, combination of geological and geochemical data point towards the potential influence of surface weathering prior to deposition of rocks of the unconformably overlying Olifantshoek Supergroup, possibly coupled with fault- and/or thrustcontrolled fluid-flow and leaching of the Hotazel succession during post-Olifantshoek times.

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Yu, Kyle Kai-Hung. "Interfacial Electrochemistry of Copper and Spectro-Electrochemical Characterization of Oxygen Reduction Reaction." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103416/.

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The first part of this dissertation highlights the contents of the electrochemical characterization of Cu and its electroplating on Ru-based substrates. The growth of Ru native oxide does diminish the efficiency of Cu plating on Ru surface. However, the electrochemical formed irreversible Ru hydrate dioxide (RuOxHy) shows better coverage of Cu UPD. The conductive Ru oxides are directly plateable liner materials as potential diffusion barriers for the IC fabrication. The part II of this dissertation demonstrates the development of a new rapid corrosion screening methodology for effective characterization Cu bimetallic corrosion in CMP and post-CMP environments. The corrosion inhibitors and antioxidants were studied in this dissertation. In part III, a new SEC methodology was developed to study the ORR catalysts. This novel SEC cell can offer cheap, rapid optical screening results, which helps the efficient development of a better ORR catalyst. Also, the SEC method is capable for identifying the poisoning of electrocatalysts. Our data show that the RuOxHy processes several outstanding properties of ORR such as high tolerance of sulfation, high kinetic current limitation and low percentage of hydrogen peroxide.

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Cheng, An-jen Park Minseo Tzeng Y. "One dimensional zinc oxide nanostructures for optoelectronics applications solar cells and photodiodes /." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Electrical_and_Computer_Engineering/Dissertation/Cheng_An-jen_33.pdf.

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22

Duff, Shamus. "Ore Types of the Auriferous Lalor VMS Deposit, Snow Lake, Manitoba: Implications for Genesis and Post Depositional Processes." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34586.

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The Lalor deposit is a newly discovered Paleoproterozoic volcanogenic massive sulphide (VMS) deposit located at the east end of the Flin Flon-Snow Lake belt within the Snow Lake arc assemblage. Lalor is the largest of 11 VMS deposits in the Snow Lake arc assemblage, with combined resources and reserves of 25.3 Mt and average grades of 2.9 g/t Au, 25 g/t Ag, 5 wt% Zn and 0.79 wt% Cu, including 8.8 Mt at 4.6 g/t Au. Lalor and all other deposits in the Snow Lake arc assemblage have been affected by intense polyphase deformation and amphibolite facies metamorphism. As a result, both the original hydrothermal alteration assemblages and the ore mineral assemblages have been completely recrystallized. However, a variety of different ore types have been preserved, allowing the partial reconstruction of the hydrothermal system, including massive Fe-Zn sulphide lenses, discordant Cu-Au stringer zones, and distinctive precious metal-rich Au-Ag-Pb-Cu zones. The different ore types occur in a series of stratigraphically and structurally “stacked” ore lenses that partly overlap but still largely preserve the original architecture of the deposit. The ore is distributed in 12 discrete lenses or zones of mineralization that are interpreted to be the result of several distinct and overlapping hydrothermal events. Type 1 Fe-Zn massive sulphide ore is the most common ore type in six ore lenses and consists of massive coarse-grained pyrite and sphalerite with trace galena in dominantly quartz-muscovite±kyanite-biotite schist (K alteration association). Type 2 Cu-Au mineralization consists of semi-massive and stockwork chalcopyrite and pyrrhotite in garnetiferous quartz-biotite±staurolite-amphibole-cordierite gneisses (footwall Mg-Fe alteration association). Despite extensive recrystallization and local remobilization, these two ore types are interpreted to represent the (metamorphosed) low- and high-temperature ore assemblages, respectively, of a typical volcanogenic massive sulphide deposit. Type 3 Au-Ag-Pb-Cu-rich ore consists of stringer and disseminated sulphides and sulphosalts mainly hosted in chlorite-carbonate-actinolite schist (Mg-Ca and Ca alteration associations). Galena is an important indicator of Au mineralization and occurs in this ore type as fine-grained blebs in a matrix of chlorite, dolomite, calcite, anthophyllite, Ca-plagioclase, and calc-silicates (epidote, grossular, diopside, Ca-amphibole ± scapolite). Where abundant, the galena is associated with chalcopyrite, pyrite, pyrrhotite and minor to trace sphalerite, Ag-Sb-Pb sulphosalts, electrum and native gold. Type 4 low-sulphide ore contains ≤10 vol% disseminated pyrite in quartz-biotite-anthophyllite gneiss, with minor chlorite, staurolite, and coarse almandine garnet, and has variable Au grades. The sulphides and sulphosalts in ore types 3 and 4 are interpreted to be metamorphically remobilized from pre-existing disseminated mineralization. The hydrothermal system developed during two main episodes of seafloor volcanism. Type 1 massive sulphides in the 10 and 11 lenses and in the 20, 30, 31, and 40 lenses were formed at the paleoseafloor. These lenses are underlain by Type 2 Cu-Au stockwork mineralization (27 Lens) and originally conformable zones of Type 3 Au-Ag-Pb mineralization (21, 24, 25, 26, and 28 lenses). The large Cu-Au stockwork zone (27 Lens) may have been the main feeder of the deposit and is partly continuous with disseminated Au-Ag-Pb-Cu galena-sulphosalts mineralization below the 20 base metal Lens. The Au-Ag-Pb-Cu mineralization is thought to have formed in the subseafloor from late-stage, lower-temperature hydrothermal fluids (ca. <300°C). In this model, significant Au was introduced first by high-temperature (>300°C) fluids responsible for the Type 2 Cu-Au mineralization and then by lower-temperature (possibly boiling) hydrothermal fluids responsible for Type 3 Ag-Au-Pb-Cu mineralization. Although all the ore types are extensively recrystallized and partly remobilized, their distribution strongly supports primary hydrothermal Au enrichment at Lalor. The lead isotopic compositions of the ore galena show no evidence of post-magmatic disturbance that would be expected if Au had been introduced during deformation and metamorphism (e.g., as in the nearby New Britannia orogenic Au deposit), and the Au-rich assemblages are very similar to those that commonly occur in unmetamorphosed Au-rich volcanogenic massive sulphide deposits.

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23

Barzegar, HamidReza. "Synthesis and Characterization of Carbon Based One-Dimensional Structures : Tuning Physical and Chemical Properties." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-97551.

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Carbon nanostructures have been extensively used in different applications; ranging from electronic and optoelectronic devices to energy conversion. The interest stems from the fact that covalently bonded carbon atoms can form a wide variety of structures with zero-, one- and two-dimensional configuration with different physical properties. For instance, while fullerene molecules (zero-dimensional carbon structures) realize semiconductor behavior, two-dimensional graphene shows metallic behavior with exceptional electron mobility. Moreover the possibility to even further tune these fascinating properties by means of doping, chemical modification and combining carbon based sub-classes into new hybrid structures make the carbon nanostructure even more interesting for practical application. This thesis focuses on synthesizing SWCNT and different C60 one-dimensional structures as well as tuning their properties by means of different chemical and structural modification. The purpose of the study is to have better understanding of the synthesis and modification techniques, which opens for better control over the properties of the product for desired applications. In this thesis carbon nanotubes (CNTs) are grown by chemical vapor deposition (CVD) on iron/cobalt catalyst particles. The effect of catalyst particle size on the diameter of the grown CNTs is systematically studied and in the case of SWCNTs it is shown that the chirality distribution of the grown SWCNTs can be tuned by altering the catalyst particle composition. In further experiments, incorporation of the nitrogen atoms in SWCNTs structures is examined. A correlation between experimental characterization techniques and theoretical calculation enable for precise analysis of different types of nitrogen configuration in SWCNTs structure and in particular their effect on growth termination and electronic properties of SWCNTs are studied. C60 one-dimensional structures are grown through a solution based method known as Liquid-liquid interfacial precipitation (LLIP). By controlling the crystal seed formation at the early stage of the growth the morphology and size of the grown C60 one-dimensional structures where tuned from nanorods to large diameter rods and tubes. We further introduce a facile solution-based method to photo-polymerize the as-grown C60 nanorods, and show that such a method crates a polymeric C60 shell around the nanorods. The polymeric C60 shell exhibits high stability against common hydrophobic C60 solvents, which makes the photo-polymerized nanorods ideal for further solution-based processing. This is practically shown by decoration of both as grown and photo-polymerized nanorods by palladium nanoparticles and comparison between their electrochemical activities. The electrical properties of the C60 nanorods are also examined by utilizing a field effect transistor geometry comprising different C60 nanorods. In the last part of the study a variant of CNT is synthesized in which large diameter, few-walled CNTs spontaneously transform to a collapsed ribbon shape structure, the so called collapsed carbon nanotube (CCNT). By inserting C60 molecules into the duct edges of CCNT a new hybrid structure comprising C60 molecules and CCNT is synthesized and characterized. A further C60 insertion lead to reinflation of CCNTs, which eventually form few-walled CNT completely filled with C60 molecules.

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24

Stone, Michelle Susanne. "Depositional history and mineralisation of tertiary channel iron deposits at Yandi, Eastern Pilbara, Australia." University of Western Australia. School of Earth and Geographical Sciences, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0082.

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[Truncated abstract] Detailed sedimentological, petrographical, geochemical and palynological studies have provided insight into the source rocks and the processes that operated during formation of the Tertiary Yandi channel iron deposit (CID) of the eastern Pilbara, Western Australia. Yandi is the largest and most valuable CID in the world, accounting for more than 2.5% of global iron production in 2003, and is the type-example of CID. The Yandi CID occupies the palaeo-Marillana Creek in the central Hamersley Ranges. It is near-coincident-with the modern Marillana Creek which incised Proterozoic bedrock of the Weeli Wolli Formation (Hamersley Group) and associated dolerite intrusions. Three lithostratigraphic units fill the palaeo-Marillana Creek and comprise the Marillana Formation. The units in stratigraphic order are the: (1) Munjina Member; (2) Barimunya Member, which hosts the majority of the iron resource; and (3) Iowa Eastern Member. Fossil pollen and spores in organic-rich claystones in the Munjina Member indicate that deposition of the Marillana Formation most likely commenced in the Early Oligocene in response to erratic seasonal flows with high energy flood events and intervening quiescent suspension settling of clays. The Marillana Formation consists of twelve facies. These conglomerate and clay facies form three facies associations. The basal facies association is composed of polymictic conglomerate, clay and interbedded CID that represents a lag deposit along the base of the palaeochannel. This facies association characterises the Munjina Member. The second facies association consists of iron-rich conglomerate sheets, bars and subordinate scour-fills and characterises the Barimunya Member. Channel iron deposits of the overlying Iowa Eastern member consist of reworked Barimunya Member iron conglomerates. The upper facies association is polymictic conglomerate with clay that characterises the remainder of the Iowa Eastern Member. Polymictic iron conglomerate in the Munjina and Barimunya Members contains Weeli Wolli Formation and dolerite clasts indicating local derivation. Rare earth element profiles of the other iron conglomerate facies indicate derivation of the Barimunya and Iowa Eastern CID from a different source. These iron conglomerates are characterised by relatively flat LREE profiles. The LREE exhibit an enriched profile approaching the MREE [(average La/Nd)N = 0.7], and the HREE profile shows minor enrichment approaching ytterbium [(average Dy/Yb)N = 0.9]. Comparison of iron conglomerate REE profiles to those of the bedrock indicates that these conglomerates were most probably derived from the Joffre Formation BIF of the Hamersley Group

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Grimm, Daniel. "A combined experimental and theoretical approach towards the understanding of transport in one-dimensional molecular nanostructures." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1218037048209-51309.

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This thesis comprises detailed experimental and theoretical investigations of the transport properties of one-dimensional nanostructures. Most of the work is dedicated to the exploration of the fascinating effects occurring in single wall carbon nanotubes (SWCNT). These particular nanostructures gained an overwhelming interest in the past two decades due to its outstanding electronic and mechanical features. We have investigated the properties of a novel family of carbon nanostructures, named here as Y-shaped rings. The studies show that they present very interesting quantum interference effects. A high structural stability under tensile strain and elevated temperatures is observed. Within the semi-classical potential adopted, the critical strain values of structure rupture lie in the same range of their pristine SWCNT counterparts. This is directly verified by the first observations of these ring-like structures in a transmission electron microscopy. A merging process of asymmetric into symmetric rings is investigated in-situ under electron beam irradiation at high temperatures. The electronic properties of these systems are theoretically studied using Monte Carlo simulations and environment dependent tight-binding calculations. From our results, we address the possibility of double-slit like interference processes of counter-propagating electron waves in the ring-like structures. The nature of well defined, sharp peaks in the density of states are determined as the discrete eigenenergies of the central loop part. Furthermore, the formation and dispersion of standing waves inside the ring is shown to originate from the quantum-dot like confinement of each branch between the leads. The obtained dispersion relation is shown to be the same occurring in purely one-dimensional quantum dots of similar geometries. Furthermore, Fabry-Perot-like interferences are observed. We established at the IFW a bottom-up processing route to fabricate nanotube based electronic devices. The SWCNTs are grown by chemical vapor deposition and we present a detailed study of the different approaches to obtain individual nanotubes suitable for a successful integration into electronic devices. Wet-chemistry and ultra-thin films as well as ferritin were employed as catalyst particles in the growth of SWCNT samples. By adjusting the optimized process parameters, we can control the obtained yield from thick nanotube forests down to just a couple of free-standing individual SWCNTs. The nanotubes are localized, contacted by standard e-beam lithography and characterized at ambient- as well as liquid helium temperatures. We usually obtain quite transparent contacts and the devices exhibit metallic or a mixed metallic/semiconducting behavior. The well-known memory effect upon gate voltage sweeping as well as single electron tunneling in the Coulomb blockade regime are addressed.

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Gao, Puxian. "Piezoelectric Nanostructures of Zinc Oxide: Synthesis, Characterization and Devices." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7564.

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In this thesis, a systematic study has been carried out on the synthesis, characterization and device fabrication of piezoelectric ZnO nanstructures. The achieved results are composed of the following four parts. Firstly, through a systematic investigation on the Sn-catalyzed ZnO nanostructure, an improved understanding of the chemical and physical process occurring during the growth of hierarchical nanostructures has been achieved. Decomposed Sn from SnO2 has been successfully demonstrated and proved to be an effective catalyst guiding the growth of not only aligned ZnO nanowires, but also the hierarchical nanowire-nanoribbon junction arrays and nanopropeller arrays. During the vapor-liquid-solid (VLS) catalyzing growth process at high temperature, Sn in the liquid state has been proved to be able to guide the growth of nanowires and nanoribbons in terms of growth directions, side facets, and crystallographic interfaces between Sn and ZnO nanostructures. Secondly, using pure ZnO as the only source material, by precisely tuning and controlling the growth kinetics, a variety of hierarchical polar surface dominated nanostructures have been achieved, such as single crystal nanorings, nanobows, nanosprings and superlattice nanohelices. High yield synthesis of ZnO nanosprings over 50% has been successfully obtained by mainly controlling the pre-pumping level associated with the partial pressure of residual oxygen during the vapor-solid growth process. The rigid superlattice nanohelices of ZnO have been discovered, which is a result of minimization of the electrostatic energy induced by polar surfaces. The formation process of the nanohelix has been systematically characterized. Thirdly, two new strategies have been successfully developed for fabricating ZnO quantum dots and synthesis of ZnO nanodiskettes and nanotubes. The formation process is based on a common concept of self-assembly. Finally, a series of devices and applications studies based on several piezoelectric ZnO nanostructures, such as nanobelts, nanopropellers and nanohelices, have been carried out utilizing the electro-mechanical resonance, bio-surface functionalization, devices fabrication and electrical characterization. Individual nanobelt and nanohelix based nanodevices have been successfully fabricated for applications in chemical and biological sensing. The study opens a few new areas in oxide nanostructures and applications.

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Bergh, Eugene W. "A one-year, postfire record of element deposition and cycling in the Kogelberg sandstone fynbos mountain ecosystem of the Western Cape, South Africa by Eugene W. Bergh." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/10101.

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Includes abstract.
Includes bibliographical references.
Fire is a critical component of the fynbos ecosystem and this study documents the macronutrient (C1, Na, So4, Mg, Ca and K) dynamics of the fynbos for one year following a major fire event on 3 June 2010. Chloride and sodium in rainwater and stream water were found to be primarily derived from a marine aerosol source.

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28

Gaona, Narvaez Tatiana. "Lower Aptian Comparative Stratigraphy of the Basco-Cantabrian Region (Spain) and Eastern Cordillera (Colombia): implications for local factors in the depositional record of Oceanic Anoxic Event 1a (OAE-1a)." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/952.

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An important episode of carbon sequestration, Oceanic Anoxic Event 1a (OAE-1a), characterizes the Lower Aptian worldwide, and is mostly known from deeper-water settings. The present work of two Lower Aptian deposits, Madotz (N Spain) and Curití Quarry (Colombia), is a multiproxy study that includes fossil assemblages, microfacies, X-ray diffraction bulk and clay mineralogy, elemental analyses (major, minor, trace elements), Rock-Eval pyrolysis, biomarkers, inorganic and organic carbon content, and stable carbon isotopes. The results provide baseline evidence of the local and global controlling environmental factors influencing OAE-1a in shallow-water settings. The data also improve our general understanding of the conditions under which organic-carbon-rich deposits accumulate. The sequence at Madotz includes four intervals (Unit 1; Subunits 2a, 2b and 2c) that overlap the times prior to, during and after the occurrence of OAE-1a. The Lower Unit 1(3m thick) is essentially siliciclastic, and Subunit 2a (20m) contains Urgonian carbonate facies that document abruptly changing platform conditions prior to OAE-1a. Subunit 2b (24.4 m) is a mixed carbonate-siliciclastic facies with orbitolinid-rich levels that coincides with OAE-1a δ13C stages C4-C6, and is coeval with the upper part of the Deshayesites forbesi ammonite zone. Levels with pyrite and the highest TOC values (0.4-0.97%), interpreted as accumulating under suboxic conditions, and are restricted to δ13C stages C4 and C5. The best development of the suboxic facies is at the level representing the peak of the transgression. Subunit 2c, within δ13C stage C7, shows a return of the Urgonian facies. The 23.35-m section at Curití includes a 6.3-m interval at the base of the Paja Formation dominated by organic-rich marlstones and shales lacking benthic fossils and bioturbation, with TOC values as high as 8.84%. The interval overlies a level containing reworked and phosphatized assemblages of middle Barremian to lowest Aptian ammonites. The range of values and the overall pattern of the δ13Corg (-22.05‰ to -20.47‰) in the 6.3m-interval is comparable with Lower Aptian δ13C stage C7. Thus, conditions of oxygen depletion at this site also occurred after Oceanic Anoxic Event-1a, which developed between carbon isotope stages C3 and C6. Both sites, Madotz and Curití, attest to the importance of terrigenous and nutrient fluxes in increasing OM productivity that led to episodic oxygen deficiency.

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29

Huber, Rupert Verfasser], Dirk [Akademischer Betreuer] Grundler, and Paolo [Akademischer Betreuer] [Lugli. "Control of Spin Waves on the Nanoscale in One-Dimensional Magnonic Crystals and Atomic Layer Deposition of Metallic Ferromagnets for Second Generation of Nanomaterials / Rupert Huber. Gutachter: Dirk Grundler ; Paolo Lugli. Betreuer: Dirk Grundler." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1047185474/34.

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30

Gestraud, Cecilia. "Synthèse, fonctionnalisation et assemblage de nanodisques d'argent." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0112.

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Les nanoparticules d'argent, déjà largement utilisées en catalyse, optique et électronique, trouvent aujourd'hui de nouvelles applications comme l'imagerie, la photonique ou la détection chimique et biochimique. Parmi ces applications, certaines requièrent des morphologies particulières comme des bâtonnets ou des disques (films conducteurs, spectroscopie Raman exaltée) quand d'autres impliquent principalement une surface spécifique importante comme par exemple en catalyse hétérogène. Les nanoparticules métalliques anisotropes sont classiquement réalisées en deux étapes, séparant la formation des germes et la croissance de ceux-ci, afin de mieux en contrôler la morphologie mais la séparation en deux étapes rend le transfert à l'échelle industrielle délicat à cause des longues périodes d'incubation et de lavage nécessaires. Nous avons choisi de nous intéresser à la synthèse dirigée de nanoparticules anisotropes, en particulier des nanodisques d'argent, ainsi que leur assemblage, en solution et sur des surfaces. Dans nos travaux, nous avons retenu une approche permettant de réaliser les deux étapes de la formation de nanodisques d'argent dans un même milieu réactionnel. Le principe repose sur l'utilisation de deux réducteurs, l'un faible et l'autre fort, dont les cinétiques de réduction très différentes permettent le contrôle de l'anisotropie. Cette méthode est simple et permet de réduire le temps de synthèse mais nécessite un bon contrôle des différents paramètres expérimentaux. Le temps entre l'ajout des deux réducteurs détermine notamment la morphologie des objets formés. Il existe en réalité une gamme optimale pour ce temps qui dépend particulièrement de la température de la synthèse. Afin de faire varier les propriétés optiques de ces nanodisques, différentes stratégies peuvent être envisagées. Notre choix s'est tourné vers la formation d'assemblages, en solution dans un premier temps, puis sur des surfaces par des méthodes de dépôt. L'adsorption de molécules organiques bifonctionnelles peut permettre de réaliser des assemblages en solution : une des fonctions a une affinité avec l'argent et l'autre interagit avec les fonctions libres des autres nanoparticules grâce à des liaisons hydrogène ou électrostatiques par exemple. Les assemblages peuvent également être réalisés sur des surfaces. Nous nous sommes tournés vers des méthodes de dépôts originales, qui permettent des assemblages dirigés des nanodisques par voie électrostatique. Nous avons démontré que ces assemblages sont de bons candidats pour développer des substrats SERS micro-structurés
Silver nanoparticles, used extensively in catalysis, optics and electronics, are now emerging in new applications such as imaging, photonics or chemical and biochemical detection. Among these applications, some require particular morphologies such as rods or disks (conductive films, enhanced Raman spectroscopy) while others mainly involve a large specific surface area such as in heterogeneous catalysis. Anisotropic metal nanoparticles are traditionally produced in two stages, separating the formation of seeds and their growth, in order to better control their morphology. However, the two-stage synthesis makes the transfer on industrial scale difficult because of the long incubation time and the washing steps required. In this context, we decided to focus on the synthesis of anisotropic nanoparticles, in particular silver nanodisks, as well as their assembly in solution and on surfaces. In our work, we adopted an approach that allows to carry out the two stages of the formation of silver nanodisks in the same reaction medium. The principle is based on the use of two reducers, one weak and one strong, with different kinetic reduction rates, allowing the control of anisotropy. This method is simple and fast but requires good control of the experimental parameters. The time between the addition of the two reducers determines the morphology of the formed objects. There is actually an optimal range for this time, which depends particularly on the temperature of the synthesis. In order to vary the optical properties of these nanodisks, different strategies can be considered. We chose to form assemblies both in solution and on surfaces by different deposition techniques. The adsorption of bifunctional organic molecules can provoke the formation of assemblies in solution: one function has an affinity with silver and the other interacts with the free functions of the other nanoparticles through hydrogen or electrostatic bonds for example. Assemblies can also be made on surfaces. We have been working on original deposition method, which allow an oriented assembly of nanodisks through electrostatic forces.We have demonstrated that these assemblies are good candidates for developing micro-structured SERS substrates

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31

Wurst, A. T. "Analyses of late stage, Mesoproterozoic, syn and post tectonic, magmatic events in the Moonta Sub-domain: Implications for Cu-Au mineralisation in the "Copper Triangle" of South Australia." Thesis, 1994. http://hdl.handle.net/2440/88299.

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This item is only available electronically.
The Moonta-Wallaroo area has been of economic, historical and scientific importance in South Australia's history for over 130 years. The nature of mineralisation in the area has long been a point of conjecture. This study looks at the nature of ore deposition and specifically its relationship to granitoids and pegmatites in the Moonta Subdomain. Using various analytical techniques the study has shown that granitoids in the region have distinctly different petrological, textural, structural, geochemical and isotopic characteristics. Two main granitoids were·recognised as the Tickera Granite and the Arthurton Granite. Geochemical studies suggest that magmatism in the Moonta Subdomain was a continuous process in the Mesoproterozoic. The older Tickera Granite, displays syn-collisional, more I-type characteristics and syn-collisional S-type characteristics (represented by a monzonite and a tonalite respectively). The younger Arthurton Granite shows A-type, anorogenic characteristics. A temporal shift from syn-collisional to anorogenic granites suggests a tectonic control on magma generation and emplacement during this period. Trace element characteristics of the Arthurton Granite are homogeneous over a wide spatial range, is suggesting that it may be part of an extensive batholith. Geochemistry of pegmatites implies that they were late stage fractionation products, related to these granite intrusions. A study of the Tickera Granite (Point Riley-Nth Beach) revealed a dominant structural fabric which suggested the granite was intruded into a tectonic regime in which shearing was prominent. Sediments intruded by the granite suggested deposition in a shallow intracratonic rift setting, followed by polyphase deformation during orogenic activity and subsequent shearing possibly related to the enigmatic Wartakan Event. Isotopic studies highlighted differences in the petrogenetic source regions of the Tickera Granite and the Arthurton Granite. The Tickera Granite (represented by monzonite) displayed more mantle like characteristics while the Arthurton Granite (represented by granite from Arthurton and adamellite from Moonta) displayed more crustal features, highlighting its A-type nature. Studies also showed that a pegmatite from the Wheal Hughes was most like the later of these two granites. Tourmaline studies of Wheal Hughes samples implicated derivation from a metapelite and calcsilicate precursor, a common feature of most tourmaline studied in the area. This may indicate remobilisation of boron rich fluids and metals from these sediments The close association of tourmaline with the ore in the Moonta Mines region implied a common source region. A tectonic setting and model for ore deposition is proposed on the basis of the study findings. The model proposed the remobilisation of metals which were initially deposited in a ensialic rift type environment (common to other Palaeoproterozoic metalliferous terrains) by the intrusion of the Tickera Granite, during regional shearing. And further concentration of metals by subsequent intrusions of the Arthurton Granite batholith.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1994

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32

Gutierrez, Gay Nell 1955. "Controls on ore deposition in the Lamotte Sandstone, Goose Creek mine, Indian Creek subdistrict, southeast Missouri." 1987. http://hdl.handle.net/2152/20448.

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The Indian Creek subdistrict is the northernmost mineralized area in the Southeast Missouri district and is unique because ore-grade concentrations of sulfides occur within the Lamotte Sandstone. The Lamotte Sandstone-hosted Goose Creek mine is located on the northern end and the Bonneterre Dolomite-hosted Indian Creek mine on the northwestern side of a N30°E-trending, Precambrian rhyolite ridge. A saddle on the northern end of the ridge separates the Indian Creek subdistrict from another probable high along the same trend to the north. Lamotte deposition was influenced by pre-Lamotte basement topography, and local thickness ranges from 0 where it pinches out against the ridge to over 100 ft toward the basin. It is comprised of a thin, discontinuous basal cobble conglomerate overlain by a medium-grained, moderately to poorly sorted, well-rounded quanzarenite. Fourteen authigenic minerals, plus hydrocarbons cement the Lamotte Sandstone at Goose Creek in the following paragenetic sequence: dolomite - framboidal pyrite - marcasite - cuboctahedral pyrite - bravoite - bladed marcasite - pyrite - quartz dissolution - brecciation - siegenite - marcasite - dolomite - brecciation - chalcopyrite - quartz dissolution - sphalerite - galena (cuboctahedral) - quartz - galena (cubic) - dolomite - gypsum - hydrocarbon - kaolinite - illite - calcite - hydrocarbon. Primary and secondary porosity in the Lamotte vary between 1 and 20 volume percent and authigenic cements account for up to 35 volume percent of the sandstone. Quartz overgrowths are the most common cement in the Lamotte Sandstone at Goose Creek, comprising from 1 to 11 volume percent of the rock. Galena is the most abundant sulfide and commonly occurs in 1 to 3 mm blebs, averaging 3-4 volume percent. Chalcopyrite averages 0.5 volume percent, but high grade concentrations reach 8-10 volume percent locally. Sulfides in the Lamotte Sandstone in the Indian Creek subdistrict commonly occur within 40 ft of the Bonneterre-Lamotte contact, with the highest concentrations within 20 ft or less of the contact. Structure maps of the lead- and copper- bearing-zones mimic the basement topography, suggesting that the Precambrian basement was the major controlling factor on ore deposition in the Indian Creek subdistrict. Vertical tubes of sulfides, which cross-cut bedding near the Lamotte pinchout in the Goose Creek mine, suggest that the ore-bearing fluids moved through the sandstone aquifer until the pinchout forced them into the overlying Bonneterre. There the fluids were channeled through the grainstone-algal reef complex along the N30°E-trending Precambrian ridge. Limited fluid inclusion data for Bonneterre-hosted sphalerite indicate that the mineralizing fluid was a Na-Ca-Cl brine with temperatures between 105 and 120° C.
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33

Dobosz, Agatha. "Characterization of Carlin-Type Auriferous Arsenian Pyrite from the Goldstrike Property using EMP, SIMS, and VESPERS Synchrotron u-XRF: Constraints to Ore Deposition Mechanisms." Thesis, 2012. http://hdl.handle.net/1974/7447.

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The Goldstrike property, located in northern Nevada within the Carlin Trend, contains one of the largest Carlin-type Au deposits in the world. The vast majority of this mineralization, formed in the Eocene, is in the form of Au-bearing, trace element-rich arsenian pyrite, either as very fine grains, overgrowths on earlier pyrite, or as reported in this study, patchy zones with high As values. Eight samples characteristic of Ore I and Ore II - ore types defined by Almeida et al. (2010) - were selected and analysed using electron microprobe, secondary ion mass spectrometry, and synchrotron !-XRF. !-XRF is a non-destructive technique for the elemental analysis of these samples with additional structural analysis capability. Although Ore I and Ore II yield similar Au values in whole rock analyses, and in the samples selected in this study, Ore II yielded much lower Au and trace element values in pyrite than Ore I. However, free gold was found in an Ore II sample, which explained their similar gold grade in whole rock. Two compositional trends were identified based on the ratio of Au and As in auriferous pyrite from both Ore I and Ore II: 1) those above an Au/As ratio of 0.007, characterized by elevated Ag, Au, As, Cu, Hg, Sb, and Tl that trend positively with respect to Au. The maximum value of Au ranges from 0.12 to 0.15at% (0.56 to 0.68wt%), occurring at an As concentration of 2.5 to 4.3at% (5 to 7.4wt%), and 2) those below an Au/As ratio of 0.007, characterized by As above the optimal range associated with lower Au and lower trace element concentrations. The peak in As corresponds well with the theoretical maximum amount of As that can be incorporated as a solid solution in pyrite (~6wt%) before the structure changes to a two-phase pyrite-arsenopyrite system. The less structurally stable solid solution has a more reactive surface that is more amenable to adsorption of other trace elements, including Au, especially with increased As.
Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-08-27 14:03:12.542

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34

Syu, Jia-Wei, and 許家瑋. "Growing one-dimensional Indium Oxide Nanowires by Chemical Vapor Deposition." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/5a2shq.

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碩士
國立東華大學
材料科學與工程學系
95
In recent years, nanostructures have attracted much attention because of the potential for electronic and optoelectronic applications. Nanostructured semiconductors such as III-V and oxides have been studied and developed. Nanostructured indium oxide ( nanowire, nanobelt, nanoparticles et al.), a wide band-gap ( 3.55 eV – 3.76 eV ) transparent semiconducting material, has been widely used in the microelectronic applications including solar cells, flat panel display materials, and gas sensors. Several one-dimensional In2O3 nanowires and nanorods have been fabricated by using different methods such as laser ablation, electrodeposition and oxidizing method, one-step annealing method, physical vapor deposition, and chemical vapor deposition etc. However, the growth of one-dimensional In2O3 by the CVD method with indium metal or In2O3 powder as the indium sources was carried out at higher temperatures above 800oC. In general, they use indium metal or In2O3 powder as original source. Here we reported a method of growing In2O3 nanowires at lower temperatures of 600 – 700 oC with a novel indium source combining indium shot and InCl3 powder. The process parameters such as the indium source, the temperature of indium source, the growth temperature, the growth duration, the oxygen flow rate, and the substrate were investigated to study the growth of one-dimensional In2O3 nanowires. 1-D In2O3 nanowires with a diameter of 10 – 40 nm and a length of several tens to several hundreds micrometers were obtained with a combined indium source at temperature of 450oC, under growth temperatures of 600 – 700oC, and with a oxygen flow rate of 20 sccm. The produced InCl vapor from the combined indium source was responsible for the growth of 1-D In2O3 nanowires. In-Au alloy catalysts at the tip of In2O3 nanowires were observed by TEM, which identified a growth mechanism of vapor-liquid-solid (VLS). The structure of In2O3 nanowires was cubic with the aid of TEM analysis. The growth of our 1-D In2O3 nanowires involved the steps of the formation of InCl vapor, the coverage of adsorbed InCl and oxygen on Au catalyst, the dissociation of InCl and dissolution of indium into the gold catalyst, and the over-saturation of indium in Au.

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35

Huang, Sung-Chien, and 黃松建. "Growth of one dimensional GaN nanostructure by using chemical vapor deposition." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/vb63vv.

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碩士
國立臺灣科技大學
化學工程系
95
Gallium nitride(GaN) nanostructure were grown by metalorganic chemical vapor deposition using trimethylgallium(TMGa) as source material for Ga, and Ge nanowire、ZnO nanorod、Si(111) with 1 nm of Au as substrates. Si(111) coated with 1 nm Au was acted as a substrate. Heating the substrate until its temperature was 800℃ would form a sheet-like nanostructures. In the other hand, heating the substrates until its temperature was 550℃ would form a rod-like nanostructures. Well-aligned GaN nanorod structure were formed by increasing the feed ratio of Ⅴ/Ⅲ to 15000. GaN nanodots were formed on Ge nanowire substrate. Core-shell structure of GaN/ZnO nanorod、GaN/Ge nanowire were formed by atomic layer epitaxy(ALE) technique. The selective growth process of GaN nanorod on ZnO nanorod, which was coated with SiO2 and acted as substrate, was failed due to high temperature(850℃) and high NH3 concentration.

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36

Ya-HwangCheng and 鄭亞寰. "Fabrication of one dimensional insulated micropattern of silica by electrophoretic deposition." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/26960780855311366373.

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碩士
國立成功大學
材料科學及工程學系碩博士班
98
Micropattern of silica was fabricated on interdigitated array (IDA) electrode, which is an ideal structure of MLCC (multilayer ceramic capacitor) by EPD (electrophoretic deposition). This technique was applied to fabricate insulated layer of inner electrode of MLCC to increase the effective capacity area. First, silica powder was dispersed with different methods in isopropanol (IPA) and then suspension properties were analyzed. From this analysis, it is found that isoelectic point (IEP) of silica was close to 5, zeta potential of silica reached maximum value of -38 mV at pH=10.5, and the average particle size was estimated to be 58 nm. Then, silica particles were deposited on IDA electrodes using ether two electrodes or three electrodes system by EPD. The three electrodes system produced better deposition selectivity, which may due to electric field distribution. Smaller IDA electrode performed faster deposition rate and need lower voltage to fabricate micropattern. Crack-free micropattern of silica was fabricated under applied voltage of 10 V for 20 s followed sintering at 800?C. The resistance of micropattern was found to be 7.04×109 ohm measured by electric property analyzer, and the adhesion of micropattern was better after sintering. Base on results, EPD process using three electrodes system was very fast, with high selective and was suitable for fabrication of insulated layer for MLCC.

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37

Kuo, Chih-Yun, and 郭芷昀. "Atomic layer deposition of Pt catalysts on one dimensional InN nanostructures." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/26636397062512083982.

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碩士
國立臺灣科技大學
化學工程系
96
One-dimensional InN nanostructures with large surface area and high conductivity were used as templates for the deposition Pt catalyst by using atomic layer deposition (ALD) method. The chemical composition, morphology and electrochemical characteristics which were applicable for the anode electrode for direct methanol fuel cell (DMFC) were also investigated. First, the growth mechanism in a ALD system using CpPtMe3 as the precursor was investigated. The growth could be separeted into three regions：(1) Ts < 2500C, a part of precursor was decomposed to form dimethyl platinum which causes steric hindrance on the substrate surface. (2) 2500C < Ts < 3000C：precursor was decomposed to form methyl platinum and matched self-limiting mechanism. (3) Ts > 3500C：precursor was decomposed to form platinum atom and multilayer-adsorption occurred on the surface. Then, a typical ALD Pt deposition condition that applied 5.71×10-4 torr Pt precursor for 3 seconds exposure and [O2] = 28.6% for 2 seconds exposure at 3000C was used for Pt deposition on InN nanostructures. TEM results showed that the deposition of Pt catalyst on InN was polycrystalline and the average diameter of Pt cluster was about 9-11 nm. Decreasing the growth temperature to 2800C showed a better Pt coverage result of slightly (111) oriented on InN nanostructures. A cyclic voltammetry measurement with respect to methanol showed quite a small onset potential at 0.34V, coincident with the value (0.35V) for single crystalline Pt(111).

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38

Lin, Pin-Wei, and 林品緯. "Chemical Bath Deposition of ZnS and Its Application to One-dimensional Sensors." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/28597054796053837690.

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碩士
國立中興大學
材料科學與工程學系所
105
A novel fabrication technique for single crystalline ZnO(002) nanorods has been proposed in this research. First, a chemical-bath deposited (CBD)ZnS thin film was prepared on sapphire substrate. Then, the ZnO was grown by pulsed laser deposition (PLD) on the CBD-ZnS at a substrate temperature of 900 ?C. When the substrate temperature was increased to 900 ?C, the ZnS film can be decomposed to Zn nanoparticles and sulfur fumes. The sulfur fumes were exhausted; meanwhile, Zn nanoparticles were formed on sapphire. The formation of Zn nanoparticles with the hexagonal Zn(002) phase is helpful to grow the single crystalline ZnO(002) nanorods. In comparison to conventional poly-crystalline ZnO nanorods deposited by hydrothermal and vapor–liquid–solid methods, the single crystalline ZnO nanorods presented in this study possess a higher crystal quality. Thus, the metal-semiconductor-metal photodetectors (PDs) fabricated with the single crystalline ZnO nanorods have an excellent optoelectronic performance. The effects of Zn/S ratio and film’s thickness of CBD-ZnS on the ZnO morphology and device performance were also investigated. First, the thickness of ZnS films was fixed at 60 nm, and the Zn/S ratios of 1/50, 1/100, and 1/150 were selected. It can be found that the PLD-ZnO grown the ZnS layer with the Zn/S ratio of 1/100 possessed a more obvious nanostructure. Under a bias voltage of 1 V, the dark currents of the ZnO PDs prepared on the ZnS layers with Zn/S ratios of 1/50, 1/100, and 1/150 were 1.57×10-7, 1.26×10-7, and 2.57×10-8 A, while their photocurrents were measured to be 1.06×10-5, 2.41×10-5, and 8.06×10-7 A, respectively. The signal-to-noise ratios of these three PDs were 67.5, 191.3, and 31.4, respectively. Then, the Zn/S ratio of ZnS film was kept at 1/100, and three thicknesses of 60, 90, and 120 nm were chosen. The dark currents (@1 V) of the ZnO PDs grown on the 60-, 90-, and 120-nm-thick ZnS layers were 1.26 × 10-7, 2.18 × 10-7, and 7.54 × 10-8 A, while their photocurrents (@1 V) were 2.41 × 10-5, 6.25 × 10-5, and 3.75 × 10-6 A, respectively. The signal-to-noise ratios of these three PDs were 191.3, 286.7, and 49.7, respectively. Based on the results, when the Zn/S ratio and thickness of the ZnS film were 1/100 and 90 nm, respectively, the ZnO PD fabricated on the CBD-ZnS possessed the optimum optoelectronic performance.

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39

"Growth of one dimensional Zinc selenide nanostructures by metalorganic chemical vapor deposition." 2004. http://library.cuhk.edu.hk/record=b5892039.

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Leung Yee Pan = 利用有機金屬化學氣相沉積方法生長一維硒化鋅鈉米結構 / 梁懿斌.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references (leaves 80-82).
Text in English; abstracts in English and Chinese.
Leung Yee Pan = li yong you ji jin shu hua xue qi xiang chen ji fang fa sheng chang yi wei xi hua xin na mi jie gou / Liang Yibin.
Acknowledgements --- p.ii
Abstract --- p.iii
Chapter Chapter 1 - --- Introduction --- p.1
Chapter 1.1 --- Background --- p.1
Chapter 1.2 --- Motivation --- p.3
Chapter 1.2.1 --- ZnSe --- p.3
Chapter 1.2.2 --- MOCVD --- p.3
Chapter 1.3 --- Our Work --- p.4
Chapter Chapter 2 - --- Experiment --- p.5
Chapter 2.1 --- MOCVD System --- p.5
Chapter 2.2 --- Metalorganic Sources --- p.5
Chapter 2.3 --- Substrates --- p.7
Chapter 2.4 --- Substrate Preparations --- p.7
Chapter 2.5 --- Preheating (Applied Only when Using GaAs Substrates) --- p.7
Chapter 2.6 --- Growth of Epi-layer (Applied Only when Using GaAs Substrates) --- p.8
Chapter 2.7 --- Growth of ZnSe Nanowires on Si(100) and ZnSe/GaAs(100) --- p.8
Chapter 2.8 --- The Samples --- p.9
Chapter Chapter 3 - --- Characterization --- p.10
Chapter 3.1 --- Surface Morphologies --- p.10
Chapter 3.1.1 --- Scanning Electron Microscopy --- p.10
Chapter 3.1.2 --- Atomic Force Microscopy --- p.12
Chapter 3.2 --- Structural Properties - X-Ray Diffraction --- p.13
Chapter 3.3 --- Optical Properties - Photoluminescence --- p.15
Chapter 3.4 --- Other Techniques --- p.16
Chapter Chapter 4 - --- Results --- p.17
Chapter 4.1 --- ZnSe Nanowires Grown on Si(100) --- p.17
Chapter 4.1.1 --- Effect of Growth Temperature --- p.17
Chapter 4.2 --- Growth of ZnSe Nanowires on GaAs( 100) - The First Trial --- p.20
Chapter 4.3 --- Optimizing the ZnSe Epi-layer --- p.21
Chapter 4.3.1 --- Surface of GaAs(100) --- p.21
Chapter 4.3.2 --- ZnSe Epi-layer Grown at Different Reactor Pressures --- p.22
Chapter 4.4 --- Importance of Au --- p.26
Chapter 4.5 --- Growth of ZnSe Nanowires on GaAs(lOO) - A Systematic Study --- p.28
Chapter 4.5.1 --- Growth Rates --- p.28
Chapter 4.5.2 --- Overall Morphologies --- p.32
Chapter 4.5.3 --- Classifying the Morphologies --- p.37
Chapter 4.5.4 --- Abundances of Different Morphologies of Different Samples --- p.40
Chapter 4.5.5 --- Growth Direction --- p.45
Chapter 4.5.6 --- Structure of the Nanowires --- p.50
Chapter 4.5.7 --- Optical Properties of the Nanowires --- p.54
Chapter Chapter 5 - --- Discussions --- p.57
Chapter 5.1 --- Overview of the MOCVD Process --- p.57
Chapter 5.1.1 --- Effects of Growth Temperature on Growth Rate of MOCVD --- p.58
Chapter 5.1.2 --- Effects of Reactor Pressure on Growth Rate of MOCVD --- p.59
Chapter 5.2 --- Effect of Reactor Pressure on the Growth Rate of the Nanowires --- p.60
Chapter 5.3 --- Growth Mechanisms of the Nanowires --- p.64
Chapter 5.3.1 --- VLS Mechanism --- p.64
Chapter 5.3.2 --- Spiral Growth Mechanism --- p.66
Chapter 5.3.3 --- Reentrant Corner Mechanism --- p.67
Chapter 5.3.4 --- Roles of Au Particles and ZnSe Epi-layer --- p.68
Chapter 5.3.5 --- Growth Mechanisms of Different Types of Nanowires --- p.69
Chapter 5.3.6 --- Effect of Growth Temperature --- p.71
Chapter 5.4 --- Quality of the Nanowires --- p.72
Chapter 5.5 --- "Remarks of the AFM Experiments and the ""Transferred"" Samples" --- p.72
Chapter Chapter 6 - --- Conclusions --- p.75
Appendices --- p.77
Chapter I - --- "Estimation of the mass, other than the nanowires, contributed to the sample" --- p.77
Chapter II - --- Calculation of the growth angle with respect to the surface normal --- p.78
References --- p.80

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40

Shih, Yao-Yin, and 施堯尹. "Preparation of directional one-dimensional ZnO nanorods by atmospheric chemical vapor deposition." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/23duh5.

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碩士
國立東華大學
材料科學與工程學系
96
In this research, we prepared well-aligned ZnO rods which were grown vertically on substrate, by atmospheric chemical vapor deposition method. We discussed the dependence of growth of ZnO rods on two different parameters. We changed the Ⅵ/Ⅱ ratios and the growth temperature in order to study the dependence of morphology and preferred orientation. The result of our experiment shows that high Ⅵ/Ⅱ ratios promote the growth of ZnO rods whereas low Ⅵ/Ⅱ ratios do not promote the growth of ZnO rods. Neither too high nor too low of growth temperatue will not promote the growth of ZnO rods. Finally, With growth rate of 9.11nm/min, substrate temperature of 575℃, and Ⅵ/Ⅱ ratios larger than 5848, we could obtain well-aligned ZnO rods which were grown vertically on substrate.

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41

Ting, sheng-hung, and 丁勝紘. "Synthesis and Characterization of One-Dimensional SnO2 Structure by Chemical Vapor Deposition." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73875678094421622274.

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碩士
逢甲大學
電子工程所
97
In this study, one-dimensional SnO2 nanostructure has been synthesized on ITO/glass substrate via chemical vapor deposition in low temperature with vapor-liquid-solid (VLS) mechanism. Morphology of SnO2 nanowire arrays were observed with field emission scanning electron microscopy (FE-SEM). The crystal structures of the nanowires were identified by X-ray diffraction (XRD) utilizing Cu Kα radiation. Chemical composition of the as-prepared SnO2 nanowire arrays were analyzed by energy dispersive spectrometer (EDS).

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42

Yang, Jen Hung, and 楊仁泓. "Localized Electrochemical Deposition Process and Mechanical Property Measurements for One-Dimensional Structure." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/29732561313097892033.

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碩士
大葉大學
機械工程研究所碩士班
92
In general, electrochemical deposition has been employed to deposit metal on the metallic surface (plating) or to deposit metal for duplicating the patterns prepared by photolithographic process (electroforming). However, if by locally controlling the induced electric field to deposit metal, the lithography process for prepare the pattern by marks can be spared. Thus, it can reduce fabrication cost and error of masks or molds. Furthermore, using a localized electrochemical deposition can deposit micro-sized structures with high aspect ratio easily. Usually, the structure which is fabricated by micro-process, demonstrates mechanical properties different from its bulk materials counterpart. In this study, we use a localized electrochemical deposition to fabricate a cantilever beam of Cu which is in the dimensions of micrometers. The effects of various control parameters of the deposition process are also studied. The first resonance frequency of the deposited structure is measured by the forced vibration at its base. The Young’s modulus of the micro-structure is then inferred from the resonance frequency and several possible factors which affect the apparent stiffness are discussed. Because a stepping mode is used to deposit micro-structure in the experiment, a nodular micro-structure has been obtained. Therefore, this study also design a magnification mechanism which is composed of linkages connected by flexure hinges and is driven by a piezoelectric actuator. The continuous movement instead of stepped movement of the electrode with feedback control, should overcome the shortcoming of the previous study.

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43

Yu, Chi-Chung, and 尤啟中. "Growth of One-Dimensional SiOx and TiO2 Nanostructures Using Chemical Vapor Deposition." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/44011566065347659092.

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碩士
國立成功大學
化學工程學系碩博士班
91
The growth characteristics of one dimensional nc-Si/SiOx composite nanowires using SiCl4/H2 as well as oxygen absorbed on chamber wall in a hot-filament chemical vapor deposition reactor were investigated in this study. The composite nanowires were grown on various substrates by non-VLS mechanism at lower substrate temperatures in comparison with polycrystalline film formed at high temperature. Structural and compositional characterizations of the nanowires by TEM and electron energy-loss spectroscopy (EELS) indicate that dendritic self-assembly of Si nanorods are embedded in the amorphous SiOx nanowires. PL analyses of the nc-Si/SiOx composite nanowires show a blue-green light emission at room temperature. Aligned rutlie and anatase TiO2 nanorods as well as anatase TiO2 nanowalls have been synthesized using a template- and catalyst-free CVD method. Formation of various crystal phases and morphologies of TiO2 nanostructures were dependent on the substrate temperatures as well as the distances between the Ti source and the substrates. Anatase films, nanowalls and well-aligned nanorods were formed at substrate temperatures of 420~485℃, 500~535℃ and 560~605℃, respectively. Rutile nanorods were grown at substrate temperatures of 630~655℃ in a longer distance between Ti source and substrate. TEM analyses indicate that rutile and anatase TiO2 nanorods were both single crystalline. Optical characterizations of the TiO2 nanostructures show that the bandgap of anatase and rutile phase were 3.2 as well as 3.0 eV, respectively.

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44

"Origin of high-grade hematite ores at Thabazimbi Mine, Limpopo Province, South Africa." Thesis, 2009. http://hdl.handle.net/10210/1965.

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M.Sc.
High-grade hematite ores at the Thabazimbi Mine, Limpopo Province, occur as stratabound bodies in the Early Paleoproterozoic Penge Iron Formation of the Transvaal Supergroup. Iron ores occur at three distinct positions in the Penge Iron Formation (i) basal ore bodies located immediately above a thin oxidised shale unit that marks the base of the Penge Iron Formation in the Thabazimbi area and that may be interpreted as a structural contact towards the underlying dolostones of the Malmani Subgroup; (ii) ore bodies developed immediately above a prominent mafic sill in the Penge Iron Formation; (iii) small, lenticular ore bodies developed in the iron-formation without apparent structural control. Ore bodies in all three stratigraphic positions formed on the expense of the Penge Iron Formation protore, they share very similar mineralogical and textural attributes and can be subdivided into three major ore types with respect to their mineralogy and physical characteristics, namely, (a) carbonate-hematite ore; (b) hard hematite ore; (c) supergene modified ore. Further subdivision into subtypes is possible based on textural attributes. The first stage of iron ore formation at the Thabazimbi deposit is marked by oxidation of ferrous minerals (carbonates and grunerite) and their replacement by hematite. Efficient leaching and replacement of chert in the iron-formation to produce high-grade hematite ores characterizes the second stage of alteration. Stable isotope and fluid inclusion evidence point to a hydrothermal origin of the iron ores. Two hydrothermal fluids were identified, namely a highly saline Ca-Mg-rich brine (S = 27 wt% NaClequiv, TH = 160ºC) and a Nadominated fluid of intermediate salinity (S = 10 wt% NaClequiv, TH = 130ºC) that is possibly of meteoric origin. The results obtained in this study are used to propose the following sequence of mineralising events for the Thabazimbi iron ore deposit: (i) Deposition of iron-formation and diagenesis; (ii) contact metamorphic alteration related to the intrusion of the Bushveld igneous complex; (iii) metasomatic oxidation, leaching and residual upgrading that is tentatively linked to structurallycontrolled hydrothermal fluid flow; (iv) supergene modification of existing high-grade ore bodies in post-Gondwana times along the old African land surface.

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45

Yang, Chu-Hao, and 楊筑皓. "Dielectric Barrier Discharge Based Remote Atmospheric Pressure Plasma Deposition for One-step Protein Immobilization." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/qh5xgu.

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碩士
國立交通大學
機械工程系所
107
In recent years, atmospheric pressure plasma (APP) has been widely used for bio-medical applications. APP can achieve non-thermal and mild discharge, reducing the heat influence to bio molecules. Without using vacuum systems, the cost of APP system can become lower. In this study, a dielectric-barrier-discharge based remote APP deposition (DBD RAPPD) system is used for protein immobilization. Since in APP system the deposition is occurred in the discharge region, protein may be denatured or damaged by the factors in the plasma, like heat, reactive species and UV. The deposition region is limited by area of the electrode in APP system. With remote plasma, deposition can occur at the downstream region of the plasma. Influence of plasma on protein can be reduce, large surface treatment and uniform coating can be achieve by this DBD RAPP system. The DBD RAPP system used two parallel plate DBD, which has a 1mm distance between them. Aluminum tapes (50mm x 50 mm) are used as the electrodes. The working gas in plasma is helium, and the precursor is ethylene. The protein we used is BSA (Bovine serum albumin). Helium goes through the atomizer to generate protein aerosol. Ethylene reacts with plasma and becomes plasma-polymerized ethylene (ppE) then deposited onto the substrate. Upstream mixing (mixing BSA aerosol and ethylene before gas going through the discharge region) and downstream mixing (mixing BSA aerosol and ppE at the downstream region outside the discharge) are used for experiments discussions. BSA is immobilized by entrapment of ppE or bonded with functional groups. FTIR was used for analyze the composite of coatings. SEM was used for investigate the morphology of coating surfaces. The coatings were rinsed by micro fluid to detect BSA adhesion. Surface profiler was used to analyze the thickness of coatings. Immunostaining was used for detecting the protein activity. In the result the signal and structure of BSA-ppE coating are detected and remained after rinse. Some appropriate experiment parameters for the immobilization are found.

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46

Hicks, Nigel. "A combined sedimentological-mineralogical study of sediment-hosted gold and uranium mineralization at Denny Dalton, Pongola Supergroup, South Africa." Thesis, 2009. http://hdl.handle.net/10413/1194.

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The ~2.98 - 2.87 Ga Pongola Supergroup in South Africa is subdivided into the lower volcano-sedimentary Nsuze Group, and the upper sedimentary Mozaan Group, the latter comprising a several kilometres thick succession of fluvial to shallow marine sandstones and shales. Thin beds of gold and uranium-bearing conglomerates are locally present in the Mandeva Formation near the base of the Mozaan Group and have been mined at Denny Dalton in northern KwaZulu-Natal. The style of mineralization strongly resembles that of the Witwatersrand goldfields, however appears to be of low grade and limited tonnage. The ~1 m thick basal conglomerate, the “Mozaan Contact Reef” (MCR, herein referred to as CG 1), at Denny Dalton hosts erratic gold and uranium mineralization. The conglomerate is laterally discontinuous and occupies east-northeast trending scour channels. Polymict, matrix-supported conglomerates are common, while clast-supported conglomerates are rare. Well rounded, pebble to cobble-sized clasts of vein quartz and chert are hosted in a sandy matrix of quartz, pyrite and sericite. Where mineralized, the CG 1 hosts abundant rounded pyrite grains, interpreted as detrital in origin, with subordinate U-bearing minerals, such as brannerite and uraniferous leucoxene. Rounded detrital pyrite occurs in three phases, compact, porous and radial. Gold forms inclusions within massive pyrite grains, which are concentrated in shoots associated with the basal parts of the channel scours. SEM-EDX results, as well as the high reflectivity of the gold show a high Ag content, indicative of a primary origin for the gold within the pyrite grains. Uranium within CG 1 is hosted primarily as secondary inclusions of uranium within black chert pebbles within the basal cobble-sized regions of the conglomerate. Geochemical comparison of the chert pebbles at Denny Dalton with similar chert from the Nondweni Greenstone Belt indicates that the uranium is secondary in origin as no U anomalies occur in the Nondweni chert. Geochemical and SEM analysis of the uppermost conglomerate (CG 4) indicate the presence of uraninite and coffinite within the uppermost horizon as both fillings of voids within, and coatings on, detrital pyrite grains. Palaeocurrent data indicate a likely source terrain for the detrital material to the west of the inlier. This orientation, as well as differing mineralogical and sedimentological aspects between the Mandeva Formation and the correlative Sinqeni Formation within the main Pongola basin, indicate a separate and more proximal provenance for the auriferous conglomerates of the White Umfolozi Inlier. The Mandeva Formation is a fluvial to shallow marine sequence that has been affected by cyclic sea-level changes. The basal conglomerates of the Denny Dalton Member were deposited in a proximal braided alluvial plain environment. The conglomerates fine upwards into trough cross-bedded quartz arenites which appear to have been deposited as shallow marine sands in a shoreface environment. They are overlain with a sharp contact by a laterally extensive unit of polymictic conglomerate which represents a transgressive ravinement surface within the wave zone and marks the onset of a major marine transgression into the Pongola basin. The conglomerate is overlain by massive grits and coarse-grained quartz arenite. This unit is overlain with a sharp and locally sheared contact by shales and subordinate banded iron formation which can be traced into other parts of the Pongola basin and indicates continued rapid transgression onto large parts of the Kaapvaal Craton with deeper marine, sub-storm wave base sediments being deposited in quiet-water environments on a sediment-starved shelf. The heavy mineral assemblage as well as bulk geochemical data is consistent with a granitoid-greenstone source terrain for the conglomerates and sandstones. The geochemical composition of chert pebbles from the CG 1 is similar to the composition of cherts present in the Nondweni Greenstone Belt that is situated ~30 km west of the White Umfolozi Inlier. Multiple sulphur isotope (ä34S, ä33S) values for detrital pyrite from the MCR are consistent with an origin from mantle-like rocks, such as hydrothermal sulphide-quartz veins in a granitoid-greenstone setting. Palaeocurrent, mineralogical and geochemical data all point to a likely granitoid-greenstone provenance to the west of the White Umfolozi Inlier.
Thesis (M.Sc.)-University of KwaZulu-Natal, 2009.

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47

Lo, Yu-Chun, and 羅于珺. "Preparation and Applications of One-Dimensional Fluorine-doped Tin Oxide Nanostructure with Vapor-deposition Processes." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/90772350709171450726.

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碩士
國立清華大學
化學工程學系
102
One-dimensional nanostructure is much easily and quickly for electron transfer, therefore many kinds of one dimensional structural materials were developed and used in various fields. Semiconducting SnO2 is a key functional material that has been used extensively for optoelectronic devices and sensors. Because the conductivity of SnO2 is not notable, SnO2 often doped with different atoms in order to improve and enhance the carrier concentration and electrical properties. FTO, fluorine-doped tin oxide, because of its excellent visible light transparency and electric conductivity, has found extensive applications in optoelectronics, display, and photovoltaic devices as a transparent conductive electrode. In this study, we aim to alter the 2-D flat FTO film to fabricate an extended 3-D FTO structure, to increas its surface areas and roughnesses, and effectively shorten the path of electron transfer. In the first part of this study, we developed a vapor-solid (VS) process, to successfully grow 1-D nanocone FTO on commercial FTO substrates for applications in dye-sensitized solar cells (DSSC) as the anode substrate. Through the investigation of the effect of the NH4F／SnCl2‧2H2O ratio in the anode substrate fabrication, we found that the power conversion efficiency (PCE) of the DSSC changed accordingly. When the doping ratio was 0.5, the PCE was slightly enhanced to 6.19 %. As compared with the PEC obtained by using commercial FTO as the anode substrate (5.52 %), the PCE has increased 12%. The good contact between the TiO¬2 and the present 1-D FTO anode substrate led to smaller contact resistances (Rco). This further resulted in a large fill factor of 0.74 and small R1 of 3.72 Ω. In the second part, we developed a vapor-liquid-solid (VLS) process, employing gold nanoparticles as the catalyst, to grow FTO nanowires on commercial FTO substrate. These 1-D FTO structure samples were prepared inside a quartz tube, with flowing N2 and air to adjust oxygen concentration for SnO2 nanowire formation and NH4F as the fluorine source for in-situ F-doping. The products showed low sheet resistances and high hydrophilicity, and thus possessed a great potential for applications in H2O2 sensing through Pt-loading. Because of the poor hydrophilicity of the commercial FTO, the amount of Pt loading was limited, which affected its sensing performance. The nanowire length of sample Au-FTO NWs-3hr was about 750 nm, and was good for Pt loading. This sample showed a high sensitivity of 272 mA/M. This study successfully develops a promising and novel sensing electrode, which is conducting, of high surface area, and highly hydrophilic.

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48

Chen, Reui-San, and 陳瑞山. "Growth Control of Iridium Dioxide One-Dimensional Nanocrystals and Thin Films Using Metal-Organic Chemical Vapor Deposition." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/38448336272257955910.

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博士
國立臺灣科技大學
電子工程系
93
Via the technique of vertical-flow cold-wall metal-organic chemical vapor deposition (MOCVD) using highly volatile (MeCp)(COD)Ir as the CVD precursor, conductive iridium dioxide (IrO2) one-dimensional (1D) nanocrystals, including nanorods (NRs) and nanotubes (NTs), as well as thin films have been successfully deposited on various substrates. A detailed characterization focusing on the morphology, structures, orientations, and compositions of the various IrO2 samples have been carried out by means of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffractometry (SAED), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and Raman scattering. The field emission characteristics of the IrO2 NRs with pointed tips are also studied. The effects of chamber pressure (Pc) and substrate temperature (Ts) on the growth phase transformation from Ir metal, mixed Ir/IrO2 to IrO2 have been observed. The dioxide phase of iridium is found to be preferentially formed under the combined CVD conditions of higher oxygen ambient pressures (Pc = 10 - 50 Torr) and higher temperatures (Ts ³ 350 °C); otherwise iridium metal phase is obtained at either lower pressure (Pc = 1 Torr) or lower temperatures (Ts £ 300 °C). It is worth noting here that IrO2 undergoes a gradual change of crystallization behavior from isotropic 3D particulates to 1D rod-like crystals while lowering the deposition temperatures from 450 to 300 °C at 30 Torr of pressure. IrO2 1D nanocrystals are always obtained at a temperature of 350 °C under a relatively high pressure of 30 Torr. Electrical measurements show the polycrystalline IrO2 films have room temperature resistivity of 80 ± 8 mW-cm. The alignment and density of the IrO2 1D crystals have been improved using titanium (Ti) and indium (In) coated silicon(100) substrates as compared to the direct growth on the bare silicon(100) substrate. The IrO2 1D crystals with vertical alignment and nearly unique (001) out-planed orientation have been reached by depositions on sapphire (SA)(100) and LiNbO3 (LNO)(100) substrates. The analysis of lattice relationship between IrO2(001) plane and (100) plane of sapphire and LiNbO3 shows the in-planed orientation relationship: IrO2[100] // SA[010] and IrO2[100] // LNO[010]. An interesting tilted growth of well aligned IrO2 1D materials has been observed using LiTaO3 (LTO)(012) substrate. The SAED and XRD measurements indicate the epitaxial growth of IrO2 on LTO (012) with the orientation relationship given by IrO2(101)//LTO(012) and IrO2 //LTO[100]. The initial IrO2(101) epitaxial nucleation on the LTO(012) surface was found to be the key factor leading to the growth with a tilt angle ~35°. The tilted growth has been further observed in the IrO2 growth on the other oxide substrates including SA(012), SA(110), LTO(110), yttrium-stabilized ZrO2 (YSZ)(100) and YSZ(111). Among the results of tilted growth, IrO2 1D crystals grown on LTO(012) and SA(012) substrates exhibit singly aligned direction; meanwhile IrO2 on LTO(110) and SA(110) exhibit symmetrically doubly aligned directions. Growth patterns with quadruply and sextuply aligned-directions are observed on the YSZ(100) and (111) substrates, respectively, which is attributed to the lattice relationship between rectangular IrO2(101) plane and square (100) and hexagonal (111) planes of YSZ. From a morphological study, the controlled growth of IrO2 1D nanocrystals, including various NRs and NTs, has been done. The evolution from triangular/wedged NRs, via incomplete/scrolled NTs to hollow square NTs and solid square NRs has been observed as we decrease the growth rates of the 1D materials. Our results show the single-wall NT is more energetically favorable than other tubular forms and the solid square NR is the most stable form for the tetragonal rutile material of IrO2. A spiral mode and the growth rate-dependent kinetics were supposed to be the main mechanism resulting in the morphological evolution. The structural characterization by TEM, SAED and XRD shows the single-crystalline quality and an identical preferred c-axis growth direction for the IrO2 NRs and NTs. The XPS examinations show common stoichiometric characteristics, including the excess oxygen content and a higher oxidation state, for the IrO2 1D material. The micro-Raman spectra show red-shift and peak broadening of the IrO2 signatures with respect to that of the bulk counterpart which may be indicative of a phonon confinement effect for these NTs. The unique geometrical features of IrO2 NRs, including nanosized structure and self-assembled sharp tip, exhibit a strong effect on field enhancement (b ~ 40000), which result in a low threshold field (Eth ~ 0.7 V/mm) defined at the beginning of emission. A low turn-on field for driving a current of 10 mA/cm2 is about 5.6 V/mm, which is comparable with the carbon nanotube, diamond, and amorphous carbon. The potential of using IrO2 nanorods as an emitter material has been demonstrated.

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49

Chen, Chih-jung, and 陳志榮. "Synthesis and Characterization of One-Dimensional Indium Zinc Oxide and Tin Oxide Structure by Chemical Vapor Deposition." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/86152193625492345715.

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博士
逢甲大學
電機與通訊工程所
98
In this study, one-dimensional Indium Zinc Oxide (IZO) and tin oxide (SnO2) nanostructures have been successfully synthesis on ITO glass substrate via chemical vapor deposition in low temperature with vapor-liquid-solid (VLS) mechanism. Morphology of IZO and SnO2 nanowires arrays were observed with field emission scanning electron microscopy (FE-SEM). The IZO nanowires optimal experimental parameters are growth pressure is 1 Torr, argon gas flow of 50 sccm and oxygen flow 10 sccm. In this environment, the idea temperatures are 700 ℃ for indium (In) particles and 550 ℃ for zinc (Zn) particles. Nanowires have uniform diameters of approximately 100 nm to 150 nm, and their lengths are up to tens of 5 μm The SnO2 best growth temperatures are 450 ℃ and growth pressures were 8 × 10-1 Torr, respectively. In the catalyst, the nickel (Ni) catalyst compared to platinum (Pt) catalyst is a more effective reduction of one-dimensional SnO2 nanostructure on the ITO glass, the length of nanowires is about 1 μm ~ 2 μm, under the catalytic reaction conditions and low-temperature growth processes of one-dimensional SnO2 nanostructure on the ITO glass with an average diameter of about 20 nm ~ 50 nm. The X-ray diffraction (XRD) results show that the as-synthesized nanowires are crystalline with highly preferential orientation. Energy dispersive spectrometer (EDS) analysis shows that the composition ratio and confirmed in this material are indeed IZO and SnO2 nanowires.

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50

Chen, Shih-Wei, and 陳世偉. "Morphology Evolution of Co Thin Films during Deposition by DC Magnetron Sputtering and Their Applications for OME Process." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/34874910606785424657.

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碩士
國立成功大學
材料科學及工程學系碩博士班
91
The cobalt thin films are grown by D.C. magnetron sputtering as a function of the target-to-substrate distance, bias and power on both Si (100) and (111) substrates. The crystal structure and morphology of the thin films are characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. It is found that the cobalt crystal structure can be varied from HCP to FCC by varying the target—to-substrate distance from 6 to 10 cm. The roughness and the preferred orientation of the thin films are greatly affected by the substrate bias and power. In addition, pyramid-like nanostructures with sharp tips are formed on the surface of the thin films when negative bias is applied. The faceted planes on the nanostructures depend on the resulting Co crystal structure while the size and density are determined by the growth parameters. The evolution of the surface nanostructures are systematically examined as a function of substrate bias and thin film thickness. The formation mechanism of the surface nanostructures is discussed in the paper. We use D.C. magnetron sputtering to form CoSi2 by OME (Oxide-Mediated Epitaxy) Process. Thickness of Co films is sensitive for OME process, we can get uniform Co film about 3~6 nm by sputtering. Growth difference of CoSi2 can be varied by using different parameter, like annealing by two steps that are 460℃ for 60 seconds and 600℃ for 60seconds, substrate be implanted more silicon, and design the sandwich structure of OME process.CoSi2 thin film can grow uniform by sandwich structure and annealing by two steps.

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