Dissertations / Theses on the topic 'Glasse'
To see the other types of publications on this topic, follow the link: Glasse.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Glasse.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Yu, Xiao Quan. "Superfluidity and localization in Bosonic glasses." Doctoral thesis, SISSA, 2012. http://hdl.handle.net/20.500.11767/4785.
Full textAbstract:
Bosonic excitations within long-range ordered, but strongly inhomogeneous phases have been studied in quite some detail. My thesis focuses instead on understanding the insulating, localized phase of disordered bosonic systems. In particular I study localization properties of strongly interacting bosons and spin systems in a disorder potential at zero temperature. I focus on simple, prototypical spin models (Ising model and XY model) in random fields on a Cayley tree with large connectivity. Regarding the nature of the quantum phase transition in strong disorder I find the following results: i) With a uniformly distributed disorder non-extensive excitations in the disordered phase are all localized. ii)Moreover, I find that the order arises due to a collective condensation, which is qualitatively distinct from a Bose Einstein condensation of single particle excitations into a delocalized state. In particular, in non-frustrated Bose glasses, I do not find evidence for a boson mobility edge in the Bose glass. These results are qualitatively different from claims in the recent literatures . Considering that (many body) localization of bosons is a kind of quantum glass transition, it is an interesting question to ask what phenomena occur, if the ingredients for more conventional (classical) glassy physics are added to a disordered bosons system, namely: random, frustrated interactions between the bosons. One can still think about such a system as bosons in a disordered potential, where the disordered potential is, at least partly, self-generated by random frustrated interactions between the bosons. This question takes us to the study of another type of disordered systems: glassy systems. Those are typically characterized by low temperature phases with an inhomogeneous density or magnetization pattern, which is extremely long-lived due
to the occurrence of non-trivial ergodicity breaking. I study a solvable model of hard core bosons (pseudospins) subject to disorder and frustrating interactions. This solvable model provides insight into the possibility of coexistence of super uidity and glassy density order, as well as into the nature of the coexistence phase (the superglass). In particular, for the considered mean field model I prove the existence of a superglass phase. This complements the numerical evidence for such phases provided by quantum Monte Carlo investigations in finite dimensions and on random graphs. Those were, however, limited to finite temperature, and could thus not fully elucidate the structure of the phases at T = 0. In contrast, my analytical approach allows one to understand the quantum phase transition between glassy superfluid and insulator, and the non-trivial role played by glassy correlations. When the frustrated interactions are strong enough, the superfluid order may be destroyed. As I will show in a mean field model, this happens within the glass phase of the system, where a disorder induced superfluid-insulator phase transition takes place to give way to a frustrated Bose glass. The glassy background on top of which this happens leads to many interesting phenomena which seem not to have been noticed before. To understand the nature of the glassy superfluid-insulator quantum phase transition at zero temperature and the transport properties on the insulating, Bose glass side of the transition is the goal of the third part of my thesis. To address the above questions, I studied an exactly solvable model of a glassy superfluid-insulator quantum phase transition on a Bethe lattice geometry with high connectivity. My main results can be summarized as follows: i) I found that the superfluid-insulator transition is shifted to stronger hopping. This is a result of the pseudo gap in the density of states of the glass state, which tends to strongly disfavor the onset of superfluidity. ii) In the glassy insulator, the discrete local energy levels become broadened due to the quantum fluctuations.The level-broadening process appears as a phase transition which has strong similarities with an Anderson localization transition, and has implications on many body localization. By using the locator expansion for bosons I found that, the glassy insulator has a finite mobility edge for the bosonic excitations, which, however, does not close upon approaching the SI quantum phase transition point. This finding helps to understand the nature of the superfluid-to-frustrated Bose glass transition: the superfluid emerges as a collective phase ordering phenomenon at zero temperature, and not as a condensation in to a single particle delocalized state, in contrast to opposite predictions in the recent literatures. The existence of a mobility edge in the insulator suggests the possibility of phononless, activated transport in the bosonic insulator, which might be a candidate explanation for the experimentally seen activated transport, which has remained a mystery for a long time.
2
MUZI, ELISA. "Advanced nanostructured optical glasses and glass-ceramics for photonic applications." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2970993.
Full text
3
Glasse, Benjamin [Verfasser]. "Monitoring of Metal Working Fluid Emulsion Quality by in-process Light Spectroscopy / Benjamin Glasse." Berlin : epubli GmbH, 2015. http://d-nb.info/1074331206/34.
Full text
4
SPARTA', DEBORAH. "REE-BEARING CARBONATE SYSTEMS AT HIGH PRESSURE:AN EXPERIMENTAL STUDY." Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/910101.
Full textAbstract:
Abstract
REE bearing carbonate systems at high pressure: an experimental study
Carbonatites are important sources of Rare Earth Elements (REE). REE mainly reside in Ca-bearing phases carbonates, apatites, Ca-Nb oxides, Ca-silicates and in accessory phases such as monazite, burbankite, bastnäsite. At liquid phases, carbonate melts display remarkable physical properties. In particular, carbon-rich and silica-poor melts, i.e. transitional melts, are efficient metasomatizing agents of carbon between the mantle and the crust.
This study focuses on two main issues: I) the effect of REE such as La and Y on the structure and melting behavior of transitional carbonate-silicate melts, which has been investigated in simple model with variable CaCO3:SiO2 ratio at 1 GPa; and II) the stability and mineral physics of REE-bearing carbonates at high pressure, in particular of La-burbankite.
Few experimental works have explored phase relations, structure and the role of REE in carbonate-rich melts. The typical unquenchable nature of carbon-rich melts makes for a difficult, determination of the structure of carbon-rich glasses. Wyllie and Jones (1986) synthesized a REE-bearing carbonatite glass in a series of experiments performed in the system CaO–CaF2–BaSO4–CO2–H2O–La(OH)3 using a composition similar to carbonatites ore deposits in Mountain Pass (California). At 0.1 GPa the investigated carbonatite composition starts to melt at temperatures as low as 550°C. As today, there are no data available regarding melting behavior, structural properties of melts, and the stability of REE-bearing phases in model system of hydrous carbon-rich low silica. Furthermore, although in alkali free systems a complete miscibility between silicate and carbonate liquids is expected, the compositional threshold at which carbonate-silicate liquids might form a glass, i.e. are quenchable, is still scarcely explored in simple model systems. In this study, I investigated i) how viable is the quenching of a carbon-rich melt as a function of the bulk SiO2:CaCO3 ratio, ii) the structure of these glasses, iii) and the role of REE in the molecular structure(La, Y). I also determined the CO2 solubility in transitional melts by micro-Raman spectroscopy. Single stage and end-loaded piston cylinder experiments have been performed at 1 GPa in two model systems: CaO–SiO2–La2O3–H2O–CO2 in the range 700–1250°C, and CaO–SiO2–Y2O3–H2O–CO2 in the range 1200–1250°C. The starting materials were prepared as a powder mixture of La2(CO3)3 or La2O3 or Y2O3 and amorphous SiO2 and CaCO3 with approximately 5-10 wt.% of H2O. Different bulk compositions with different SiO2:CaCO3 ratio have been considered. Run products were characterized by backscattered electrons images (BSE), X-ray diffractometry, micro-Raman spectroscopy, nuclear magnetic resonance (NMR) of selected experiments, and chemically analyzed by electron microprobe. At subsolidus conditions (T < 1000°C), all bulk compositions in CaO–SiO2–La2O3–H2O–CO2 system contain calcite and quartz coexisting with a Ca-La silicate phase with an apatite-type structure of general formula between La3Ca2(Si3O12)OH and La4Ca(Si3O12)O. Liquidus conditions have been observed in runs on bulk compositions with SiO2:CaCO3 = 0.28 1.4 at T >1150°C for both investigated systems. Homogeneous quenched glasses have been retrieved for composition with up to SiO2:CaCO3=0.28 ratio, whereas at lower ratio (0.12) dendritic textures are visible. Deconvolution of Raman spectra of glasses reveal a CO2 content up to 20.40% in the CaO–SiO2–La2O3–CO2–H2O system and up to 10.80% in the CaO–SiO2–Y2O3–CO2–H2O system classifying the melts as carbonate-silicate transitional melt.
While studiyng the behavior of Ca-rich carbonatitic hydrous glasses with REE, we also investigated the influence on the REE distribution of an alkaline carbonate, burbankite [(Na,Ca)3(Sr,Ba,Ce,REE)3(CO3)5], at upper mantle conditions. Recently, the alkaline-carbonate system has been observed at High Pressure and High Temperature (HP-HT) by Shatzky et al., (2016); they found a new class of Ca-rich alkaline-alkaline earth carbonates and burbankite with the latter being abundantely presents in carbonatites that constitutes important ore concentrations of strategic metals, including Nb and REE elements on Earth’s surface. A La rich burbankite [Na3Ca2La(CO3)5] was synthesized at 5 GPa and 1000°C, to scope out the possibility that REE can enter the structure of this carbonate also at upper mantle conditions. Furthermore, the elastic properties of the synthesized La-burbankite have been determined by in-situ HP and HT single crystal X-ray diffraction measurements at synchrotron facilities using a diamond-anvil cell for HP experiments and a quartz-glass capillary for the HT experiments. The determination of these thermoelastic parameters allowed to calculate the possible density of this phase at upper mantle conditions, that is ca. 3.2 g/cm3 at 5.5–6.0 GPa and 900–1000°C. Results suggest that potentially the La-burbankite could fractionate at HP and HT from a carbonatitic melt, because the latter has a lower density (ca. 2.1-3.1 g/cm3) and may constitute a REEs reservoir at upper mantle conditions.
5
BOETTI, NADIA GIOVANNA. "Nd3+ doped phosphate glass optical fibre lasers." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2543408.
Full textAbstract:
In this thesis a Nd3+-doped phosphate glass was developed in-house in order to obtain a glass stable, robust, able to incorporate high amount of RE ions and suitable for fibre drawing. Several Nd3+-doped phosphate glass samples were fabricated by doping the developed host glass with concentrations of Nd3+ up to 10 mol%. The samples were then characterized in order to measure their physical, thermal and spectroscopic properties. The effect of Nd3+ doping concentration on emission spectra and lifetimes was investigated in order to study the concentration quenching effect on luminescence performance.
With the aim to fabricate a Nd3+-doped double cladding (DC) optical fibre laser emitting at 1.06 µm, three different phosphate glasses using a custom designed glass composition, were fabricated. By changing properly the concentration and constituents present in our phosphate glass, the refractive indexes of the three glasses were adjusted in order to obtain an adequate numerical aperture between core and inner cladding, and between inner and outer cladding, while maintaining similar thermo-mechanical properties in view of the fibre drawing process.
A Nd3+-doped DC optical fibre was fabricated by preform drawing using a drawing tower facilities available in the research group laboratory. Morphological and optical characterisation of the fibre were carried out in order to evaluate fibre quality.
In order to optimize Nd3+-doped fibre laser design, a numerical analysis of the lasers was performed.
At last, a CW cladding pumped fibre laser based on 9 cm of fabricated Nd3+-doped optical fibre was experimentally demonstrated.
6
Leuzzi, Luca. "Thermodynamics of glassy systems glasses, spin glasses and optimization /." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/66345.
Full text
7
Wootton, Andrew Michael. "Silicon oxycarbide glasses and glass-ceramics." Thesis, University of Warwick, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310015.
Full text
8
SCARPIGNATO, GERARDO CRISTIAN. "Design, fabrication and characterization of a optical power amplifier based on special glasses for LIDAR sources." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2543142.
Full textAbstract:
The objective of the present research is the study, fabrication and characterization of a power amplifier based on special glasses to be implemented as an embedded module inside a pulsed laser device with high coherence working at 1550 nm wavelength. The optical amplifier represents the second module of a laser in configuration MOPA (Master Oscillator Power Amplifier).
The device must amplify the signal proceeding from a seed laser and allow
the propagation of the signal at high distances while maintaining the spectral characteristics of the high coherent source. The device obtained with this approach will be employed as a source for a monitoring LIDAR system, which will be installed in train monitoring portals. The results can be
extended to other applications as well, such as aeroplanes, meteorological
stations or airports. The current research work is intended to contribute to
the fabrication of compact devices that seems not be still available even in
laboratories.
9
PONTREMOLI, CARLOTTA. "Mesoporous bioactive glasses as smart platform to stimulate bone regeneration." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2875741.
Full text
10
BARI, ALESSANDRA. "Ion-containing mesoporous bioactive glass particles for tissue applications." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2753212.
Full text
11
Rappensberger, Csaba Ferenc. "Novel rare-earth aluminosilicate glasses and glass-ceramics." Thesis, University of Warwick, 1996. http://wrap.warwick.ac.uk/56937/.
Full text
12
Zhang, Endang. "Fibre reinforcement of oxynitride glasses and glass-ceramics." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320017.
Full text
13
Brüning, Ralf. "Structural relaxation and the glass transition in metallic glasses." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74345.
Full textAbstract:
This thesis presents for the first time direct structural measurements of both reversible and irreversible structural relaxation and the glass transition in the metal-metalloid glass Pd$ sb{40}$Ni$ sb{40}$P$ sb{20}$. The techniques have been x-ray diffraction and Mossbauer spectroscopy, and a new analysis method for changes of amorphous diffraction patterns was developed.It is found that irreversible relaxation proceeds by many local shear-type motions involving the metal atoms, and that it is accompanied by a small densification. Reversible relaxation at high annealing temperatures entails the same microscopic processes, but it does not change the density of the glass. The type of atomic processes changes continuously as the annealing temperature is lowered, and at sufficiently low temperatures the distribution of metal atoms remains constant, so that reversible relaxation then proceeds via rearrangement of the metalloid atoms. This rearrangement leads to more ordered, but less isotropic atomic sites.
The second part of the thesis is concerned with the motion of the atoms in a metallic glass below and above the glass transition. Mossbauer spectroscopy allows the direct measurement of vibrational and diffusional motion. The increase of the amplitude of atomic vibration has the same temperature dependence as the increase in volume that marks the glass transition, thus the two processes are governed by the same mechanism. The directly measured diffusional motion is in agreement with macroscopic measurements of diffusion.
14
De, Mestral François. "Calcium phosphate glasses and glass-ceramics for medical applications." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65405.
Full text
15
Kansal, Ishu. "Diopside-fluorapatite-wollastonite based bioactive glasses and glass-ceramics." Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14827.
Full textAbstract:
Doutoramento em Ciência e Engenharia dos MateriaisBioactive glasses and glass–ceramics are a class of biomaterials which elicit special response on their surface when in contact with biological fluids, leading to strong bonding to living tissue. This particular trait along with good sintering ability and high mechanical strength make them ideal materials for scaffold fabrication. The work presented in this thesis is directed towards understanding the composition-structure-property relationships in potentially bioactive glasses designed in CaOMgOP2O5SiO2F system, in some cases with added Na2O. The main emphasis has been on unearthing the influence of glass composition on molecular structure, sintering ability and bioactivity of phosphosilicate glasses. The parent glass compositions have been designed in the primary crystallization field of the pseudo-ternary system of diopside (CaO•MgO•2SiO2) – fluorapatite (9CaO•3P2O5•CaF2) – wollastonite (CaO•SiO2), followed by studying the impact of compositional variations on the structure-property relationships and sintering ability of these glasses. All the glasses investigated in this work have been synthesized via melt-quenching route and have been characterized for their molecular structure, sintering ability, chemical degradation and bioactivity using wide array of experimental tools and techniques. It has been shown that in all investigated glass compositions the silicate network was mainly dominated by Q2 units while phosphate in all the glasses was found to be coordinated in orthophosphate environment. The glass compositions designed in alkali-free region of diopside – fluorapatite system demonstrated excellent sintering ability and good bioactivity in order to qualify them as potential materials for scaffold fabrication while alkali-rich bioactive glasses not only hinder the densification during sintering but also induce cytotoxicity in vitro, thus, are not ideal candidates for in vitro tissue engineering. One of our bioglass compositions with low sodium content has been tested successfully both in vivo and in preliminary clinical trials. But this work needs to be continued and deepened. The dispersing of fine glass particles in aqueous media or in other suitable solvents, and the study of the most important factors that affect the rheology of the suspensions are essential steps to enable the manufacture of porous structures with tailor-made hierarchical pores by advanced processing techniques such as Robocasting.
Os vidros e vitrocerâmicos bioactivos são uma classe de biomateriais que induzem uma resposta especial à sua superfície quando em contacto com fluidos biológicos que conduz a uma forte ligação ao tecido vivo. Esta característica particular conjugada com uma boa aptidão para a sinterização e elevada resistência mecânica torna estes materiais ideais para a fabricação de estruturas de suporte à regeneração óssea. O trabalho apresentado nesta tese pretende dar um contributo para uma melhor compreensão das relações entre composição-estrutura-propriedades em vidros potencialmente bioactivos com composições no sistema CaOMgOP2O5SiO2F, em alguns casos com a adição de Na2O. O estudo da influência exercida pela composição do vidro na estrutura molecular, capacidade de sinterização e nível de bioactividade dos vidros fosfosilicatados foi objecto de especial atenção. As composições vítreas foram concebidas no campo da cristalização primária do pseudo sistema ternário do diópsido (CaO•MgO•2SiO2) – fluorapatite (9CaO•3P2O5•CaF2) – wollastonite, e estudou-se o impacto das variações composicionais na estrutura, nas propriedades e na capacidade de sinterização destes vidros. Todos os vidros investigados neste trabalho foram preparados por fusão e fritagem e caracterizados quanto à sua estrutura molecular, capacidade de sinterização, degradação química e bioactividade, usando uma grande variedade de técnicas experimentais. Ficou demonstrado que em todas as composições de vidro investigadas a rede de silicato era dominada principalmente por unidades Q2 enquanto o fosfato se encontrava coordenado em ambiente de ortofosfato. As composições de biovidros isentas de alcalinos do sistema diópsido–fluorapatite demonstram possuir excelente capacidade de sinterização e elevados níveis de bioactividade, atributos que os qualificam como materiais promissores para a fabricação de estruturas de suporte à regeneração de tecidos ósseos, enquanto os vidros bioactivos contendo alcalinos foram mais difíceis de densificar durante a sinterização e induziram citotoxicidade in vitro, não sendo candidatos ideais para a engenharia de tecidos. Uma das nossas composições de biovidro com um baixo teor de sódio foi testada com sucesso tanto in vivo como em ensaios clínicos preliminares. Mas este trabalho precisa de ser continuado e aprofundado. A dispersão de fritas moídas em meio aquoso ou outros solventes adequados, e o estudo dos factores mais relevantes que condicionam a reologia das suspensões são etapas essenciais para viabilizar o processo de fabrico de suportes porosos com estruturas hierárquicas de poros feitas por medida através de técnicas de processamento avançadas tais como o Robocasting.
16
Goel, Ashutosh. "Clinopyroxene based glasses and glass-ceramics for functional applications." Doctoral thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2323.
Full textAbstract:
Doutoramento em Ciência e Engenharia de MateriaisAs piroxenas são um vasto grupo de silicatos minerais encontrados em muitas rochas ígneas e metamórficas. Na sua forma mais simples, estes silicatos são constituídas por cadeias de SiO3 ligando grupos tetrahédricos de SiO4. A fórmula química geral das piroxenas é M2M1T2O6, onde M2 se refere a catiões geralmente em uma coordenação octaédrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catiões numa coordenação octaédrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catiões em coordenação tetrahédrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclínica são designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composições químicas amplo, em conjugação com a possibilidade de ajustar as suas propriedades físicas e químicas e a durabilidade química, têm gerado um interesse mundial devido a suas aplicações em ciência e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicações funcionais. O estudo teve objectivos científicos e tecnológicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formação de fases cristalinas e soluções sólidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicação dos novos materiais em diferentes áreas tecnológicas, com especial ênfase sobre a selagem em células de combustível de óxido sólido (SOFC). Com este intuito, prepararam-se vários vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsídio (CaMgSi2O6) e diopsídio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados através de um vasto leque de técnicas. Todos os vidros foram preparados por fusão-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterização e cristalização de fritas, quer por nucleação e cristalização de vidros monolíticos. Estudaram-se ainda os efeitos de várias substituições iónicas em composições de diopsídio contendo Al na estrutura, sinterização e no comportamento durante a cristalização de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicação como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos à base de enstatite não apresentavam as características necessárias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos à base de diopsídio qualificaram-nos para futuros estudos neste tipo de aplicações. Para além de investigar a adequação dos vitro-cerâmicos à base de clinopyroxene como selantes, esta tese tem também como objetivo estudar a influência dos agentes de nucleação na nucleação em volume dos vitro-cerâmicos resultantes á base de diopsídio, de modo a qualificá-los como potenciais materiais hopedeiros de resíduos nucleares radioactivos.
The pyroxenes are a wide spread group rock-forming silicate minerals found in many igneous and metamorphic rocks. They are silicates that, in their simplest form, contain single SiO3 chains of linked SiO4 tetrahedra. The general chemical formula for pyroxenes is M2M1T2O6, where M2 refers to cations in a generally distorted octahedral coordination (Mg2+, Fe2+, Mn+, Li+, Ca2+, Na+), M1 to cations in a regular octahedral coordination (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), and T to tetrahedrally coordinated cations (Si4+, Al3+, Fe3+). Monoclinic pyroxenes are called clinopyroxenes. The stability of clinopyroxenes over a broad spectrum of chemical compositions, in conjunction with the possibility of achieving desired physical properties and high chemical durability, has generated a worldwide interest due to their applications in material science and technology. The present work deals with the development of clinopyroxene based glasses and glass-ceramics for functional applications. The objective of the study was dual, both scientific and technological; particularly to gain fundamental knowledge on the formation of crystalline phases and solid solutions in selected glass-ceramic systems, and to evaluate the feasibility for application of new materials in different technological areas with emphasis on sealing in solid oxide fuel cells (SOFC). In this pursuit, various glasses and glass-ceramics along Enstatite (MgSiO3) - Diopside (CaMgSi2O6) and Diopside (CaMgSi2O6) – Ca – Tschermak (CaAlSi2O6) joins have been prepared and characterized by a wide array of characterization techniques. All the glasses were prepared by melt-quenching technique while glass-ceramics were produced either by sintering and crystallization of glass powders or by nucleation and crystallization in monolithic glasses. Furthermore, influence of various ionic substitutions/additions in Alcontaining diopside on the structure, sintering and crystallization behaviour of glasses and properties of resultant glass-ceramics has been investigated, in relevance with final application as sealants in SOFC. It has been observed that enstatite based glasses/glass-ceramics do not exhibit requisite characteristics in order to qualify for the job of sealing in SOFC while the superior properties exhibited by diopside based glass-ceramics qualify them for further experimentation as SOFC sealants. Apart from investigating the suitability of clinopyroxene based glass-ceramics as sealants, this thesis also aims to study the influence of nucleating agents on the volume nucleation in the resultant diopside based glass-ceramics so as to qualify them for further experimentation as hosts for radioactive nuclear wastes.
17
Medina, Francelys A. Lanagan Michael Thomas. "Impedance spectroscopy studies of silica-titania glasses and glass-ceramics." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-4566/index.html.
Full text
18
Mao, Ming. "Structural relaxation and the glass transition in metal-metal glasses." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41708.
Full textAbstract:
This thesis presents the results of a systematic study on the structural relaxation and the glass transition of ternary metal-metal glasses Zr$ sb{67}$(Ni$ sb{1-x}$Cu$ sb{x}) sb{33}$. Differential scanning calorimetry provides macroscopic evidence of structural changes from the compositional and temperature dependence of enthalpy change. Results from high precision x-ray diffraction and Mossbauer spectroscopy, performed mainly on $ rm Zr sb{67}Ni sb{10}Cu sb{23}$ (x = 0.7), complete the picture of structural changes at the atomic level.Irreversible structural relaxation leads to densification and enthalpy release. Shear-like atomic motion enhances local atomic order, highlighting the atomic processes during the irreversible relaxation. Reversible structural relaxation involves two partly overlapping processes initiated at different temperatures, which are characterized by the solid and liquid atomic mobilities, respectively. Interatomic positional exchanges between Cu and Ni atoms change the local structure and are active during the reversible relaxation at low temperatures, which are also partly responsible for the irreversible relaxation. Above 500 K, shear-like atomic movements characterize the reversible relaxation, involving all three atomic species in a length scale of a few near-neighbor atomic shells. The overall density is unchanged during reversible relaxation.
The strong compositional dependence of the glass transition in the ternary glasses indicates an intimate association of the glass transition with interatomic bondings among different atomic species. The atomic motion from room temperature up to above the glass transition temperature, measured by the Mossbauer spectroscopy, is macroscopically tracked by the volume expansion and the enthalpy evolution. The glass transition occurs when the length scale of the atomic motion expands so rapidly that the interatomic potential can no longer maintain the on-site atomic vibration. The rapid development of translational atomic motion upon approaching the glass transition is reflected by the dramatic enhancement of the diffusive atomic motion.
19
Żalin̄ska, Beata. "Bismuth-based glasses, glass-ceramics and composites for microwave applications." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.537987.
Full text
20
Beatty, Kirk Matthew 1962. "Processing of copper aluminosilicate glasses to produce glass-copper structures." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/278284.
Full textAbstract:
Copper aluminosilicate (composition Cu₂O·Al₂O₃·6SiO₂) glass was melted in an alumina crucible at 1500°C and air cooled in situ. A layer of cupric oxide was grown on the polished glass surface and its thickness measured using a scanning electron microscope (SEM). The thickness of the oxide layer was found to increase parabolically with time, with a temperature dependency that was compatible with the diffusion of copper through the layer. The cupric oxide layer was reduced to copper on roughened and polished glass surfaces using a gas mixture of 3% H₂ and 97% N₂, resulting in a glass substrate coated by copper. Adherence of the copper layer to the polished glass substrate was found to be poor. However, adherence was found to increase by roughening the surface before oxidation. Additions of NiO and CaO to the base glass were not detrimental to the production of the copper film.
21
Williams, Kyle Fiona Eirwen. "Moessbauer spectroscopic studies of tin in glass." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283059.
Full text
22
Huang, Hong. "Synthesis and devitrification of high glass-forming ability bulk metallic glasses." Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/842676/.
Full textAbstract:
In this thesis, literature on the production, microstructures and properties of bulk metallic glasses (BMG) has been reviewed with particular reference to glass forming ability (GFA) and alloys of the Fe-Zr-B and Zr-based BMG systems. The experimental procedures used in the research are presented and the results for the amorphous Fe80Zr12B8 ribbon and the Zr57Ti5Al10Cu20Ni8, Zr57Nb5Al10Cu20Ni8, Zr53Nb2Al8Cu30Ni7 BMGs are given and discussed. Wedge-shaped ingots of the Zr-based BMGs were produced by casting in air or water cooled copper moulds. The Zr-based BMGs were fully amorphous up to 2 mm thickness of the wedge. In the Fe80Zr12B8 alloy and the Zr-based BMGs the glass transformation and crystallization temperatures increased with increasing temperature increase rate in the DSC. This shows that atom mobility dominates the onset of crystallization. Using XRD and TEM, the crystallization of the Fe80Zr12B8 amorphous alloy was studied from room temperature to 1273 K. The phase evolution path during continuous heating was: Amorphous → amorphous + alpha-Fe → amorphous + alpha-Fe + Fe23Zr6 (Fe3Zr) → amorphous + alpha-Fe + Fe23Zr6 (Fe3Zr) + Fe2Zr → amorphous + alpha-Fe + Fe23Zr6 (Fe3Zr) + Fe2Zr + Fe3B. In the air-cooled Zr57Ti5Al10Cu20Ni8 alloy the A1 rich Zr3Al2 and the bcc Al1.5(Cu+Ni)3(Zr+Ti)5 phases were quenched in the amorphous matrix and as the temperature decreased nanocrystalline Zr3Al2 phase nucleated. It is suggested that A1 is critical regarding GFA. The main crystalline phase that contained Zr, Ti, Al, Cu and Ni was the tetragonal (Zr, Ti)2(Cu, Al, Ni) phase, which is isomorphous with the Zr2Cu phase. Compared with the air-cooled alloy, the water-cooled amoiphous Zr57Ti5Al10Cu20Ni8 alloy has a larger supercooled liquid region and the same reduced glass transition temperature. This would suggest that fine crystallites were probably present in the air-cooled amorphous Zr57Ti5Al10Cu20Ni8 alloy. Thermal stability and GFA increased with the substitution of Ti with Nb in Zr57Nb5Al10Cu20Ni8 and the increase of the Cu/Nb ratio in Zr53Nb2Al8Cu30Ni7. Increase of the Cu/Nb ratio in Zr-based BMGs improved the GFA criteria, the thermal stability, hardness and eliminated crack formation. It is suggested that the Zr-Ti/Nb-Al-Cu-Ni BMGs with high glass forming ability can be obtained over a wide composition range Zr = 50-60 at.%, Ti or Nb = 2-5 at.%, A1 ≤ 8 at.%, Cu+Ni ≥ 30 at.%. On the basis of the results of this study on the formation of the primary crystallization phase, it is suggested that atomic packing close to the amorphous phase, high melting temperature and strong bonding among component elements lead to the ease of formation of the primary phase. In terms of reliability and applicability, good glass formers should capture the following features: low Ti, high Tg and high (Tx-Tg). Good indicators are made of ratios and sums of ratios that reflect these features. New GFA indicators are proposed namely: Tx/Tg + Tx/T1, Tx/(T1-Tg) + Tx/Tg, Tx/Tg + Tg/T1 +Tx/T1, (Tx-Tg)/T1 + Tx/T1. Casting at specific cooling rate or annealing at temperature between the glass transition temperature (Tg) and onset crystallization temperature (Tx), especially annealing near Tx for enough time, leads to the formation of nanoparticles in an amorphous matrix.
23
Ponsot, Inès. "Glasses and Glass-Ceramic Components from Inorganic Waste and Novel Processing." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424636.
Full textAbstract:
Thanks to European environmental rules and regulations establishment, waste recycling has become a more and more relevant problematic. For manufacturing plants, especially those producing hazardous wastes, expenses linked to waste production have drastically increased over the last decades. In the proposed work, various hazardous and non-hazardous wastes, among: soda-lime and borosilicate glass cullet, cathode ray tubes glass, exhausted lime from fume abatement systems residues, sludge and slags from ferrous and non-ferrous metallurgy, and pre-stabilized municipal solid waste incinerators ashes are used to elaborate several compositions of glass-ceramics. High-temperature treatment (minimum 800 °C) associated to a Direct Sintering process (30 min) was an efficient way to stabilize chemically the final products. The impact of each waste on the final product’s mechanical properties was studied, but also their synergies between each other, when mixed together. Statistic mixture designs enabled to develop interesting products for modern building applications, such as porous tiles and lightweight panels destined to insulation, with a purpose of fulfilling multifunctional properties.Grazie alle regole e normative ambientali europee istituite, il riciclaggio dei rifiuti è diventato una problematica sempre più rilevante. Per gli impianti di produzione, in particolare quelli che producono rifiuti pericolosi, le spese connesse allo smaltimento sono drasticamente aumentate negli ultimi decenni. Nel lavoro proposto, vari rifiuti, pericolosi o no, vengono utilizzati per elaborare diverse composizioni di vetroceramiche. Si distinguono rottami di vetro della produzione di finestre, di contenitori farmaceutici e di tubi catodici. I rifiuti non vetrosi invece sono calce esausta da residui di sistemi di filtrazione di fumi, scorie metallurgiche da leghe ferrose e non e ceneri da inceneritori. E' presentata nel presente lavoro la ricerca di un metodo di trattamento ad alta temperatura (minima 800 ° C) efficace per stabilizzare chimicamente il prodotto finale, tramite i diversi processi di sinterizzazione diretta, sinter-cristallizzazione e vetrificazione. Sono stati studiati gli effetti di ogni rifiuto sulle proprietà meccaniche del prodotto finale, ma anche le nuove funzionalità ottenute attraverso le sinergie risultanti dalla loro miscela. Miscele calibrate hanno permesso di sviluppare prodotti interessanti per applicazioni edilizie moderne, come le piastrelle porose e pannelli leggeri destinati all’isolamento.
24
Mahfoudhi, Mohamed. "Eu3+ ion environment modification by Electron and femtosecond laser irradiation in metaphosphate and polyphosphate glasses." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX066.
Full textAbstract:
Les verres phosphates dopés terres rares (TR) sont des matériaux attractifs en optique en raison de leur basse température de transition vitreuse et de leur grande capacité à dissoudre les ions de terres rares par rapport aux verres silicates. Dans ce travail, nous sommes intéressés à comprendre les mécanismes conduisant à la modification structurale des verres polyphosphates de zinc et métaphosphates sous irradiation avec pour finalité de contrôler l'environnement des ions terres rares (ions Eu3+ en particulier) par l’irradiation. Nous avons comparé les effets obtenus sous irradiations aux électrons et par laser fs en faisant varier la dose et l’énergie des électrons (700 keV et 2.5 MeV), le taux de répétition du laser ainsi que les compositions de verre qui comportent différents ions alcalins et alcalino-terreux (Na, Li, K et Mg) et teneurs en Zn.Nous avons mis en évidence la diminution de la symétrie du site Eu3+, l’augmentation de la dispersion des sites ainsi qu’une réduction efficace des ions Eu3+ en Eu2+ sous irradiation électronique.La présence de Zn atténue la variation de l’ordre local autour de la terre rare, alors que le réseau vitreux est moins stable sous irradiation. La formation d’ion Eu2+ (sous deux types d’environnement de haute et basse symétries est par ailleurs accrue en présence de Zn et en utilisant des électrons de 700 keV. Le laser femtoseconde à 10 KHz engendre une cristallisation des verres métaphosphates sans réduction des ions Eu3+Rare Earth (RE) doped phosphate glasses are attractive materials in optic due to their low glass transition temperature and their high ability to dissolve rare earth ions compared to silicate glasses. In this work, we are interested in understanding the mechanisms leading to the structural modification of zinc polyphosphate and metaphosphate glasses under irradiation with the aim of controlling the environment of rare earth ions (in particular Eu3+ ions) by irradiation. We compared the effects obtained under electron and femtosecond laser irradiation by varying the dose and electron energy (700 keV and 2.5 MeV), the laser repetition rate as well as the glass compositions that contain different alkaline and alkaline earth ions (Na, Li, K and Mg) and Zn contents.We have demonstrated the decrease of the Eu3+ site symmetry, the increase of the sites dispersion as well as an effective reduction of Eu3+ to Eu2+ under electron irradiation.The presence of Zn attenuates the variation of the local order around the rare earth, while the vitreous network is less stable under irradiation. The formation of Eu2+ ions (under two types of high and low symmetry environments) is further enhanced in the presence of Zn and using 700 keV electrons. The femtosecond laser at 10 KHz gives causes crystallization of metaphosphate glasses without reduction of Eu3+ ions
25
Kemp, Andrew Patrick. "The electrical and other physical properties of haloborate glasses and glass-ceramics." Thesis, University of Warwick, 1988. http://wrap.warwick.ac.uk/109948/.
Full textAbstract:
The effect of a series of classical nucleating agents upon the nucleation and mechanical properties of anhydrous borax (AB,Na2B407) glasses and glass-ceramics have been investigated. These results have been compared to those obtained for NaCl-doped compounds and a commercial B”-Al2O3 ceramic to examine the applicability of haloborate glass-ceramics as a solid electrolyte in high temperature sodium-sulphur cell. The nucleation of these materials was found to be predominantly surface oriented. A new technique has been introduced to increase the number of surface nucleation sites. Direct and indirect structural comparisons of these materials have been carried out using X-ray diffraction and infra-red and Raman spectroscopy. Results from the NaCI-doped materials have tentatively indicated that the chlorine atom plays a direct structural role. Subtle modifications to the structure are thought to results in previously determined high ionic conductivities. A variety of techniques have been examined for the measurement of ionic conductivities based on time and frequency domain spectroscopy. A frequency domain measurement system has been designed and built and a computer program written to analyse the acquired data. Equipment exploring a complementary technique based on the multiple disc stacking arrangement postulated by Tubandt has been built. Results from these two techniques appear promising.
26
DIANAT, BEHNOOD. "Vetri calcogenuri per applicazioni di commutazione di memorie con particolare riguardo agli aspetti di modellazione e simulazioni." Doctoral thesis, Università degli studi di Modena e Reggio Emilia, 2021. http://hdl.handle.net/11380/1244338.
Full textAbstract:
In questo lavoro, esaminiamo inizialmente la caratterizzazione e i difetti dei materiali ad alta costante dielettrica (high-k) La2O3 e CeO2, utilizzati come materiali di ossido di gate nei MOSFET. Presentiamo una metodologia basata sulla simulazione, fondata su una descrizione accurata dell'intrappolamento e del trasporto di carica utile per estrarre informazioni rilevanti sulle caratteristiche del materiale e dei difetti. Questa metodologia è stata applicata ai materiali dielettrici high-k ossido di cerio e ossido di lantanio ricavando, di conseguenza, le proprietà del materiale, insieme alle caratteristiche dei difetti. Di conseguenza, il meccanismo principale di conduzione della carica in tutto il dispositivo è stato identificato nel tunneling assistito da trappole (TAT).
Quindi nel secondo capitolointroduciamo uno script-tool Python per l'estrazione e la caratterizzazione autonoma di parametri statistici relativi a materiali disordinati. Lo scopo del progetto è stabilire una metodologia per l'analisi strutturale dei materiali calcogenuri amorfi a cambiamento di fase. Il codice utilizza le librerie e le funzioni standard di NumPy e Pandas, accettando in ingresso le traiettorie della struttura atomica standard o la configurazione ottenuta dai calcoli relativi alla dinamica molecolare. Successivamente, il tool calcola le distanze e gli angoli interatomici tramite l'analisi della traiettoria, consentendo quindi di estrarre parametri come: parametro d’ordine q, un dettagliato numero di coordinazione, funzioni di distribuzione radiale e angolare, statistiche sulla popolazione locale e coordinate d’ordine locali nei formati PDB e XYZ. Inoltre, il codice è agnostico sia rispetto al codice che ha generato la singola configurazione o traiettoria, che rispetto agli elementi della struttura.
Successivamente, il terzo capitoloindaga a fondo le strutture gerarchiche di ordine a breve e medio raggio nei vetri amorfi per applicazioni di selettori. Il nostro studio include un'analisi approfondita della relazione tra i meccanismi di legame e le proprietà fisiche risultanti. Impiegando la dinamica molecolare, studiamo le caratteristiche strutturali come gli ordini locali a corto raggio, sia della fase liquida che di quella amorfa, nei sistemi binari di calcogenuro GexSe1-x nel intervallo 0,4
27
G??n, B??lent Materials Science & Engineering Faculty of Science UNSW. "Crystallization behaviour and rheological properties of a Mg-Cu-Y bulk metallic glass." Awarded by:University of New South Wales. Materials Science & Engineering, 2008. http://handle.unsw.edu.au/1959.4/43352.
Full textAbstract:
A repetitive low-pressure die casting technique has been developed for casting high quality Mg6SCU2SY10 bulk metallic glass (BMG) samples. Using these as-cast samples, the thermal and mechanical behaviour of the BMG in the supercooled liquid (SCL) region was investigated principally by uniaxial tensile testing, differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using the die casting facility, charge temperature, injection pressure and injection velocity were found to be important parameters for controlling the length, porosity and degree of crystallinity in the as-cast samples. A processing map was generated which showed that a melt temperature and casting pressure in the range 560-580°C and 0.4-0.5 bar, respectively, generated the highest quality samples. The static crystallization behaviour of the as-cast BMG was investigated in detail. It was found that the kinetics of both anisothermal and isothermal crystallization were adequately represented by a number of transformation models. Using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) relation in conjunction with isothermal DSC, the Avrami exponent was found to vary from 2.2 to 2.5 with increasing annealing temperature which implies that, at high annealing temperatures, nucleation occurs at a constant rate accompanied by diffusion-controlled growth of spherical grains. A comparable Avrami exponent of 2.34 was also calculated by anisothermal DSC using the Ozawa method. The tensile flow behaviour of the BMG was investigated over a range of strain rates (10.3to 10.1S•1) and deformation temperatures (150 to 170 QC) in the SCL region using standardized tensile test samples. It was found that, the flow stress increased rapidly to a maximum value followed by a decrease to a very low steady-state value. In the SCL region, the relationship between peak flow stress, strain rate and absolute deformation temperature was described adequately by the classic Sellars-Tegart constitutive relationship. There was also a good correlation between the Zener-Hollomon parameter, Z, and the flow characteristics of the BMG such as the transition from Newtonian to non-Newtonian flow at Z>1 031 S•1 and optimum superplasticity for Z-values in the range 5 x 1030 to 5 x 1031 S•1 where tensile elongations in excess of 1400% were achieved.
28
Veligatla, Medha. "Glass Forming Ability, Magnetic Properties, and Mechanical Behavior of Iron-Based and Cobalt-Based Metallic Glasses." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699947/.
Full textAbstract:
Lack of crystalline order and microstructural features such as grain/grain-boundary in metallic glasses results in a suite of remarkable attributes including very high strength, close to theoretical elasticity, high corrosion and wear resistance, and soft magnetic properties. In particular, low coercivity and high permeability of iron and cobalt based metallic glass compositions could potentially lead to extensive commercial use as magnetic heads, transformer cores, circuits and magnetic shields. In the current study, few metallic glass compositions were synthesized by systematically varying the iron and cobalt content. Thermal analysis was done and included the measurement of glass transition temperature, crystallization temperature, and the enthalpies of relaxation and crystallization. Magnetic properties of the alloys were determined including saturation magnetization, coercivity, and Curie temperature. The coercivity was found to decrease and the saturation magnetization was found to increase with the increase in iron content. The trend in thermal stability, thermodynamic properties, and magnetic properties was explained by atomic interactions between the ferromagnetic metals and the metalloids atoms in the amorphous alloys. Mechanical behavior of iron based metallic glasses was evaluated in bulk form as well as in the form of coatings. Iron based amorphous powder was subjected to high power mechanical milling and the structural changes were evaluated as a function of time. Using iron-based amorphous powder precursor, a uniform composite coating was achieved through microwave processing. The hardness, modulus, and wear behavior of the alloys were evaluated using nano-indentation.
29
Masoud, Muayad. "Diffusivity and ionic conductivity in lithium niobate and related glasses and glass composites." [S.l.] : [s.n.], 2005. http://edok01.tib.uni-hannover.de/edoks/e01dh05/504933442.pdf.
Full text
30
Zheng, Na. "Ni-free Ti-based Bulk Metallic Glasses: Glass Forming Ability and Mechanical Behavior." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-119765.
Full textAbstract:
Metallic glasses are amorphous alloys that do not possess long-range structural order in contrast to crystalline alloys. Ni-free Ti-based bulk metallic glasses (BMGs) have potential for biomedical applications due to their attractive properties such as high strength, good corrosion resistance and excellent micro-formability, which cannot be obtained for conventional crystalline alloys. In this PhD thesis, Ni-free Ti-based BMGs, i.e. Ti40Zr10Cu34Pd14Sn2 and Ti40Zr10Cu36-xPd14Inx (x = 0, 2, 4, 6, 8), were prepared in the shape of rods by suction casting. Both alloy classes were systematically characterized in terms of glass forming ability, thermal stability, phase formation and mechanical properties. The largest diameter obtained in the fully glassy state for Ti40Zr10Cu34Pd14Sn2 alloy is 3 mm and for Ti40Zr10Cu36-xPd14Inx (x = 2, 4, 6, 8) alloys is 2 mm. Base alloy (Ti40Zr10Cu36Pd14) contains some crystalline phase(s) in the glassy matrix for a 2 mm diameter rod.
The structural transformations of Ti40Zr10Cu34Pd14Sn2 BMG upon heating were thoroughly analyzed by utilizing different combination of methods. Firstly, we used differential scanning calorimetry (DSC), X-Ray diffraction (XRD) and transmission electron microscopy (TEM) to investigate the first crystallization event. The main products of the first crystallization are possibly -(Ti, Zr) and Cu3Ti (orthorhombic) phases. Secondly, we employed in situ x-ray diffraction in transmission mode using synchrotron beam to deeply study the thermally-induced structural changes like relaxation, glass transition and crystallization. Since the first peak in the diffraction patterns reflects the structure of the glassy phase on the medium-range scale, the position, width and intensity of this peak in diffraction patterns are fitted through Voigt function below 800 K. All the peak position, width and intensity values show a nearly linear increase with increasing temperature to the onset temperature of structural relaxation, Tr = 510 K. However, these values start to deviate from the linear behavior between Tr and glass transition temperature Tg. The changes in the free volume, which was arrested during rapid quenching of the BMG, and the coefficient of volumetric thermal expansion prove that the aforementioned phenomenon is closely related to the structural relaxation. Above 800 K, three crystallization events are detected and the first exothermic event is due to the formation of metastable nanocrystals.
For the Ti40Zr10Cu34Pd14Sn2 alloy, 2 mm diameter rods exhibit the best combination of mechanical properties (e.g. large plastic strain and high yield strength) among all the diameters (ø2, ø3 and ø4 mm) under the room-temperature compression tests. With the aim to improve its room-temperature mechanical properties, the processes of pre-annealing and cold rolling have been applied for the 2 mm diameter rods. Annealed and quenched specimens below Tg and in the supercooled liquid region (between Tg and onset crystallization temperature Tx) do not lead to the enhancement of the plasticity compared to as-cast alloys due to annihilation of excess free volume and crystallization. Cold rolling can effectively improve the plasticity of this BMG by inducing structural heterogeneities. Rolled samples up to a thickness reduction of 15% result in the largest plasticity of 5.7%. Low yield strength and visible work hardening ability are observed in the both 10%-rolled and 15%-rolled samples. The deformation behavior of Ti40Zr10Cu34Pd14Sn2 BMG at the elevated temperatures slightly below Tg and in the supercooled liquid region has been investigated. The stress-strain relations for this BMG over a broad range of temperatures (298 ~716 K) and strain rates (10-5 to 10-3 s-1) were established in uniaxial compression. Under compression tests at the highest test temperature of 716 K, the Ti-based BMG partially crystallizes and low strain rates can lead to the formation of larger volume fractions of crystals.
In order to further improve the plasticity of Ti-Zr-Cu-Pd BMGs and simultaneously reduce the content of Cu (considering harmful element for the human body), the Ti40Zr10Cu36-xPd14Inx (x = 2, 4, 6, 8) BMGs have been newly developed with different short- or medium-range order in the structure. The compressive global strain of Ti40Zr10Cu36-xPd14Inx (x = 0, 2, 4, 6, 8) can be significantly improved from 4.5% for the In-free alloy to 10.2% for x = 4. However, a further increase of the indium content to 8 at.% results in a decrease of the plasticity. Among all the monolithic Ni-free Ti-based BMGs reported so far, the novel Ti40Zr10Cu32Pd14In4 BMG shows the largest plasticity.
Inspired by the dislocation concept in crystalline materials, we propose a strategy for the design of ductile BMGs through minor substitution using relatively large atoms, which make the bonding nature become more metallic and with it less shear resistant. Such a locally modified structure results in topological heterogeneity, which appears to be crucial for achieving enhanced plasticity. This strategy is verified for Ti-Zr-Cu-Pd glassy alloys, in which Cu was replaced by In, and seems to be extendable to other BMG systems. The atomic-scale heterogeneity in BMGs is somewhat analog to defects in crystalline alloys and helps to improve the overall plasticity of BMGs.
31
Kanwal, Nasima. "Novel zinc containing phosphate glasses for glass-ionomer cements for bone cement applications." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8440.
Full textAbstract:
Glass‐ionomer cements (GICs) are acid base reaction cements used in dentistry for restorative applications. In conventional GICs aluminosilicate glass is used to react with a polyalkenoic acid such as poly acrylic acid. Glass–ionomer cements have the potential to be used for bone cement applications, however there is a concern over the neurotoxicity of aluminium in the glass component of these cements. In this work zinc containing phosphate glass based glass–ionomer cement has been developed for the bone cement application. In this relation structure of zinc containing phosphate glasses in the system Na2O:CaO:ZnO:P2O5 ranging from metaphosphate compositions to invert phosphate compositions has been examined. Various advanced techniques in solid state nuclear magnetic resonance (NMR) such as dipolar recoupling and solid state NMR of low quadrupolar nuclei (67Zn and 43Ca) and neutron diffraction have been employed. Special emphasis has been focused on structural role of zinc in glasses of different composition and the effect of different cations on coordination of zinc along with the effect on phosphate tetrahedra. 67Zn and 43Ca solid state NMR spectra of selected glass samples have been successfully acquired at ultrahigh field 900 MHz using Solid Echo pulse sequence. In addition solid state NMR spectra of two polymorphs of crystalline Zn(PO3)2 have also been acquired at 850 MHz using DFS– WURST–QCPMG pulse sequence in order to distinguish between the magnitude and orientation of electric field gradient (EFG) of zinc in octahedral and tetrahedral coordination. Structure determined through various techniques has been related to the dissolution behaviour of glass compositions from metaphosphate to invert phosphate. A decrease in pH of surrounding medium has been observed due to the presence of zinc. Insertion of ZnO4 tetrahedra between PO4 tetrahedra has been observed in invert phosphate glasses with high zinc oxide content which renders them suitable for glass– ionomer cements. Glass–ionomer cement from glass composition 10Na2O:50ZnO:10CaO:30P2O5 and hydroxyapatite and, acrylic acid and vinyl phosphonic acid co‐polymer has been produced successfully.
32
Sulaiman, Ismail. "Approches fondamentales et expérimentales des processus d'autovaporisation et de modification structurelle de matériaux surchauffés pendant la détente instantanée controlée vers le vide." Phd thesis, Université de La Rochelle, 2013. http://tel.archives-ouvertes.fr/tel-01066134.
Full textAbstract:
La modification de la structure des matériaux par Détente Instantanée Contrôlée (DIC), implique nécessairement un processus d'autovaporisation instantanée en conditions thermodynamiques extrêmes de surchauffe du liquide. Les divers processus DIC de modification de la structure par expansion contrôlée, d'extraction et de refroidissement instantané sont d'un intérêt particulier. Les conditions opératoires et les caractéristiques spécifiques du produit interagissent mutuellement pour aboutir au meilleur résultat, principalement en termes de texture. Les modifications des caractéristiques structurelles généralement traduites par des taux d'expansion du produit, dépendent donc des conditions opératoires et des propriétés thermiques et rhéologiques de la matière. De nombreuses études initiales ont montré l'intérêt de déterminer l'évolution des divers processus à travers un suivi et un enregistrement instantané des images, des températures et de la pression à l'échelle de 1000 unités par seconde ; il a ainsi été indispensable de mettre en opération une caméra ultra rapide à 1000 images / s, des capteurs de température et de pression à temps de réponse de l'ordre du ms, placés dans le réacteur et au sein du produit. Une analyse fondamentale a prouvé l'importance de la thermodynamique, du transfert et de la problématique d'expansion pendant le traitement. L'analyse des expériences est réalisée par la détermination des taux d'expansion, surfacique et volumique, de la durée du processus d'expansion proprement dite, de l'analyse des caractéristiques micro-structurelles par MEB, mais principalement par la détermination de la température de transition vitreuse, de la différence de température minimale et d'ébullition, et du taux d'échange de chaleur. Plusieurs produits ont été étudiés (fromage, tofu, pomme, pomme de terre, carotte et banane). Des essais préliminaires adéquats ont permis d'identifier les domaines de variation des paramètres opératoires et d'adopter la méthode des plans d'expériences rota tables à cinq niveaux pour quantifier les diverses réponses nécessaires.
33
Aykol, Muratahan. "Nano-scale Phase Separation And Glass Forming Ability Of Iron-boron Based Metallic Glasses." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609825/index.pdf.
Full textAbstract:
This study is pertinent to setting a connection between glass forming ability (GFA) and topology of Fe-B based metallic glasses by combining intimate investigations on spatial atomic arrangements conducted via solid computer simulations with experimentations on high GFA bulk metallic glasses. In order to construct a theoretical framework, the nano-scale phase separation encountered in metallic glasses is investigated for amorphous Fe80B20 and Fe83B17 alloys via Monte Carlo equilibration and reverse Monte Carlo simulation. The phenomenon is identified regarding three topological aspects: 1) Pure Fe-clusters as large as ~0.9 nm and Fe-contours with ~0.72 nm thickness, 2) Fe-rich highly deformed body centered cubic regions, 3) B-centered prismatic units with polytetrahedral order forming distinct regions of high and low coordinations are found. All topological aspects are compiled into a new model called Two-Dimensional Projection Model for predicting contributions to short and medium range order (MRO) and corresponding spacing relations. The outcome geometrically involves proportions approximating golden ratio. After successfully producing soft magnetic Fe-Co-Nb-B-Si based bulk metallic glass and bulk nanocrystalline alloys with a totally conventional route, influences of alloying elements on structural units and crystallization modes are identified by the developed model and radial distributions. While Co atoms substitute for Fe atoms, Nb and Si atoms deform trigonal prismatic units to provide local compactions at the outset of MRO. Cu atoms alter the type of MRO which resembles crystalline counterparts and accompanying nanocrystals that precipitate. The GFA can be described by a new parameter quantifying the MRO compaction, cited as Φ
.
34
Hadzifejzovic, Emina. "Electrical and structural aspects of Li-ion conducting phosphate based glasses and glass ceramics." Thesis, Queen Mary, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408396.
Full text
35
Galstyan, Ani. "The role of glass modifiers in the solubility of Tm3+ ions in As2S3 glasses." Doctoral thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27110.
Full textAbstract:
Au cours des années une variété des compositions de verre chalcogénure a été étudiée en tant qu’une matrice hôte pour les ions Terres Rares (TR). Pourtant, l’obtention d’une matrice de verre avec une haute solubilité des ions TR et la fabrication d’une fibre chalcogénure dopée au TR avec une bonne qualité optique reste toujours un grand défi. La présente thèse de doctorat se concentre sur l'étude de nouveaux systèmes vitreux comme des matrices hôtes pour le dopage des ions TR, ce qui a permis d'obtenir des fibres optiques dopées au TR qui sont transparents dans l’IR proche et moyenne. Les systèmes vitreux étudiés ont été basés sur le verre de sulfure d'arsenic (As2S3) co-dopé aux ions de Tm3+ et aux différents modificateurs du verre. Premièrement, l'addition de Gallium (Ga), comme un co-dopant, a été examinée et son influence sur les propriétés d'émission des ions de Tm a été explorée. Avec l'incorporation de Ga, la matrice d’As2S3 dopée au Tm a montré trois bandes d'émission à 1.2 μm (1H5→3H6), 1.4 μm (3H4→3F4) et 1.8 μm (3F4→3H6), sous l’excitation des longueurs d'onde de 698 nm et 800 nm. Les concentrations de Tm et de Ga ont été optimisées afin d’obtenir le meilleur rendement possible de photoluminescence. À partir de la composition optimale, la fibre Ga-As-S dopée au Tm3+ a été étirée et ses propriétés de luminescence ont été étudiées. Un mécanisme de formation structurale a été proposé pour ce système vitreux par la caractérisation structurale des verres Ga-As-S dopés au Tm3+, en utilisant la spectroscopie Raman et l’analyse de spectrométrie d'absorption des rayons X (EXAFS) à seuil K d’As, seuil K de Ga et seuil L3 de Tm et il a été corrélé avec les caractéristiques de luminescence de Tm. Dans la deuxième partie, la modification des verres As2S3 dopés au Tm3+, avec l'incorporation d'halogénures (Iode (I2)), a été étudiée en tant qu’une méthode pour l’adaptation des paramètres du procédé de purification afin d’obtenir une matrice de verre de haute pureté par distillation chimique. Les trois bandes d'émission susmentionnées ont été aussi bien observées pour ce système sous l'excitation à 800 nm. Les propriétés optiques, thermiques et structurelles de ces systèmes vitreux ont été caractérisées expérimentalement en fonction de la concentration d’I2 et de Tm dans le verre, où l'attention a été concentrée sur deux aspects principaux: l'influence de la concentration d’I2 sur l'intensité d'émission de Tm et les mécanismes responsables pour l'augmentation de la solubilité des ions de Tm dans la matrice d’As2S3 avec l’addition I2.Over the years a number of chalcogenide glass compositions have been studied as host matrices for Rare Earth (RE) ions. However, it still remains a great challenge to obtain a glass matrix with high solubility of RE ions and to fabricate a RE doped chalcogenide glass fiber with good optical quality. The present PhD thesis focuses on the study of new glassy systems as host matrices for doping of RE ions, which allowed to obtain RE doped optical fibers transparent in near and middle IR. Studied glassy systems were based on well-known arsenic sulphide (As2S3) glasses co-doped with Tm3+ ions and different glass modifiers. Firstly, the addition of Gallium (Ga) ions as co-dopants was examined and their influence on the emission properties of Tm ions was explored. With the incorporation of Ga into the host, Tm doped As2S3 glasses display three strong emission bands at 1.2 μm (1H5→3H6), 1.4 μm (3H4→3F4) and 1.8 μm (3F4→3H6) under excitation wavelengths of 698 nm and 800 nm. Despite the very small glass forming region of the system Ga-As-S we could optimise the concentration ratio of Ga and Tm to achieve the highest possible photoluminescence efficiency. From the optimal composition, Tm3+ doped Ga-As-S fiber was drawn and its luminescence properties were studied. Through structural characterisation of Tm doped Ga-As-S glasses, using Raman spectroscopy and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at As K-edge, Ga K-edge and Tm L3-edge, a formation mechanism has been proposed for this glassy system and it was correlated with luminescence features of Tm ions. In the second part, the modification of Tm3+ doped As2S3 glasses with the incorporation of halides (namely Iodine (I2)) was investigated, as a method for tailoring the process parameters for purification, in order to obtain a high purity glass matrix via chemical distillation. All three of above mentioned emission bands were observed for this system as well, under the 800 nm of excitation wavelength. Optical, thermal and structural properties of these glassy systems were characterized experimentally depending on the concentration of I2 and Tm in the glass, where the attention was concentrated on two principal aspects: the influence of the concentration of I2 on the intensity of emission of Tm and the mechanisms responsible for the increase of the solubility of Tm ions in As2S3 glass matrix with addition of I2.
36
Fredholm, Yann Christophe. "Development and characterisation of strontium-containing bioactive glasses and aluminium-free glass polyalkenoate cements." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/6201.
Full textAbstract:
Bioactive glass (BG) reactivity is the result of a special silicate structure, disrupted by the presence of alkali and earth-alkali metal ions. These glasses dissolve in body fluids and form a hydroxy-carbonated apatite (HCA) on their surface, which mimics the composition and structure of the mineral phase of bone. This feature, coupled with the release of biologically active ions, explains their excellent osseointegration. In the first part of this thesis, we investigated the effect of substituting strontium for calcium in a BG system based on SiO2-P2O5-Na2O-CaO. The reason for introducing strontium in a BG was driven by its strengthening effect on bone in the treatment of osteoporosis. The glass structure and physical properties were investigated by X-ray diffraction (XRD), solid state nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and thermal analysis. Dissolution profiles and in vitro bioactivity of Sr-BG were investigated in Tris buffer and simulated body fluid by inductively coupled plasma (ICP) spectroscopy, XRD and FTIR. Glass cytotoxicity was assessed by culturing osteoblast-like cells (SaOs-2) on Sr-BG discs for 14 days. It was found that substitution of Sr for Ca does not modify the Q2 silicate structure of the glass, nor its orthophosphate environment. However, it expands and weakens the glass network, thus the glasses dissolved more rapidly with higher strontium content and formed more HCA. A live/dead cellular assay showed an increased cell proliferation for higher strontium containing glasses. Glass polyalkenoate cements (GPCs) also use the potential of reactive glasses to release multivalent cations, which cross-link the carboxylic groups of polyacid chains in aqueous solution to form a hard cement. GPCs do not shrink, do not have significant exotherm and have good adhesive properties. However, the use of commercial GPCs, based on fluoro-alumino-silicate glasses, has been limited to dentistry and minor surgery due to biocompatibility issues. Aluminium is known to have neurotoxic effect and inhibits remineralisation. The aim of the second part of this study was to investigate new glass compositions for the development of aluminium-free GPCs for orthopaedic applications. Sr-BG compositions were adapted for cement forming purpose by removing soda and including Mg2+, Zn2+ and Fe3+ to provide an alternative to Al3+. The selected cations are all naturally present in the body and can potentially enter into the glass network, mimicking the formation of Al- O-Si bonds present in conventional GPCs. The mechanical properties of the cements were assessed by performing compression and bonding strength tests, whereas their working (WT) and setting times were measured with an oscillating rheometer. Finally, cement cytotoxicity was evaluated by culturing SaOs-2 cells on cement discs. It was established that only high zinc containing glasses lead to cements with suitable mechanical properties to be used as bone cements. WT was short but increased up to two minutes by using citric acid as a chelating agent. The high Zn release from the cements induced cytotoxicity and predominated over the potential positive effect of Sr on cells.
37
Uhlmann, Eugenie Victoria. "Glass forming ability, structure and spectroscopic properties of silica-free calcium aluminate based glasses." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187097.
Full textAbstract:
Calcium aluminate based glasses are interesting because of their unusual optical properties and the fact that they do not contain any traditional glass forming ions. A large focus of the glass literature has been concerned with the study and properties of typical glass forming ions. For this reason, comparatively little is known about the possibility of glass formation and the structure and properties in unusual systems. The present work will describe the limits of glass formation within the calcium aluminate system. The use of non-silicate based stabilizing additives will also be detailed. It has been demonstrated that certain additions to the calcium aluminate system will improve the glass formation tendency without impairing the desired optical properties. The effects of various ions and their impact on the processing and properties of the glasses will be described in the framework of traditional theories of glass formation. Additional optical properties of the calcium aluminate system have also been investigated. Using the Judd-Ofelt model, various spectroscopic properties of calcium aluminate based glasses have been calculated. The stimulated emission cross section, branching ratios, intensity parameters and transition probabilities show interesting variations with compositional manipulations. Attempts to improve the emission cross section will also be described. The structure of calcium aluminate based systems has been studied using NMR and Raman Spectroscopy. The coordination of alumina has been examined with respect to compositional changes. In addition, structural studies have been conducted on calcium aluminate glasses synthesized by the sol-gel method. This method has allowed the formation of higher alumina content glasses. The evolution of structure with heat treatment temperature was followed and a comparison between melt-derived and sol-gel prepared glasses has been made.
38
Drewitt, James W. E. "Structure of copper halide melts, rare earth chalcogenide glasses and glassy germania at high pressure." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516958.
Full text
39
Kusumoto, Hiroko. "Characterisation of Mg, Sr, and Zn containing fluoro-aluminosilicate glasses and their glass polyalkenoate cements." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5509.
Full textAbstract:
The glass polyalkenoate cements (GPCs) are formed by the acid-base reaction between fluoro-aluminosilicate glasses and polycarboxylic acid in the presence of water. Three series of glasses were produced by modifiying glass LG26 [32.1SiO2. 21.4Al2O3. 10.7P2O5. 21.4CaO. 14.3CaF2] (mole %). In the first series, calcium was substituted by magnesium, and in the second series, calcium in the first series was substituted by strontium. The last series were zinc substitution for calcium in LG26. These glasses were characterised by X-ray diffraction (XRD), magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy and differential scanning calorimetry (DSC). The gradual substitution of calcium by magnesium resulted in the formation of F-Mg(n) species and a disappearance of Al-F species on the 19F MAS-NMR. The 31P and 27Al MAS-NMR showed that all glasses contained Q1 pyrophosphate Al-O-PO3 3- species. In addition, the fully magnesium substituted glass showed the possible formation of magnesium pyrophosphate, Mg2P2O7. The fully zinc substituted glass, however, showed only Al-O-PO3 3- species charge balanced by Zn2+. An increase in Al(V) species was observed on the 27Al MAS-NMR with the fully magnesium and zinc substituted glasses. The presence of magnesium also increased the number of bridging oxygen on SiO4 tetrahedra, but the presence of zinc affected the Q structure of the aluminosilicate network less. GPCs with these glasses were formed with poly (acrylic acid) (PAA) and L-(+)-tartaric acid. The setting reaction of selected cements was studied by 19F, 31P and 27Al MAS-NMR spectroscopy. F-Ca(n) species were clearly shown to be consumed for cement formulation, and F-Mg(n) species were still present in the 19F MAS-NMR spectra of the magnesium containing cements. The Al-O-PO3 3- species were present in the cement. The conversion to Al(VI) from Al(IV) and Al(V) was observed by deconvoluting the 27Al MAS-NMR spectra. The experimental ratio of Al(VI):Al(IV)+Al(V) was higher than the theoretical ratio which may have resulted from the possibility of L-(+)-tartaric acid being involved in the Al conversion during the setting reaction. The working and setting times increased with magnesium substitution, but did not change with zinc substitution for calcium. The compressive strengths decreased with magnesium substitution, possibly resulting from the preferential crosslinking between Mg2+ and COO-. The highest release of fluoride was observed from the fully magnesium substituted cements. Another series of glasses [34.0SiO2. 22.6Al2O3. 5.7P2O5. (22.6-x)SrO. xZnO. 15.1SrF2] (mole %) was produced for formulating GPCs with poly (γ-glutamic acid), PgGA. All the glasses have Al-O-PO3 3- species with no change in the phosphorus environment with zinc substitution for strontium. Al(IV) was found to be the major aluminium species with a small presence of Al(V) and Al(VI). The Q structures of all the glasses were found to be a mixture of Q4(4Al) and Q3(3Al). Similarly, DSC showed a negligible change with zinc substitution for strontium. For cement formulations with PgGA, a co-polymer of PAA and poly (but-3-ene 1,2,4- tricarboxylic acid) was used due to the lower reactivity of PgGA than PAA, and cements with different proportions of PgGA and the co-polymer were formed. The working and setting times increased with PgGA content and zinc substitution. On the contrary, the compressive strengths decreased with PgGA content. The highest zinc containing cements in the series showed the highest compressive strength. A longterm fluoride release measurement showed the highest release from the highest PgGA containing cements, possibly resulting from the cements being less crosslinked. There was a slight increase in the adhesion to dentine.
40
Xie, Fangtong [Verfasser], Emanuel [Akademischer Betreuer] Ionescu, and Aldo R. [Akademischer Betreuer] Boccaccini. "Bioactive Silicon Oxycarbide Based Glasses & Glass-ceramics / Fangtong Xie ; Emanuel Ionescu, Aldo R. Boccaccini." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://d-nb.info/1207075566/34.
Full text
41
Stolpe, Moritz [Verfasser]. "Synchrotron x-ray diffraction studies of bulk metallic glass forming liquid and glasses / Moritz Stolpe." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1218075481/34.
Full text
42
Lepine, Eric. "GLASSES AND GLASS-CERAMICS TRANSPARENT IN THE INFRARED RANGE TO BE USED AS OPTICAL SENSORS." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/193808.
Full textAbstract:
The present work deals with the study of infrared transparent glasses and their applications for sensor use. Their behavior under LASER irradiation, as well as the possibility to modify the surface, and the exploration of new glass compositions has been studied. Four tasks were completed with the main goal of designing infrared optical sensors. In a first task, the deposition of various thin films at the surface of a chalcogenide glass has been investigated in order to produce nano porous surfaces. Films were produced by vapor deposition and cathodic sputtering. Vapor deposition did not produce homogeneous films while cathodic sputtering lead to layers of controlled thickness which could produce a porous surface by selective etching. In a second task, the possibility of writing waveguide with femtosecond laser was investigated in Ge-Ga-S/Se-CsCl glasses. It was shown that high power leads to negative index changes unfit for light guiding, while low power lead to small positive index change. It was also shown that the filamentation method lead to homogeneous waveguide with large positive index changes. In a third task, photo-induced phenomena were investigated, especially photo-induced fluidity, on the binary system Ge-Se. The study initiated with the work on relaxation of fiber optics of composition Ge-Se₃ Ge-Se₄ and Ge-Se₉ and their response to shear stress under LASER irradiation in the Urbach region. This leads to the determination of their viscosity under irradiation as a function of the power and wavelength used. This preliminary study enabled using this technique for optical tapering of chalcogenide fibers. A tapered fiber was obtained with good control over the diameter, and length of the sensor and improved sensing sensitivity was demonstrated. Finally, exploration of new glassy systems containing no chalcogenide elements but only heavy halide compounds (PbI₂, PbBr₂, CsI…) were investigated. These amorphous ionic compounds lead to infrared window transmitting from 500 nm up to 26 μm, unfortunately their moisture sensitivity as well as poor mechanical and thermal properties did not make them good candidate for sensor applications.
43
Chinnam, Rama Krishna Satish [Verfasser], and Aldo [Akademischer Betreuer] Boccaccini. "Functional Glasses and Glass-ceramics Derived from Industrial Waste / Chinnam Rama Krishna Satish. Gutachter: Aldo Boccaccini." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1054731667/34.
Full text
44
Malakho, Artem. "Second order optical nonlinearity in the crystals, glasses and glass-ceramic oxides containing vanadium and niobium." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13155.
Full textAbstract:
Les propriétés optiques nonlinéaires du deuxième ordre ont été induites par polarisation thermique dans des verres borophosphates ou borates de sodium et niobium. Les propriétés physico-chimiques et la recristallisation des verres ont été étudiées. Les valeurs des susceptibilités nonlinéaires d'ordre 2 ont été déterminées en fonction de la composition, des conditions de polarisation et du degré de cristallisation dans les verres. On observe notamment que la cristallisation de NaNbO3 dans des verres borates permet de gagner un ordre de grandeur. En parallèle, des matériaux cristallins vanadate de calcium et de bismuth ont été élaborés, leur susceptibilité non linéaire a été mesurée et corrélée à leurs structures et propriétés diélectriques.
45
Suh, Jin-Yoo Johnson W. L. Johnson W. L. "Fracture toughness study on bulk metallic glasses and novel joining method using bulk metallic glass solder /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-01062009-001830.
Full text
46
Parupudi, Aarti. "Singing wine glasses." Kansas State University, 2015. http://hdl.handle.net/2097/19706.
Full textAbstract:
Master of ScienceComputing and Information Sciences
Daniel A. Andresen
One among the many inventions of Benjamin Franklin is the Glass Armonica, a musical instrument whose sound source was a series of resonating glass vessels. However, the Irish musician Richard Pockrich is typically credited as the first to play an instrument composed of glass vessels, called the Glass Harp in 1741, by rubbing his fingers around the rims. In this project “Singing Wine Glasses”, the principle of Franklin’s glass armonica is demonstrated with a wine glass. One hand is used to hold the glass steady at the base. The rim of glass is gently pressed with a moistened finger of the other hand and drawn in a circle around. When the pressure and amount of moisture are just right, the slight friction between the finger and the rim of glass causes vibrations in the sides of the glass. At a particular frequency, called the resonant frequency, the sides of the glass will vibrate most easily. The resonant frequency of wine glasses is typically within the range of human hearing (20-20,000 Hz), so the resulting resonant vibration is heard as a tone. The glass starts to sing when the vibration gets the molecules moving at their natural frequency. The resonant frequency changes with the amount of water filled in the glass. This android application deals with virtual glasses that serve the purpose of wine glasses filled with different amounts of water. Swiping on the glass edges would produce music, as per Franklin’s principle. The users would be free to select the number of glasses they want to play, and the amount of water-level in each glass. This application would also come with an enhanced feature of sustaining a particular note until the finger is released from the glass.
47
Uhlenhaut, Dirk Ingmar. "Structure-property correlations in glassy Mg-Cu-Y, and corrosion resistance of novel Mg-Al-Ga glasses /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17941.
Full text
48
Klenell, Simon. "Frigger tactics." Thesis, Konstfack, Keramik & Glas, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-3350.
Full textAbstract:
My work centers around the fact that I am a glassblower working with glass objects within a glasstradition. My BFA project from 2009 entitled ”the bastards have landed” was my first attempt atmapping out what that ultimately meant to me as a practitioner in a contemporary craft context. Theresult of that project was a discovery of my making as a way of using tradition to tell stories aboutitself. My conclusion was that by using the traditional objects as symbols I had a channel throughwhich I could communicate. Glass is a material who´s domains are closely connected to a domesticand consumeristic environment. It is put in a position where we react to its appearance with ourbody memory while also carries different social and material values depending on its appearance.When entering the master program at Konstfack University of Art Craft and Design, my idea wasthat over the next coming two years my focus would lie in the exploration and research of thesemechanisms as well as my own position as a maker and practitioner within these mechanisms.Craft, design and making are subjects that are constantly being talked about and analyzed from anumber of perspectives. There are philosophers, sociologists, historians and art historians constantlynegotiating what the field of craft is dealing with. This is something that I over the years have foundas something quite disturbing in some cases. This leaves me in a situation where I am no longerdefining my own practice. And when I am to define my practice I always do it through the ideas ofpeople from ”outside” my own position. There are many good writers from variousdisciplines writing about craft and making that I have had great use of and input from but I feel thatthere is a big lack of craft practitioners who are defining their discipline from their own standpoint.This situation is to me a bit outdated.So as mentioned above I have entered the master program with an idea to find out how to deal withveiled subjects such as tacit knowledge and material culture in order to try to transform them into acommunicative body of knowledge. My work during the past three semesters have been spread outover a number of different projects dealing with these subjects both based on objects as well asforming a discussion together with my master group.The main cause in this thesis is as always in my case to shed light on and to formulate questionsand hopefully answers around my own practice and its related subjects.The main reason for this is that craft and making as a tool for knowledge production is a cloudedsubject but according to me it holds a lot of potential. Not only for understanding questions outsidethe field but also to unveil and strengthen the practice itself.
49
Stabler, Christina [Verfasser], Emanuel [Akademischer Betreuer] Ionescu, and Martin [Akademischer Betreuer] Heilmaier. "Mechanical and Thermal Properties of SiOC-based Glasses and Glass Ceramics / Christina Stabler ; Emanuel Ionescu, Martin Heilmaier." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1187444359/34.
Full text
50
Barker, Michael Francis. "Crystallization of lithium alumino-silicate glasses and the formation of photomachinable glass ceramics of controlled thermal expansion." Thesis, University of Sheffield, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362506.
Full text