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Journal articles on the topic 'Hydrated crystalline oxides'
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1
Gaponov, Yu A., L. G. Karakchiev, N. Z. Lyakhov, B. P. Tolochko, K. Ito, and Y. Amemiya. "Structure changes in the sol–gel systems of hydrated oxides." Journal of Synchrotron Radiation 5, no. 3 (May 1, 1998): 962–63. http://dx.doi.org/10.1107/s0909049597015677.
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Sols of hydrated aluminium oxide, hydrated zirconium oxide and their mixtures were investigated during the xerogel–amorphous-product–crystalline-product transition by SAXS using synchrotron radiation. In the different temperature regions certain changes in structure and morphology were observed. Some correlation between the characteristics of the initial sols and their mixtures (the size and shape of the pores) was observed. In the temperature region 298–1173 K the characteristics of the mixed sol are defined by the characteristics of the initial sols.
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Wang, Ruocun, Ching-Chang Chung, Yang Liu, Jacob L. Jones, and Veronica Augustyn. "Electrochemical Intercalation of Mg2+ into Anhydrous and Hydrated Crystalline Tungsten Oxides." Langmuir 33, no. 37 (July 27, 2017): 9314–23. http://dx.doi.org/10.1021/acs.langmuir.7b00705.
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Ferenc, Wieslawa, Agnieszka Walkóv-Dziewulska, and Janusz Chrusciel. "Spectral and thermal behaviors of rare earth element complexes with 3,5-dimethoxybenzoic acid." Journal of the Serbian Chemical Society 68, no. 10 (2003): 751–63. http://dx.doi.org/10.2298/jsc0310751f.
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The conditions for the formation of rare earth element 3,5-dimethytoxybenzoates were studied and their quantitative composition and solubilities in water at 293 K were determined. The complexes are anhydrous or hydrated salts and their solubilities are of the orders of 10-5 ? 10-4 mol dm-3. Their FTIR, FIR and X-ray spectra were recorded. The compounds were also characterized by thermogravimetric studies in air and nitrogen atmospheres and by magnetic measurements. All complexes are crystalline compounds. The carboxylate group in these complexes is a bidentate chelating ligand. On heating in air to 1173 K, the 3,5-dimethoxybenzoates of rare earth elements decompose in various ways. The hydrated complexes first dehydrate to form anhydrous salts which then decompose in air to the oxides of the respective metals while in nitrogen to mixtures of carbon and oxides of the respective metals. The complexes are more stable in air than in nitrogen.
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Ferenc, W., K. Czapla, J. Sarzynski, and A. Zwolinska. "Comparison of some properties of 2,3 – and 3,4 – dimethoxybenzoates of Cu(II), Co(II) and Nd(III)." Eclética Química Journal 33, no. 2 (February 5, 2018): 07. http://dx.doi.org/10.26850/1678-4618eqj.v33.2.2008.p07-12.
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The physicochemical properties of 2,4-, and 3,4-dimethoxybenzoates of Cu(II), Co(II) and Nd(III) were studied and compared to observe the -OCH3 substituent positions in benzene ring on the character of complexes. The analysed compounds are crystalline hydrated or anhydrous salts with colours depending on the kind of central ions: blue for Cu(II), pink for Co(II) and violet for Nd(III) complexes. The carboxylate groups bind as monodentate, bidentate bridging or chelating and even tridentate ligands. Their thermal stabilities were studied in air at 293-1173K. When heated the hydrated complexes release the water molecules and form anhydrous compounds which are then decomposed to the oxides of respective metals. Their magnetic moment values were determined in the range of 76-303K. The results reveal the compounds of Nd(III) and Co(II) to be the high-spin and that of Cu(II) forms dimer. The various positions of -OCH3 groups in benzene ring influence some of physicochemical properties of analysed compounds.
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Firsova, Olga A., Elena M. Filonenko, Yulia A. Lupitskaya, Hurshid N. Bozorov, and Anatoly V. Butakov. "Ion-exchange properties of solid solutions based on hydrated forms of monovalent metals antimonate-tungstates." Butlerov Communications 62, no. 6 (June 30, 2020): 74–79. http://dx.doi.org/10.37952/roi-jbc-01/20-62-6-74.
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The research of tungsten-antimony crystalline acid (TACA) structural transformations in the condition of ion-exchange and thermolysis of its substituted M+, H+-forms (M+ – Li, Na, K, Ag) were conducted. The data of thermogravimetric and qualitative X-ray phase analyses made it possible to conclude that the thermolysis of TACA and its derivatives proceeds in a wide temperature range from 300 to 1150 K being accompanied by the removal of crystalline water molecules with the formation of phases mixture containing complex antimony oxides of the ( -, - Sb2O4) modification and WO3. It was shown that compounds based on hydrated forms of monovalent metal antimonates-tungstates are stable up to 1023 K with a pyrochlore-type structure. For pyrochlore-like phases, a monotonic dependence of unit cell parameter a on ion-exchange degree α and the ionic radius of metals r was revealed indicating the formation of solid solutions Мх(Н3О)1–хWSbO6 nН2О (M+ – Li, Na, K, Ag; 0.0≤х<1.0; 0.0≤n<2.0) with a limited range of solubility from the crystal chemistry point of view. Within the framework of the Fd-3m space group, based on the data of X-ray diffraction analysis (Rietveld method), the structural characteristics of TACA and its substituted M+, H+-forms were refined, and a model for populating the corresponding metal ions by crystallographic positions of the pyrochlore-type structure was proposed. Using a complex of physicochemical methods (thermogravimetric, X-ray diffraction analyses and IR spectroscopy), a correlation between the composition of the obtained compounds, structural disorder, and ion-exchange properties were determined. According to the data of thermogravimetry and IR spectroscopy, it follows that the degree of compounds hydration analyzed depends on the nature of the alkaline ion. This allows to conclude that lithium and sodium ions are located in 16d– positions, dragging neutral water molecules into the structure occupying 8b-positions. In this case, potassium ions can partially occupy both 16d- and 8b-positions of the structure.
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Ferenc, Wieslawa, and Agnieszka Walków-Dziewulska. "Complexes of light lanthanides with 2,4-dimethoxybenzoic acid." Journal of the Serbian Chemical Society 65, no. 1 (2000): 27–35. http://dx.doi.org/10.2298/jsc0001027f.
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The complexes of light lanthanides with 2,4-dimethoxybenzoic acid of the formula: Ln(C9H9O4)3.nH2O where Ln = La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(IIII), and n = 3 for La(III), Gd(III), n = 2 for Sm(III), Eu(III), and n = 0 for Ce(III), Pr(III), Nd(III) have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric studies and X-ray diffraction measurements. The complexes have colours typical for Ln 3+ ions (La, Ce, Eu, Gd-white, Sm-cream, Pr-green, Nd-violet). The carboxylate group in these complexes is a symmetrical, bidentate, chelating ligand. They are crystalline compounds characterized by various symmetry. On heating in air to 1273 K the 2,4-dimethoxybenzoates of the light lanthanides decompose in various ways. The hydrated complexes decompose in two or three steps while those of anhydrous ones only in one or two. The trihydrate of lanthanum 2,4-dimethoxybenzoate first dehydrates to form the anhydrous salt, which then decomposes to La2O3 via the intermediate formation of La2O2CO3. The hydrates of Sm(III), Eu(III), Gd(III) decompose in two stages. First, they dehydrate forming the anhydrous salts, which then decompose directly to the oxides of the respective metals. The anhydrous complexes of Ce(III), Pr(III) decompose in one step, while that of Nd(III) in two. The solubilities of the 2,4-dimethoxybenzoates of the light lanthanides in water and ethanol at 293 K are in the order of: 10 -3 mol dm -3 and 10 -4.10 -3 mol dm-3, respectively.
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Jung, T. H., and R. V. Subramanian. "Alkali resistance enhancement of basalt fibers by hydrated zirconia films formed by the sol-gel process." Journal of Materials Research 9, no. 4 (April 1994): 1006–13. http://dx.doi.org/10.1557/jmr.1994.1006.
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Basalt fibers were dip-coated in zirconium-n-propoxide, unstabilized or stabilized by chelation with ethyl acetoacetate. The thermal transformations of the hydrated zirconia coatings formed were investigated by dynamic x-ray diffraction and differential thermal analysis. The changes in the surface chemical compositions of coated and uncoated fibers, following alkali immersion extending to 90 days, were characterized by EDXA and IR spectral analysis. Fiber strengths were also measured after immersion in 0.1 M NaOH for different durations. It was found that the transition of the amorphous zirconia coating to the tetragonal crystalline phase is shifted to higher temperatures by chelation of the zirconium alkoxide. Alkali corrosion of the uncoated basalt fibers results in dissolution of the oxides of Si, Al, and Ca, and the formation of unsoluble hydroxides of Fe, Mg, and Ti from the chemical constituents of basalt. These reactions are suppressed by the protective zirconia coating on basalt fibers formed by the unstabilized zirconium alkoxide. However, the coating formed from zirconium propoxide stabilized by ethyl acetoacetate does not form an effective barrier against alkali attack since it is easily detached from the fiber surface during alkali immersion. The tensile strength of uncoated basalt fibers is drastically reduced by alkali attack. But the strength of zirconia-coated basalt fibers is maintained even after 90 days of alkali immersion. The vastly improved alkaline durability of the coated fibers shows the potential of zirconia-coated basalt fibers for cement reinforcement.
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Mio, Matthew J., and Jeffrey S. Moore. "Supramolecular Aufbau: Folded Polymers as Building Blocks for Adaptive Organic Materials." MRS Bulletin 25, no. 4 (April 2000): 36–41. http://dx.doi.org/10.1557/mrs2000.27.
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The design of inorganic and organic solids with novel structures and properties has long been the object of materials research. The classical examples of porous materials (i.e., involving reversible guest passage) are zeolites. First discovered in the mid-1700s, zeolites are hydrated, crystalline aluminosilicates that organize into stable, discrete frameworks. Basic structures employ tetrahedral atoms (silicon or aluminum) bridged by oxygen atoms, where each oxygen is shared between two metalloid tetrahedra. Resulting covalent lattices can be neutral or negatively charged (as a result of bridging oxides) and often employ alkali metal or alkalineearth counterions. As a consequence of this ordered structure, zeolites both benefit from and are limited by their highly geometrical nature: their rigid structures are inherently robust, yet they are difficult to process. In addition, while natural and unnatural zeolites have been characterized, harsh synthetic conditions are common to both and lead to limitations in design and processability. Even so, these impediments have not prevented constructing a myriad of architectures on zeolite host lattices. Strengths and weaknesses aside, zeolites demonstrate a major objective of materials chemistry: the ability to manifest macroscopic physical properties based on embedded microscopic structure.
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Dercz, Grzegorz, Lucjan Pająk, Krystian Prusik, Roman Pielaszek, Janusz J. Malinowski, and Wojciech Pudło. "Structure Analysis of Nanocrystalline MgO Aerogel Prepared by Sol-Gel Method." Solid State Phenomena 130 (December 2007): 203–6. http://dx.doi.org/10.4028/www.scientific.net/ssp.130.203.
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Wet gel obtained by sol-gel technique was dried in supercritical CO2 to prepare hydrated form of magnesium oxide. Calcination at 723 K under vacuum yielded nanocrystalline MgO aerogel. Structure studies were performed by X-ray diffraction, scanning and transmission electron microcopies. Electron microscopy images reveal rough, unfolded and ramified structure of solid skeleton. Specific surface area SBET was equal to 238 m2/g. X-ray pattern reveals the broadened diffraction lines of periclase, the only crystalline form of magnesium oxide. The gamma crystallite size distribution was determined using FW 5 4 / 5 1 M method proposed by R. Pielaszek. The obtained values of <R> and σ (measure of polydispersity) of particle size parameters are equal to 6.5 nm and 1.8 nm, respectively, whereas the average crystallite size estimated by Williamson-Hall procedure was equal to 6.0 nm. The obtained at Rietveld refinement Rwp, and S fitting parameters equal to 6.62% and 1.77, respectively, seem to be satisfactory due to the nanosize of MgO crystallites and because of the presence of amorphous phase.
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Zhao, Qiang, X. F. Pang, Le Wei Liu, and Bo Deng. "The Biological Effect of Iron Oxide and Its Hydrate Nanoparticles." Solid State Phenomena 121-123 (March 2007): 735–38. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.735.
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Iron oxide and its hydrate nanoparticles were synthesized by hydrothermal method and confirmed by infrared and SEM (Scanning Electron Microscope) et al. The dimensions of the nanoparticles are about 50-120 nm. The crystalline form of iron oxide nanoparticles is like globosity while its hydrate rod. Amino acids intermingling with the synthesized nanoparticles were crystallized to investigate the space effect of the nanoparticles. The crystalline forms of crystal are different to that of pure amino acid. The positions and width of the nanoparticles’ peaks in the infrared spectrum are changed too. Microscope observation and infrared spectrum results indicated the nanoparticles had changed the internal structure of amino acids crystal. To considerate the toxicity of the synthesized nanoparticles, MTT (3-(4,5-dimethylthiazol 2-yl)-2,5 diphenyltetrazolium bromide) assay was used to determine their cytotoxicity. The OD value (Optical Density) was used to calculated RGR% (Relative Generation Rate) of cells, which determined the grade of cytotoxicity. The RGR of nanoparticles of iron oxide and its hydrate are about 1 to 2, which indicate they have just low toxicity.
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Allaf, Rula M., and Louisa J. Hope-Weeks. "Synthesis of ZnO-CuO Nanocomposite Aerogels by the Sol-Gel Route." Journal of Nanomaterials 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/491817.
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The epoxide addition sol-gel method has been utilized to synthesize porous zinc-copper composite aerogels in the zinc-to-copper molar ratios of 50 : 50 to 90 : 10. A two-step mixing approach has been employed to produce aerogels composed of nano- to micrometer sized particles. The aerogels were characterized by ultrahigh resolution scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. The as-synthesized aerogels had a thin flake- or petal-like microstructure comprised of clustered flakes on two size scales; they were identified as being crystalline with the crystalline species identified as copper nitrate hydroxide, zinc hydroxide chloride hydrate, and zinc hydroxide nitrate hydrate. Annealing of the aerogel materials at a relatively low temperature (400°C) resulted in a complete phase transition of the material to give highly crystalline ZnO-CuO aerogels; the aerogels consisted of networked nanoparticles in the ~25–550 nm size range with an average crystallite size of ~3 nm and average crystallinity of 98%. ZnO-CuO aerogels are of particular interest due to their particular catalytic and sensing properties. This work emphasizes the versatility of this sol-gel route in synthesizing aerogels; this method offers a possible route for the fabrication of aerogels of different metal oxides and their composites.
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Bartels, T., B. Eichler, P. Zimmermann, H. W. Gäggeler, and M. Ammann. "The adsorption of nitrogen oxides on crystalline ice." Atmospheric Chemistry and Physics Discussions 2, no. 2 (April 16, 2002): 431–68. http://dx.doi.org/10.5194/acpd-2-431-2002.
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Abstract. The partitioning of nitrogen oxides between ice and air is of importance to the ozone budget in the upper troposphere. In the present study, adsorption of nitrogen oxides on ice was investigated at atmospheric pressure using a chromatographic technique with radioactively labelled nitrogen oxides at low concentrations. The measured retentions solely depended on molecular adsorption and were not influenced by dimerisation, formation of encapsulated hydrates on the ice surface, dissociation of the acids, nor by migration into a quasi-liquid layer or grain boundaries. Based on the chromatographic retention and the model of thermo-chromatography, the standard adsorption enthalpy of -20 kJ mol-1 for NO, -22kJ mol-1 for NO2, -30kJ mol-1 for peroxyacetyl nitrate, -32kJ mol-1 for HON} and -44 kJ mol-1 for HNO3 was calculated. To perform those calculations within the model of thermo-chromatography, the standard adsorption entropy was calculated based on statistical thermodynamics. In this work, two different choices of standard states were applied, and consequently different values of the standard adsorption entropy, of either between -39 kJ mol-1 and -45kJ mol-1, or -164 kJ mol-1 and -169 kJ mol-1 for each nitrogen oxide were derived. The standard adsorption enthalpy was identical for both standard adsorption entropies and thus shown to be independent of the choice of standard state. A brief outlook on environmental implications of our findings indicates that adsorption on ice might be an important removal process of HNO3. In addition, it might be of some importance for HONO and peroxyacetyl nitrate and irrelevant for NO and NO2.
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Bartels, T., B. Eichler, P. Zimmermann, H. W. Gäggeler, and M. Ammann. "The adsorption of nitrogen oxides on crystalline ice." Atmospheric Chemistry and Physics 2, no. 3 (September 20, 2002): 235–47. http://dx.doi.org/10.5194/acp-2-235-2002.
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Abstract. The partitioning of nitrogen oxides between ice and air is of importance to the ozone budget in the upper troposphere. In the present study, adsorption of nitrogen oxides on ice was investigated at atmospheric pressure using a chromatographic technique with radioactively labelled nitrogen oxides at low concentrations. The measured retentions solely depended on molecular adsorption and were not influenced by dimerisation, formation of encapsulated hydrates on the ice surface, dissociation of the acids, nor by migration into a quasi-liquid layer or grain boundaries. Based on the chromatographic retention and the model of thermo-chromatography, the standard adsorption enthalpy of -20 kJ mol-1 for NO, -22kJ mol-1 for NO2, -30kJ mol-1 for peroxyacetyl nitrate, -32kJ mol-1 for HON} and -44 kJ mol-1 for HNO3 was calculated. To perform those calculations within the model of thermo-chromatography, the standard adsorption entropy was calculated based on statistical thermodynamics. In this work, two different choices of standard states were applied, and consequently different values of the standard adsorption entropy, of either between -39 kJ mol-1 and -45kJ mol-1, or -164 kJ mol-1 and -169 kJ mol-1 for each nitrogen oxide were derived. The standard adsorption enthalpy was identical for both standard adsorption entropies and thus shown to be independent of the choice of standard state. A brief outlook on environmental implications of our findings indicates that adsorption on ice might be an important removal process of HNO3. In addition, it might be of some importance for HONO and peroxyacetyl nitrate and irrelevant for NO and NO2.
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Cuesta, Ana, Ángeles G. De la Torre, Isabel Santacruz, Ana Diaz, Pavel Trtik, Mirko Holler, Barbara Lothenbach, and Miguel A. G. Aranda. "Quantitative disentanglement of nanocrystalline phases in cement pastes by synchrotron ptychographic X-ray tomography." IUCrJ 6, no. 3 (April 27, 2019): 473–91. http://dx.doi.org/10.1107/s2052252519003774.
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Mortars and concretes are ubiquitous materials with very complex hierarchical microstructures. To fully understand their main properties and to decrease their CO2 footprint, a sound description of their spatially resolved mineralogy is necessary. Developing this knowledge is very challenging as about half of the volume of hydrated cement is a nanocrystalline component, calcium silicate hydrate (C-S-H) gel. Furthermore, other poorly crystalline phases (e.g. iron siliceous hydrogarnet or silica oxide) may coexist, which are even more difficult to characterize. Traditional spatially resolved techniques such as electron microscopy involve complex sample preparation steps that often lead to artefacts (e.g. dehydration and microstructural changes). Here, synchrotron ptychographic tomography has been used to obtain spatially resolved information on three unaltered representative samples: neat Portland paste, Portland–calcite and Portland–fly-ash blend pastes with a spatial resolution below 100 nm in samples with a volume of up to 5 × 104 µm3. For the neat Portland paste, the ptychotomographic study gave densities of 2.11 and 2.52 g cm−3 and a content of 41.1 and 6.4 vol% for nanocrystalline C-S-H gel and poorly crystalline iron siliceous hydrogarnet, respectively. Furthermore, the spatially resolved volumetric mass-density information has allowed characterization of inner-product and outer-product C-S-H gels. The average density of the inner-product C-S-H is smaller than that of the outer product and its variability is larger. Full characterization of the pastes, including segmentation of the different components, is reported and the contents are compared with the results obtained by thermodynamic modelling.
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Xiao, Zhen Hui, Shui Sheng Wu, Yan Lin Sun, Yu Lin Zhao, and Ya Ming Wang. "Microwave-Hydrothermal Synthesis and Characterization of Graphene." Advanced Materials Research 602-604 (December 2012): 917–20. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.917.
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Graphene was synthesized by microwave-hydrothermal chemical reduction of graphite oxide using hydrazine hydrate as the reducing agent. Graphene was characterized using X-ray diffraction, UV-visible spectrum, FT-IR spectrum and scanning electron microscopy. Results indicated that the as-prepared graphene was wrinkled and comprised fewer graphenes with a highly crystalline structure.
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Johnsen, Rune E., Alfons M. Molenbroek, and Kenny Ståhl. "XRPD/TEM studies of model high-temperature shift catalysts." Journal of Applied Crystallography 39, no. 4 (July 15, 2006): 519–26. http://dx.doi.org/10.1107/s0021889806016116.
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The combination of transmission electron microscopy (TEM) andin situX-ray powder diffraction (XRPD) for the investigation of four model high-temperature shift catalysts makes it possible to obtain and compare information concerning the crystallite and particle shapes and sizes before, during and after the reduction of the synthesized hematite-based model catalyst to the active magnetite-based catalyst. Two chromium-containing iron oxide model catalysts and two pure iron oxide model catalysts were synthesized from hydrated chloride or nitrate salts, resulting in particles with different shapes and sizes. The average crystallite sizes of four model catalysts were determined by XRPD using the Scherrer equation before and after the reduction. The crystallite sizes determined before the reduction were compared with particles sizes determined from TEM images of the same samples. These sizes were generally in good agreement. By using the Rietveld method combined with the Scherrer equation and the Lorentzian Scherrer broadening parameters, the development of the average crystallite size during thein situreduction was demonstrated. This showed that the average crystallite size of the remaining hematite increases when the reduction begins. Additionally, the average crystallite sizes of the reduced samples showed that the chromium-containing model catalysts have the smallest increase in the overall crystallite size.
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Jadhav, Sarika Vishvnbath, and Limbraj Sopan Ravangave. "Influence of zinc ion concentration on structure, morphology and optical properties of spray deposited ZnO thin films." International Journal of Advances in Applied Sciences 10, no. 3 (September 1, 2021): 198. http://dx.doi.org/10.11591/ijaas.v10.i3.pp198-204.
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<p>Zinc Oxide (ZnO) thin films were deposited for five different molarity (M) of Zinc acetate hydrated (0.075, 0.1, 0.125, 0.15, 0.175 M) using simple spray technique to study the effect of zinc ion concentration on structure, morphology and optical properties. The XRD patterns of deposited ZnO thin films show hexagonal crystal structure with wurtzite symmetry. The effect of molarity on morphology was studied using scanning electron microscopy (SEM). The elemental analysis was studied by using energy dispersive X-ray analysis (EDX). The optical absorption was recorded by using systronics double beam spectrophotometer (2201). Crystallite size estimated from XRD data was in nanometre (nm) range; however, films deposited for 0.15 M zinc acetate show maximum crystallite size (66 nm) as compared to other samples. All the films show low absorption in wide range (340-999 nm) of electromagnetic spectrum. However, ZnO film deposited for 0.15 zinc acetate hydrated shows maximum blue shifting of absorption edge and higher band gap (3.8 eV) as compared to other samples.</p>
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Kotsyubynsky, V., A. Hrubiak, L. Mohnatska, M. Gasyuk, and V. Moklyak. "The Effect of Precursors Concentration on the Structure and Micromagnetic Properties of Ultrafine Iron Oxides Obtained by Sol-Gel Route." Journal of Vasyl Stefanyk Precarpathian National University 3, no. 1 (July 7, 2016): 38–45. http://dx.doi.org/10.15330/jpnu.3.1.38-45.
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Nanodispersed composite materials -Fe2O3/-Fe2O3 were obtained by thermaldecomposition of iron citrate xerogel hydrate synthesized by iron nitrate and citrate acid solutionswith different colloidal solutions of Fe(NO3)39H2O and С6Н8О7 Н2О for different molar ratiobetween precursors. The influence of the precursors molar concentration and calcinationtemperature on the material phase composition, crystalline and magnetic microstructure, surfacecondition was studied. Methods of X-ray diffraction, Mössbauer spectroscopy, electron microscopyand IR - spectroscopy were used.
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Amadelli, Rossano, Luca Samiolo, and Aleksandr Velichenko. "An electrochemical and radiotracer investigation on lead dioxide: Influence of deposition current and temperature." Journal of the Serbian Chemical Society 78, no. 12 (2013): 2099–114. http://dx.doi.org/10.2298/jsc131022122a.
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The properties of electrodeposited PbO2 are sensibly influenced by deposition current and temperature. In particular, tritium radiotracer measurements have demonstrated that protons are incorporated in the bulk of the oxide film and on its surface. The degree of hydration increases with increasing current and decreases with temperature, and is related to the morphological characteristics of the oxide such as roughness measured by changes of the double layer capacity. Conversely, the amount of hydrogen has negligible effects on the number of free carriers evaluated from Mott-Schottky plots. The hydration degree of the surface seems to be an important factor influencing electrocatalytic processes at high potentials such as O2 evolution and O3 formation. On less hydrated, more crystalline PbO2 surfaces the first process is inhibited, and accordingly, the second is favored.
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Behera, M., and G. Giri. "Green synthesis and characterization of cuprous oxide nanoparticles in presence of a bio-surfactant." Materials Science-Poland 32, no. 4 (December 1, 2014): 702–8. http://dx.doi.org/10.2478/s13536-014-0255-4.
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AbstractHerein, we report a facile green synthesis of Cu2O nanoparticles (NPs) using copper sulfate as precursor salt and hydrazine hydrate as reducing agent in presence of bio-surfactant (i.e. leaves extract of arka — a perennial shrub) at 60 to 70 °C in an aqueous medium. A broad band centered at 460 nm in absorption spectrum reveals the formation of surfactant stabilized Cu2O NPs. X-ray diffraction pattern of the surfactant stabilized NPs suggests the formation of only Cu2O phase in assistance of a bio-surfactant with the crystallite size of ∼8 nm. A negative zeta potential of −12 mV at 8.0 pH in surfactant stabilized Cu2O NPs hints non-bonding electron transfer from O-atom of saponin to the surface of NP. Red-shift in the vibrational band (Cu-O stretching) of Cu2O from 637 cm−1 to 640 cm−1 in presence of bio-surfactant suggests an interfacial interaction between NPs and O-atoms of -OH groups of saponin present in the plant (i.e. Calotropis gigantean) extract. From X-ray photoelectron spectroscopy spectra, a decrease in binding energy of both 2p3/2 and 2p1/2 bands in Cu2O with saponin molecules as compared to bulk Cu atom reveals a charge transfer interaction between NP and saponin surfactant molecules. Transmission electron microscopy images show crystalline nature of Cu2O NPs with an fcc lattice.
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Hu, Rong, Huasheng Wu, and Kunquan Hong. "Synthesis and characterization of nanocrystalline tungsten oxide nanosheets in large scale." Journal of Materials Research 24, no. 1 (January 2009): 187–91. http://dx.doi.org/10.1557/jmr.2009.0026.
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A high quantity of tungsten oxide nanosheets were synthesized by oxidizing tungsten plates with potassium hydrate as the catalyst and tungsten plate as the substrate. The structural and geometrical properties were characterized by various techniques. It was found that the crystalline nanosheets have a WO3 structure with thicknesses of 30–50 nm and widths up to tens of micrometers. There exist two characteristic acute angles of about 37° or 51° on the nanosheet plane. The formation of these angles and the growth mechanism were discussed.
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Priscilla, S. Janet, V. Andria Judi, R. Daniel, and K. Sivaji. "Effects of Chromium Doping on the Electrical Properties of ZnO Nanoparticles." Emerging Science Journal 4, no. 2 (April 1, 2020): 82–88. http://dx.doi.org/10.28991/esj-2020-01212.
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Nanostructured ZnO has gained a considerable amount of attention due to its unique physical and chemical properties and due to its remarkable performance in the fields of optics, photonics and electronics. The scope of this work is to study the Structural, Optical and Electronic properties of Pure Zinc Oxide (ZnO) and Chromium doped Zinc Oxide nanoparticles. These nanoparticles were synthesized by low-temperature precipitation method at various concentrations in the range (Zn1-xCrxO; (x = 0, 0.1& 0.3)). The precursors used were analytical grade Zinc Nitrate Hexahydrate and Chromium Nitrate Nona hydrate. The synthesized nanoparticles were annealed at 400°C. The Structural property of the synthesized nanoparticles was analysed by XRD (X-Ray diffraction) and was confirmed to exhibit a crystalline hexagonal wurtzite structure with an average crystallite size of 55nm. The functional groups were analysed using FTIR (Fourier Transformed Infra-red spectroscopy). The Morphology was analysed by FESEM (Field Emission Scanning Electron Microscope) and a change in morphology from spherical to spindle like structure was observed. The Optical properties were analysed using UV-Vis spectroscopy, the absorption spectrum for electromagnetic spectrum was observed and the changes in the optical band gap of ZnO nanoparticles with Chromium dopant addition were calculated to be in the range of 3.6 eV. The Electrical property of the synthesised nanoparticles was analysed using Electrochemical Impedance Spectroscopy (EIS) and the conductivity was calculated to be in the range of 1.1e-07S/m.
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Silatikunsatid, Treerat, Nittaya Jaitanong, and Suparut Narksitipan. "A Study on Influence of Zinc Oxide in Cement Composite Materials." Key Engineering Materials 772 (July 2018): 95–99. http://dx.doi.org/10.4028/www.scientific.net/kem.772.95.
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In this research, the influence of zinc oxide (ZnO) on the phase compositions and crystalline structure and microstructure of cement composite was studied. ZnO powder (0.5-1 wt% of cement) was used as an additive material. The Portland cement and ZnO powder were blended and mixed with water at the ratio constant (W/C) of 0.4. Then, the paste was cast into the molded for 24 hours. After these periods, the samples were dried at temperature 50°C for 24 hours. Those of samples were analyzed of crystalline structure and phase compositions by using X-ray diffraction technique (XRD). Microstructure analysis by using field emission scanning electron microscopy (SEM). It was found that the XRD spectra showed phases of calcium hydroxide (CH) and calcium silicate hydrated (CS), which were hydration products of cementitious material. Moreover, phase of zinc hydroxide (Zn(OH)2) is detected. Zn(OH)2have affected on the retardation of hydration reaction (more than 48 h). Zn(OH)2phase was formed on the surface of anhydrous tricalcium silicate (C3S) main compound in cement. The intensity of un-hydration products (C3S and C2S) increased with increasing content of ZnO nanoparticle in cement composites.
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Udomsap, Parncheewa, and Boonyawan Yoosuk. "Influences of Water on the Hydration of Calcined Natural Calcite: Properties and Transesterification Activity Improvement." Advanced Materials Research 93-94 (January 2010): 75–78. http://dx.doi.org/10.4028/www.scientific.net/amr.93-94.75.
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This paper presents the technique that can considerably improve basicity and transesterification activity of calcined natural calcite. Calcined calcite was refluxed in water followed by the calcinations at 600 oC. The characterization results indicate that this procedure substantially increases both the specific surface area and the amount of basic site. Hydration and subsequent calcination also generates a new calcium oxide with less crystalline. ME content was enhanced to 93.9 wt% in 1 hr from 75.5 wt% of calcined calcite. The results imply that the active sites produced by the calination of hydrated sample at 600 oC have higher basicity than those generated from calcinations of fresh calcite at 800 oC. The present study provides new insights for improving catalyst activity by tailoring the preparation conditions.
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Li, Ji-Guang, Takayasu Ikegami, Toshiyuki Mori, and Yoshiyuki Yajima. "Monodispersed Sc2O3 precursor particles via homogeneous precipitation: Synthesis, thermal decomposition, and the effects of supporting anions on powder properties." Journal of Materials Research 18, no. 5 (May 2003): 1149–56. http://dx.doi.org/10.1557/jmr.2003.0157.
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Monodispersed Sc2O3 precursor particles were synthesized by the urea-based homogeneous precipitation method, with an investigation into the effects of supporting anions (NO3−, Cl−, and SO4 2−) on powder properties. Characterizations of the powders were achieved by elemental analysis, x-ray diffractometry, Fourier transform infrared, differential thermal analysis/thermogravimetry, high-resolution scanning electron microscopy, and the Brunauer-Emmett-Teller method. Unlike other rare earths, Sc3+ does not precipitate as basic carbonate but instead forms hydrated γ-ScOOH from either nitrate or chloride solution. Particles of the hydrated γ-ScOOH are pumpkin-shaped (approximately 1.0 μm) and are made up of thin-platelike crystallites emanating from a common axis. The presence of complexing SO42− changes the reaction chemistry toward Sc2O3 powders, leading to basic sulfate [Sc(OH)1.6(SO4)0.7 η H2O] precursor particles having hexagonal morphology (approximately 10 μm in diameter and 0.5 μm in thickness). The hydrated γ-ScOOH directly converts to Sc2O3 by calcination at 400 °C or above, while the basic sulfate transforms to oxide at temperatures ≥ 900 °C via an amorphous state and a Sc2(SO4)3 intermediate. The effect of SO42− on powder morphologies and reaction chemistry is discussed. Nanocrystalline Sc2O3 powders comprising monodispersed particles were obtained via thermal decomposition of the precursors.
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Krishnan, Saravanan Vanal, Sivakumar Palanivelu, Muthu Manickam Muthukaruppan Ambalam, Ragavendran Venkatesan, Muthukumar Arivalagan, Joshua M. Pearce, and Jeyanthinath Mayandi. "Chemical Synthesis and Characterization of Nano Alumina, Nano Composite of Carbon–Alumina and Their Comparative Studies." Zeitschrift für Physikalische Chemie 232, no. 12 (November 27, 2018): 1827–42. http://dx.doi.org/10.1515/zpch-2017-1075.
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Abstract Aluminium oxide (Al2O3) nano particles were synthesized by using both the sol gel technique and solid state reaction (SSR) method. Different proportion of nano carbon cones from 0.5% to 3.5% is doped with aluminium nitrate nano hydrate and annealed subsequently at 1000°C for 3 h to synthesize the nano composite of carbon–alumina. The synthesized samples were characterized by X-ray diffraction to identify the presence of different phases and transitions during this process. The average crystallite size of the nano alumina is found to be 45 nm by sol gel and 43 nm by SSR method respectively by Debye–Scherrer method. Average crystallite size and lattice strain of nano alumina are also estimated from Williamson Hall (WH) plot analysis. It is found to be 69 nm with the strain of 3.3×10−3 in sol gel, and in SSR method, it is 72 nm with the strain is 3.9×10−3. The interplanar distance of various planes of alumina are estimated and compared with JCPDS values. Similar analysis has also been extended for the nano composite of carbon–alumina. The surface morphology of the samples are analyzed using scanning electron microscopy and rough estimate of the crystallites is also given. From the Raman analysis, the presence of alpha phase of alumina has been confirmed. The presence of carbon in the composite has been established through diffuse reflectance spectroscopy. The FTIR spectra of the composite samples ensured the presence of Al–O–Al, O–H and C=O bonds.
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Murray, B. J., A. E. Haddrell, S. Peppe, J. F. Davies, J. P. Reid, D. O'Sullivan, H. C. Price, et al. "Glass formation and unusual hygroscopic growth of iodic acid solution droplets with relevance for iodine oxide particles in the coastal marine boundary layer." Atmospheric Chemistry and Physics Discussions 12, no. 3 (March 20, 2012): 7879–908. http://dx.doi.org/10.5194/acpd-12-7879-2012.
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Abstract. Iodine oxide particles are known to nucleate in the marine boundary layer where gas phase molecular iodine and organoiodine species are produced by macroalgae. There has been some debate over the chemical identity of these particles. Hygroscopic measurements have been used to infer that they are composed of insoluble I2O4, while elemental analysis of laboratory generated particles suggests soluble I2O5 or its hydrated form iodic acid, HIO3 (I2O5 · H2O). In this paper we explore the response of super-micron sized aqueous iodic acid solution droplets to varying humidity using both Raman microscopy and single particle electrodynamic traps. These measurements reveal that the propensity of an iodic acid solution droplet to crystallise is negligible on drying to ~0% relative humidity (RH). On applying mechanical pressure to these droplets they shatter in a manner consistent with an ultra-viscous liquid or a brittle glass, but subsequent water uptake between 10 and 20% RH causes their viscosity to reduce sufficiently that the cracked droplets flow and merge. The persistence of iodic acid solution in an amorphous state, rather than a crystalline state, suggests they will more readily accommodate other condensable material and are therefore more likely to grow to sizes where they may serve as cloud condensation nuclei. On increasing the humidity to ~90% the mass of the droplets only increases by ~20% with a corresponding increase in radius of only ~6 %, which is remarkably small for a highly soluble material. We suggest that the small growth factor of aqueous iodic acid solution droplets is consistent with the small aerosol growth factors observed in field experiments.
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Mädler, L., W. J. Stark, and S. E. Pratsinis. "Simultaneous deposition of Au nanoparticles during flame synthesis of TiO2 and SiO2." Journal of Materials Research 18, no. 1 (January 2003): 115–20. http://dx.doi.org/10.1557/jmr.2003.0017.
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Nanostructured gold/titania and gold/silica particles with up to 4 wt% Au were made by a single-step process in a spray flame reactor. Gold(III)-chloride hydrate and titania- or silica-based metalorganic precursors were mixed in a liquid fuel solution, keeping concentrations in the flame and overall combustion enthalpy constant. The powders were characterized by x-ray diffraction, transmission electron microscopy, Brunauer–Emmett–Teller, and ultraviolet–visible analysis. The titania or silica specific surface area and the crystalline structure of titania were not affected by the presence of gold in the flame. Furthermore the size of the gold deposits was independent of the metal oxide support (TiO2 or SiO2) and its specific surface area (100 and 320 m2/g, respectively). The gold nanoparticles were nonagglomerated, spherical, mostly single crystalline, and well dispersed on the metal oxide support. Depending on the Au weight fraction (1, 2, and 4 wt%) the Au nanoparticles' mass mean diameter was 3, 7, and 15 nm, respectively, on both titania and silica. The particles showed surface plasmon absorption bands in the ultraviolet–visible region, which is typical for nano-sized gold. This absorption band was red shifted in the case of the titania support, while no shift occurred with the silica support.
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Kostura, Bruno, František Kovanda, Marta Valášková, and Juraj Leško. "Rehydration of Calcined Mg-Al Hydrotalcite in Acidified Chloride-Containing Aqueous Solution." Collection of Czechoslovak Chemical Communications 72, no. 9 (2007): 1284–94. http://dx.doi.org/10.1135/cccc20071284.
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The rehydration of periclase-like Mg-Al mixed oxide obtained by calcination of hydrotalcite- like precursor with a Mg/Al molar ratio of 2 was carried out in KCl-HCl solutions at various pH and constant concentration of Cl-. A buffer equilibrium accompanied by leaching out of Mg2+ cations from the solid was observed during rehydration, when reconstruction of the layered hydrotalcite structure takes place. With increasing HCl concentration in the rehydration solution, the Mg/Al molar ratio in the obtained solid gradually decreased from about 1.5 to 0.3. An anomaly was found, when the increasing concentration of acid resulted in increasing pH of final solution. The XRD measurements showed that the initially formed hydroxide form of hydrotalcite is transformed into randomly interstratified forms of the Mg-Al hydroxide hydrate/Mg-Al chloride hydroxide hydrate, which are accompanied by the release of OH- anions into solution. The crystalline structure of rehydrated product decreased as Mg2+ cations were released into solution, which was accompanied by incorporation of Cl- into the solid.
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Grzmil, Barbara, Marta Gleń, Bogumił Kic, and K. Lubkowski. "Study of the anatase to rutile transformation kinetics of the modified TiO2." Polish Journal of Chemical Technology 15, no. 2 (July 1, 2013): 73–80. http://dx.doi.org/10.2478/pjct-2013-0026.
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TiO2 attracts much interest because of its many potential applications. The use of titanium dioxide strongly depends on its polymorphic form: brookite, anatase, or rutile. Only rutile and anatase play an important role in industry. Anatase as a metastable form undergoes a non-reversible transformation into rutile. Understanding the kinetics of phase transformation and the processes of crystal growth of a material is essential for controlling its structure and, thus, its specific properties. The main purpose of this paper is to explain the anatase to rutile recrystallization kinetics in the modified TiO2 calcined from industrial hydrated titanium dioxide. The apparent activation energy of anatase to rutile transformation and the average size of titanium dioxide crystallites were determined for the unmodified TiO2 and TiO2 modified with P, K, Al, B, Zn, Zr, Ce, Sn, or Sb introduced in the amount of 0.5 mol% and 1.0 mol% when recalculated for their oxides. The growth of TiO2 crystallites during calcination was strongly inhibited by P, Ce and Zr, and inhibited to a lesser degree by Al, Sn and Sb. B and Zn did not affect the investigated process and K accelerated crystallites growth. The values of apparent activation energy depending on a modifier formed a relationship: Al<Sb<Sn<P<B<Ce<0=Zn=K<Zr. The observed dependencies can be explained by reactions occurring between the modifiers and titanium dioxide.
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Tan, Yan Ni, Liu Yong, Xiang He, Wen Wang, Dong Duan, Kai Yang Li, Hui Xia Li, and Lan Lan Luo. "PGA Fiber Reinforced Calcium Aluminate Cement for Orthopaedic Application." Materials Science Forum 852 (April 2016): 1188–93. http://dx.doi.org/10.4028/www.scientific.net/msf.852.1188.
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Calcium aluminate cement (CAC) is a penitential candidate for bone replacements with good bioactivity but relative lower strength. In this study, biodegradable PGA fiber was incorporated into the CAC paste in order to improve the strength of the material. And MC3T3 cells were seeded on the surface of CAC and CAC/fiber to study their in vitro biocompatibility. The results indicate that the PGA fiber can improve the compressive strength of CAC without changing the crystalline phases and micromorphology. Calcium aluminate oxide hydrate, katoite and Gibbsite crystals were detected by XRD. Plate-like crystals can be observed under FESEM. The MC3T3 cells were attached well on both CAC and CAC/fiber composite, indicating their good in vitro biocompatibility. In summary, fiber reinforcement can be an effective way to improve the properties of calcium aluminate cement for orthopaedic application.
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Butto, Nicole, Nicole Cotrina Vera, Felipe Díaz-Soler, Mehrdad Yazdani-Pedram, and Andrónico Neira-Carrillo. "Effect of Chitosan Electrospun Fiber Mesh as Template on the Crystallization of Calcium Oxalate." Crystals 10, no. 6 (May 31, 2020): 453. http://dx.doi.org/10.3390/cryst10060453.
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Biominerals fulfill various physiological functions in living organisms, however, pathological mineralization can also occur generating mineral pathologies such as the formation of calcium oxalate (CaOx) calculi in the urinary tract. Inspired by the ability of living organisms to generate biogenic minerals using biological organic matrices, and the need to understand the mechanisms of crystallization, three-dimensional fibrillary meshes based on chitosan fibers with random and controlled topology by electrospinning were manufactured. Chitosan was selected due to its active role on in vitro crystallization and its physicochemical properties, which allows the exposure of their functional chemical groups that could selectively stabilize hydrated crystalline forms of CaOx. CaOx crystals were generated on conductive tin indium oxide (ITO) glass substrates modified with electrospun chitosan fibers by using electrocrystallization (EC) technique. The chitosan fibers and the resulting CaOx crystals were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques, which demonstrated that the chemical nature and topology of the three-dimensional fibers used as organic template are key factors in the control of type, morphology, and crystallographic orientation of CaOx.
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Hedrich, Carina, Stefanie Haugg, Leutrim Pacarizi, Kaline P. Furlan, Robert H. Blick, and Robert Zierold. "Low-Temperature Vapor-Solid Growth of ZnO Nanowhiskers for Electron Field Emission." Coatings 9, no. 11 (October 25, 2019): 698. http://dx.doi.org/10.3390/coatings9110698.
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One-dimensional zinc oxide nanostructures have aroused interest from scientists and engineers for electron field emission applications because of their experimentally accessible high aspect ratio in combination with their low work function. A comprehensive study of the vapor-solid growth of zinc oxide (ZnO) nanowhiskers by utilizing zinc acetylacetonate hydrate and oxygen at low temperature (580 °C) is reported herein. The nanowhiskers morphology was investigated by varying different growth parameters, such as temperature, substrate type and position, gas flow, precursor amount, and growth time. According to the obtained parameter dependences, the process was optimized to achieve homogenous crystalline nanowhiskers with high aspect ratios and clearly defined surface facets and tips. We show electron field emission measurements from tailor-made ZnO nanowhiskers grown on n-doped silicon, titanium thin films, and free-standing silicon nitride membranes, revealing field emission turn-on fields significantly lower compared to a perfect flat ZnO thin film. Especially the latter devices—ZnO nanowhiskers on a free-standing membrane—might pave the way into a novel nanomembrane detector unit in proteomics, which can significantly extend the mass range of current time-of-flight mass spectrometers.
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Asab, Goshu, Enyew Amare Zereffa, and Teshome Abdo Seghne. "Synthesis of Silica-Coated Fe3O4 Nanoparticles by Microemulsion Method: Characterization and Evaluation of Antimicrobial Activity." International Journal of Biomaterials 2020 (March 31, 2020): 1–11. http://dx.doi.org/10.1155/2020/4783612.
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Magnetite and silica-coated magnetite (Fe3O4) nanoparticles (NPs) were synthesized by water-in-oil (W/O) microemulsion method from hydrated ferric nitrate, ferrous sulfate precursors and ammonia a precipitating agent with the assistance of Tween-80 and SDS surfactants. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, thermal analyzer, and infrared spectroscopy. X-ray diffraction pattern of Fe3O4 showed that particles were phase pure with a cubic inverse spinel structure and FT-infrared spectra confirmed the presence of Fe-O bond in tetrahedral and octahedral interstitial sites. The crystallite size determined from powder XRD data with Scherer’s equation was in the range of 7.3 ± 0.05 nm–10.83 ± 0.02 nm for uncoated Fe3O4 and 16 ± 0.14 nm for silica-coated Fe3O4 NPs. The SEM micrographs of the uncoated Fe3O4 oxide revealed the agglomeration of the magnetite (Fe3O4) particles. But the silica-coated Fe3O4 oxide exhibited homogeneous distribution of particles with relatively less agglomerate of the particles. The particle size of Fe3O4 NPs slightly increased with the temperature and precursor concentration. The antimicrobial activities of Fe3O4 and silica-coated Fe3O4 nanoparticles were tested against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Both Fe3O4 and silica-coated Fe3O4 NPs demonstrated better antimicrobial activities.
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Murray, B. J., A. E. Haddrell, S. Peppe, J. F. Davies, J. P. Reid, D. O'Sullivan, H. C. Price, et al. "Glass formation and unusual hygroscopic growth of iodic acid solution droplets with relevance for iodine mediated particle formation in the marine boundary layer." Atmospheric Chemistry and Physics 12, no. 18 (September 25, 2012): 8575–87. http://dx.doi.org/10.5194/acp-12-8575-2012.
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Abstract. Iodine oxide particles are known to nucleate in the marine boundary layer where gas phase molecular iodine and organoiodine species are produced by macroalgae. These ultra-fine particles may then grow through the condensation of other materials to sizes where they may serve as cloud condensation nuclei. There has been some debate over the chemical identity of the initially nucleated particles. In laboratory simulations, hygroscopic measurements have been used to infer that they are composed of insoluble I2O4, while elemental analysis of laboratory generated particles suggests soluble I2O5 or its hydrated form iodic acid, HIO3 (I2O5·H2O). In this paper we explore the response of super-micron sized aqueous iodic acid solution droplets to varying humidity using both Raman microscopy and single particle electrodynamic traps. These measurements reveal that the propensity of an iodic acid solution droplet to crystallise is negligible on drying to ~0% relative humidity (RH). On applying mechanical pressure to these droplets they shatter in a manner consistent with an ultra-viscous liquid or a brittle glass. Water retention in amorphous material at low RH is important for understanding the hygroscopic growth of aerosol particles and uptake of other condensable material. Subsequent water uptake between 10 and 20% RH causes their viscosity to reduce sufficiently that the cracked droplets flow and merge. The persistence of iodic acid solution in an amorphous state, rather than a crystalline state, suggests they will more readily accommodate other condensable material and are therefore more likely to grow to sizes where they may serve as cloud condensation nuclei. On increasing the humidity to ~90% the mass of the droplets only increases by ~20% with a corresponding increase in radius of only 6%, which is remarkably small for a highly soluble material. We suggest that the small growth factor of aqueous iodic acid solution droplets is consistent with the small aerosol growth factors observed in previous experiments.
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Barnes, N., S. J. Kitchin, and J. A. Hriljac. "Progress in the Intercalation of Pyridine and Other Organic Bases into Crystalline Bismuth Molybdenum Oxide Hydrate, BiMo2O7OH·2H2O." Inorganic Chemistry 38, no. 26 (December 1999): 6317–19. http://dx.doi.org/10.1021/ic9905502.
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Vlachou, Marilena, Natassa Pippa, Angeliki Siamidi, and Aimilia Kyrili. "Thermal analysis studies on the compatibility of furosemide with solid state and liquid crystalline excipients." Chemical Industry 74, no. 1 (2020): 15–23. http://dx.doi.org/10.2298/hemind190910002v.
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In the context of the present study, the thermal behavior of furosemide and the solid state excipients, sodium alginate, poly(ethylene oxide), poly(vinylpyrrolidone), lactose mono-hydrate and magnesium stearate, using Differential Scanning Calorimetry (DSC), was probed. It was found that the thermal behavior of these solid-state pharmaceutical excipients and furosemide correlates nicely with the literature relevant data. Regarding the furosemide-excipients mixtures, the DSC scans appear as a compilation of the thermal curves of each excipient. This suggests that the formulations containing these mixtures, may retain their stability over time. This information, which arises from the cooperativity of materials, their thermal stability and behavioris very helpful for the research and development of safe and effective pharmaceutical formulations. DSC experiments were also carried out with chimeric bilayers (called ?liposomes?), composed of hydrogenated soy phosphatidylcholine (HSPC) and poly(n-butylacrylate)-b-poly(acrylic acid) block copolymer with 70 % content of poly(acrylic acid (PnBA-b-PAA 30/70) with the addition of furosemide at the molar ratio of 9:0.1:1.0 in the system HSPC:PnBA-b-PAA 30/70:furosemide. Chimeric liposomal systems were characterized as ?fluid-like? by their DSC curves, which may be potentially translated as an easy way for release of furosemide from the advanced delivery system.
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Li, Jin Hong, Xiu Wen Wu, and Jing Yang. "Encapsulated Titanium Oxide with Al2O3 and its Ultraviolet Shielding Properties." Key Engineering Materials 373-374 (March 2008): 706–9. http://dx.doi.org/10.4028/www.scientific.net/kem.373-374.706.
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In this work, we encapsulated the titanium oxide particles with a layer of Al2O3 by a sol-gel process and investigated the UV-shielding properties of the obtained Al2O3-TiO2 composites. In this method, Al(NO3)3 aqueous solution mixed with raw titanium oxide powder was hydrolyzed by adding NH3·H2O. The hydrated materials were calcined at 500°C and then the composite of Al2O3-TiO2 was prepared. Different techniques including ICP-AES, XRD, SEM-EDS, and TEM were used to characterize the raw TiO2 and encapsulated TiO2 particles. Chemical analysis showed that TiO2 mass content in the raw titanium oxide particles is 98.25%, and Al2O3 is just 0.75%. After modification, the percentage Al2O3 was increased to 4.48% due to the encapsulation of Al2O3. Trace elements analysis displayed that the concentration of the trace elements were much lower than their original content in the raw titanium oxide, which prove that proved that there was no impurities incorporated into in the sol-gel process. XRD analysis indicated that the modified titanium oxide powders are mainly in phase of rutile, ca. 99.1%, and the profiles exhibit no peaks of crystalline Al2O3 suggesting the layer of Al2O3 exists in amorphous phase. SEM image suggests that the size is in 80~600nm of the raw TiO2 granula and became rougher on the surface, the packing of the agglomerations got looser after modification with Al2O3. HRTEM image shows that the TiO2 particles was evenly coated with a packed layer ~8 nm in thickness. The UV-Vis absorbency experiments showed that the range of wavelength shielded was narrowed from 208-316 nm in the raw titanium oxide to 225-285 nm in the case of the Al2O3-TiO2. The average absorbency of UV was improved from 1.07 to 1.98 at the same content 1.0 μg/mL in the suspended solution. The results reflected that Al2O3 modification process improve the titanium oxide particles UV-shielding properties in selectivity and performance.
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Botsa, Sathish Mohan, Ramadevi Dharmasoth, and Keloth Basavaiah. "A Facile Synthesis of Cu2O and CuO Nanoparticles Via Sonochemical Assisted Method." Current Nanoscience 15, no. 2 (December 14, 2018): 209–13. http://dx.doi.org/10.2174/1573413714666180530085447.
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Background: During past two decades, functional nanomaterials have received great attention for many technological applications such as catalysis, energy, environment, medical and sensor due to their unique properties at nanoscale. However, copper oxide nanoparticles (NPs) such as CuO and Cu2O have most widely investigated for many potential applications due to their wide bandgap, high TC, high optical absorption and non-toxic in nature. The physical and chemical properties of CuO and Cu2O NPs are critically depending on their size, morphology and phase purity. Therefore, lots of efforts have been done to prepare phase CuO and Cu2O NPs with different morphology and size. Method: The synthesis of cupric oxide (CuO) and cuprous oxide (Cu2O) NPs using copper acetate as a precursor by varying the reducing agents such as hydrazine sulphate and hydrazine hydrate via sonochemical method. The phase, morphology and crystalline structure of a prepared CuO and Cu2O NPs were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDS) and UV-Visible Diffuse reflectance spectroscopy (DRS). Results: The phase of NPs was tuned as a function of reducing agents.XRD patterns confirmed the formation of pure phase crystalline CuO and Cu2O NPs. FTIR peak at 621 cm-1 confirmed Cu(I)-O vibrations, while CuO vibrations confirmed by the presence of two peaks at 536 and 586 cm-1. Further investigation was done by Raman, which clearly indicates the presence of peaks at 290, 336, 302 cm-1 and 173, 241 cm-1 for CuO and Cu2O NPs, respectively. The FESEM images revealed rod-like morphology of the CuO NPs while octahedral like shape for Cu2O NPs. The presence of elemental Cu and O in stoichiometric ratios in EDS spectra confirms the formation of both CuO and Cu2O NPs. In summary, CuO and Cu2O NPs were successfully synthesized by a sonochemical method using copper acetate as a precursor at different reducing agents. The bandgap of CuO and Cu2O NPs was 2.38 and 1.82, respectively. Furthermore, the phase purity critically depends on reducing agents.
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Butek, Juraj, Ján Spišiak, and Stanislava Milovská. "Garnet-Vesuvianite Equilibrium in Rodingites from Dobšiná (Western Carpathians)." Minerals 11, no. 2 (February 11, 2021): 189. http://dx.doi.org/10.3390/min11020189.
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Intensively metasomatized rocks from serpentinized ultramafic tectonic fragments in Dobšiná, Western Carpathians, consist of typical rodingite mineral association: hydrated garnet, vesuvianite, diopside and clinochlore. Electron microprobe analysis (EMPA) and Micro-Raman analyses of the main minerals evidence complex mineralogical evolution and variable mineral chemistry. Garnet solid solution is dominated by grossular-andradite series, which demonstrates a significant degree of hydration, mainly for grossular rich garnet cores. Garnet is locally enriched in TiO2 (up to 13 wt%), possibly indicating a chemical relic of a Ti-oxide mineral. Younger, andradite-richer garnet rims demonstrate a low degree of hydration, suggesting a harder incorporation of an (OH)− anion into its crystal structure. Garnet chemical variations display an ideal negative correlation between Al and (Fe3+ + Ti). The most recent mineral phase is represented by euhedral vesuvianite (± chlorite), which crystallizes at the expense of the garnet solid solution. This reaction shows a well-equilibrated character and indicates a high extent of rodingitization process. Chlorite thermometry models suggest an average temperature of late rodingite (trans) formation of about 265 °C.
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Srivastava, Manish, Ashok Kumar Das, Partha Khanra, Nam Hoon Kim, and Joong Hee Lee. "A Facile One-Step Hydrothermal Synthesis of Graphene/CeO2 Nanocomposite and its Catalytic Properties." Advanced Materials Research 747 (August 2013): 242–45. http://dx.doi.org/10.4028/www.scientific.net/amr.747.242.
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Graphene/CeO2 nanocomposite has been successfully prepared by directly growing CeO2 nanoparticles on graphene sheets via in-situ reduction of graphene oxide containing the metal precursor. The presence of cetyltrimethyl ammonium bromide (CTAB) results the formation of CeO2 nanoparticles with a narrow size distribution. The structural, morphological, particles size and optical properties of the synthesized products were investigated through X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR) and UVvis absorbance spectroscopy, respectively. The XRD pattern shows that graphene/CeO2 nanocomposite is highly crystalline in nature. Growth of CeO2 nanoparticles with size in range of 5-18 nm on the graphene sheet were observed by TEM measurement. Optical energy band gap was calculated to be ~3.30 eV corresponding to direct transition. The catalytic activity of the synthesized nanocomposite was investigated taking hydrazine hydrate as a model system. Significant enhancement in the peak current with respect to CeO2 was observed on graphene/CeO2 nanocomposite-based electrode demonstrating the higher catalytic activity of graphene/CeO2 nanocomposite-based electrode.
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Wojnarowicz, Jacek, Agnieszka Opalinska, Tadeusz Chudoba, Stanislaw Gierlotka, Roman Mukhovskyi, Elzbieta Pietrzykowska, Kamil Sobczak, and Witold Lojkowski. "Effect of Water Content in Ethylene Glycol Solvent on the Size of ZnO Nanoparticles Prepared Using Microwave Solvothermal Synthesis." Journal of Nanomaterials 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/2789871.
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Zinc oxide nanoparticles (ZnO NPs) were obtained by the microwave solvothermal synthesis (MSS) method. The precursor of the MSS reaction was a solution of hydrated zinc acetate in ethylene glycol with water addition. It was proved that by controlling the water concentration in the precursor it was possible to control the size of ZnO NPs in a programmed manner. The less the water content in the precursor, the smaller the size of ZnO NPs obtained. The obtained NPs with the average particle size ranging from 25 nm to 50 nm were characterised by homogeneous morphology and a narrow distribution of particle sizes. The following parameters of the obtained ZnO NPs were determined: pycnometric density, specific surface area, phase purity, chemical composition, lattice parameters, average particle size, and particle size distribution. The average size of ZnO NPs was determined using Scherrer’s formula, Nanopowder XRD Processor Demo web application, by converting the results of the specific surface area, and TEM tests using the dark field technique. ZnO morphology and structure were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The test performed by the X-ray powder diffraction (XRD) confirmed that crystalline ZnO, pure in terms of phase, had been obtained.
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A Karim, Siti Shafura, Yuzuru Takamura, Phan Trong Tue, Nguyen Thanh Tung, Jamal Kazmi, Chang Fu Dee, Burhanuddin Yeop Majlis, and Mohd Ambri Mohamed. "Developing Conductive Highly Ordered Zinc Oxide Nanorods by Acetylacetonate-Assisted Growth." Materials 13, no. 5 (March 4, 2020): 1136. http://dx.doi.org/10.3390/ma13051136.
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Highly ordered vertically grown zinc oxide nanorods (ZnO NRs) were synthesized on ZnO-coated SiO2/Si substrate using zinc acetylacetonate hydrate as a precursor via a simple hydrothermal method at 85 °C. We used 0.05 M of ZnO solution to facilitate the growth of ZnO NRs and the immersion time was varied from 0.5 to 4 h. The atomic force microscopy revealed the surface roughness of ZnO seed layer used to grow the ZnO NRs. The morphology of vertically grown ZnO NRs was observed by field emission scanning electron microscopy. X-ray diffraction examination and transmission electron microscopy confirmed that the structure of highly ordered ZnO NRs was crystalline with a strong (002) peak corresponded to ZnO hexagonal wurtzite structure. The growth of highly ordered ZnO NRs was favorable due to the continuous supply of Zn2+ ions and chelating agents properties obtained from the acetylacetonate-derived precursor during the synthesis. Two-point probe current–voltage measurement and UV–vis spectroscopy of the ZnO NRs indicated a resistivity and optical bandgap value of 0.44 Ω.cm and 3.35 eV, respectively. The photoluminescence spectrum showed a broad peak centered at 623 nm in the visible region corresponded to the oxygen vacancies from the ZnO NRs. This study demonstrates that acetylacetonate-derived precursors can be used for the production of ZnO NRs-based devices with a potential application in biosensors.
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Accardo, Grazia, Gianfranco Dell’Agli, Maria Mascolo, Luca Spiridigliozzi, and Sung Yoon. "Controlled Coprecipitation of Amorphous Cerium-Based Carbonates with Suitable Morphology as Precursors of Ceramic Electrolytes for IT-SOFCs." Materials 12, no. 5 (February 27, 2019): 702. http://dx.doi.org/10.3390/ma12050702.
Full textAbstract:
To be suitable as electrolytes in intermediate temperature solid oxide fuel cell (IT-SOFC), ceramic precursors have to be characterized by high sintering aptitude for producing fully densified products which are needed for this kind of application. Therefore, synthesis processes able to prepare highly reactive powders with low costs are noteworthy to be highlighted. It has been shown that amorphous coprecipitates based on cerium doped (and codoped) hydrated hydroxycarbonates can lead to synthesized ceramics with such desired characteristics. These materials can be prepared by adopting a simple coprecipitation technique using ammonium carbonate as precipitating agent. As a function of both the molar ratio between carbonate anions and total metallic cations, and the adopted mixing speed, the coprecipitate can be either amorphous, owning a very good morphology, or crystalline, owning worse morphology, packing aptitude, and sinterability. The amorphous powders, upon a mild calcination step, gave rise to the formation of stable solid solutions of fluorite-structured ceria maintaining the same morphology of the starting powders. Such calcined powders are excellent precursors for sintering ceramic electrolytes at low temperatures and with very high electrical conductivity in the intermediate temperature range (i.e., 500–700 °C). Therefore, irrespective of the actual composition of ceria-based systems, by providing an accurate control of both chemical conditions and physical parameters, the coprecipitation in the presence of ammonium carbonate can be considered as one of the most promising synthesis route in terms of cost/effectiveness to prepare excellent ceramic precursors for the next generation of IT-SOFC solid electrolytes.
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Paal, Mark, Isaac Nkrumah, Francis K. Ampong, David Ngbiche, Robert K. Nkum, and Francis Boakye. "The Effect of Deposition Time and Sulfurization Temperature on The Optical and Structural Properties of Iron Sulfide Thin Films Deposited from Acidic Chemical Baths." Science Journal of University of Zakho 8, no. 3 (September 30, 2020): 97–104. http://dx.doi.org/10.25271/sjuoz.2020.8.3.752.
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Pyrite phase FeS2 thin films have been grown by a two-stage process of chemical bath deposition followed by sulfurization. Thiourea and thioacetamide were used as sulfur precursors in separate baths. The deposition time was controlled for 1, 2, and 3 hours respectively. The as-deposited films were sulfurized at temperatures of 250 oC and 500 oC to form the pyrite phase. The effect of deposition time and sulfurization temperature on the structure, morphology and optical properties of the iron pyrite films obtained from the two separate baths were studied and compared. X-ray diffraction analyses established the formation of the pyrite phase in all the films after sulfurization, in addition to iron (II) oxide hydrate as impurities. All films showed further improvement in pyrite formation, crystallinity as well as an increase in crystallite size after sulfurizing at 500 oC. EDAX and SEM microscopy showed that the iron pyrite films produced from the bath containing thiourea, had better crystallinity and a higher iron content. The optical band gap of the iron pyrite films obtained with thiourea, was 2.1, 1.9 and 1.6 eV for the various deposition times. With thioacetamide, the band gap was 1.4 eV, for the deposition time of 3 hours.
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Artesani, Alessia, Maria Vittoria Dozzi, Lucia Toniolo, Gianluca Valentini, and Daniela Comelli. "Experimental Study on the Link between Optical Emission, Crystal Defects and Photocatalytic Activity of Artist Pigments Based on Zinc Oxide." Minerals 10, no. 12 (December 15, 2020): 1129. http://dx.doi.org/10.3390/min10121129.
Full textAbstract:
The historical knowledge inherited from house paint documents and the experimental research on synthetic pigments show that production methods have an important role in the performance of paint. In this regard, this work investigates the links existing between the optical emission, crystal defects and photocatalytic activity of zinc white pigment from different contemporary factories, with the aim of elucidating the effects of these characteristics onto the tendency of the pigment to induce paint failures. The analysed samples display highly similar crystallite structure, domain size, and specific surface area, whilst white pigments differ from pure ZnO in regards to the presence of zinc carbonate hydrate that is found as a foreign compound. In contrast, the photoluminescence measurements categorize the analysed samples into two groups, which display different trap-assisted emissions ascribed to point crystal defects introduced during the synthesis process, and associated to Zn or O displacement. The photocatalytic degradation tests infer that the emerged defective structure and specific surface area of ZnO-based samples influence their tendency to oxidize organic molecules under light irradiation. In particular, the results indicate that the zinc interstitial defects may be able to promote the photogenerated electron-hole couples separation with a consequent increase of the overall ZnO photocatalytic activity, negatively affecting the binding medium stability. This groundwork paves the way for further studies on the link between the photoluminescence emission of the zinc white pigment and its tendency to decompose organic components contained in the binding medium.
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Kumar, R., R. W. Saunders, A. S. Mahajan, J. M. C. Plane, and B. J. Murray. "Physical properties of iodate solutions and the deliquescence of crystalline I<sub>2</sub>O<sub>5</sub> and HIO<sub>3</sub>." Atmospheric Chemistry and Physics Discussions 10, no. 9 (September 1, 2010): 20823–56. http://dx.doi.org/10.5194/acpd-10-20823-2010.
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Abstract. Secondary aerosol produced from marine biogenic sources in algal-rich coastal locations will initially be composed of iodine oxide species, most likely I2O5, or its hydrated form HIO3, formed as a result of iodine gas-phase chemistry. At present, there is no quantitative hygroscopic data for these compounds and very little data available for iodate solutions (HIO3 and I2O5 share a common aqueous phase). With increased interest in the role of such aerosol in the marine atmosphere, we have conducted studies of (i) the deliquescence behaviour of crystalline HIO3 and I2O5 at 273–303 K, (ii) the efflorescence behaviour of aqueous iodate solution droplets, and (iii) properties (water activity, density, and viscosity) of subsaturated and saturated iodate solutions. The deliquescence of I2O5 crystals at 293 K was observed to occur at a relative humidity (DRH) of 80.8±1.0%, whereas for HIO3, a DRH of 85.0±1.0% was measured. These values are consistent with measured water activity values for saturated I2O5 and HIO3 solutions at 293 K of 0.80±0.01 and 0.84±0.01 respectively. At all temperatures, DRH values for HIO3 crystals were observed to be higher than for those of I2O5. The temperature-dependent DRH data, along with solubility and water activity data were used to evaluate the enthalpy of solution (ΔHsol) for HIO3 and I2O5. A (ΔHsol value of 8.3±0.7 kJ mol−1 was determined for HIO3 which is consistent with a literature value of 8.8 kJ mol−1. For I2O5, we report for the first time its solubility at various temperatures and (ΔHsol=12.4±.6 kJ mol−1. The measured water activity values confirm that aqueous iodate solutions are strongly non-ideal, consistent with previous reports of complex ion formation and molecular aggregation.
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Kumar, R., R. W. Saunders, A. S. Mahajan, J. M. C. Plane, and B. J. Murray. "Physical properties of iodate solutions and the deliquescence of crystalline I<sub>2</sub>O<sub>5</sub> and HIO<sub>3</sub>." Atmospheric Chemistry and Physics 10, no. 24 (December 23, 2010): 12251–60. http://dx.doi.org/10.5194/acp-10-12251-2010.
Full textAbstract:
Abstract. Secondary aerosol produced from marine biogenic sources in algal-rich coastal locations will initially be composed of iodine oxide species, most likely I2O5, or its hydrated form HIO3, formed as a result of iodine gas-phase chemistry. At present, there is no quantitative hygroscopic data for these compounds and very little data available for iodate solutions (HIO3 and I2O5 share a common aqueous phase). With increased interest in the role of such aerosol in the marine atmosphere, we have conducted studies of (i) the deliquescence behaviour of crystalline HIO3 and I2O5 at 273–303 K, (ii) the efflorescence behaviour of aqueous iodate solution droplets, and (iii) properties (water activity, density, and viscosity) of subsaturated and saturated iodate solutions. The deliquescence of I2O5 crystals at 293 K was observed to occur at a relative humidity (DRH) of 80.8±1.0%, whereas for HIO3, a DRH of 85.0±1.0% was measured. These values are consistent with measured water activity values for saturated I2O5 and HIO3 solutions at 293 K of 0.80±0.01 and 0.84±0.01 respectively. At all temperatures, DRH values for HIO3 crystals were observed to be higher than for those of I2O5. The temperature-dependent DRH data, along with solubility and water activity data were used to evaluate the enthalpy of solution (ΔHsol) for HIO3 and I2O5. A ΔHsol value of 8.3±0.7 kJ mol−1 was determined for HIO3 which is consistent with a literature value of 8.8 kJ mol−1. For I2O5, we report for the first time its solubility at various temperatures and ΔHsol = 12.4±0.6 kJ mol−1. The measured water activity values confirm that aqueous iodate solutions are strongly non-ideal, consistent with previous reports of complex ion formation and molecular aggregation.
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Tyumentseva, Olga S., Ilya V. Kornyakov, Sergey N. Britvin, Andrey A. Zolotarev, and Vladislav V. Gurzhiy. "Crystallographic Insights into Uranyl Sulfate Minerals Formation: Synthesis and Crystal Structures of Three Novel Cesium Uranyl Sulfates." Crystals 9, no. 12 (December 9, 2019): 660. http://dx.doi.org/10.3390/cryst9120660.
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An alteration of the uranyl oxide hydroxy-hydrate mineral schoepite [(UO2)8O2(OH)12](H2O)12 at mild hydrothermal conditions was studied. As the result, four different crystalline phases Cs[(UO2)(SO4)(OH)](H2O)0.25 (1), Cs3[(UO2)4(SO4)2O3(OH)](H2O)3 (2), Cs6[(UO2)2(SO4)5](H2O)3 (3), and Cs2[(UO2)(SO4)2] (4) were obtained, including three novel compounds. The obtained Cs uranyl sulfate compounds 1, 3, and 4 were analyzed using single-crystal XRD, EDX, as well as topological analysis and information-based structural complexity measures. The crystal structure of 3 was based on the 1D complex, the topology of which was unprecedented for the structural chemistry of inorganic oxysalts. Crystal chemical analysis performed herein suggested that the majority of the uranyl sulfates minerals were grown from heated solutions, and the temperature range could be assumed from the manner of interpolyhedral linkage. The presence of edge-sharing uranyl bipyramids most likely pointed to the temperatures of higher than 100 °C. The linkage of sulfate tetrahedra with uranyl polyhedra through the common edges involved elevated temperatures but of lower values (~70–100 °C). Complexity parameters of the synthetic compounds were generally lower than that of uranyl sulfate minerals, whose structures were based on the complexes with the same or genetically similar topologies. The topological complexity of the uranyl sulfate structural units contributed the major portion to the overall complexity of the synthesized compounds, while the complexity of the respective minerals was largely governed by the interstitial structure and H-bonding system.
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Zagórska, Urszula, and Sylwia Kowalska. "Crystallization of simonkolleite (Zn5Cl2(OH)8 ∙ H2O) in powder samples prepared for mineral composition analysis by quantitative X-ray diffraction (QXRD)." Nafta-Gaz 77, no. 5 (May 2021): 293–98. http://dx.doi.org/10.18668/ng.2021.05.02.
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The analysis of mineralogical composition by quantitative X-ray diffraction (QXRD) is one of the standard research methods used in hydrocarbon exploration. In order to improve it and to obtain better results, the methodology of quantitative analysis used at Well Logging Department is being periodically (more or less) modified. After the introduction of the improvements, comparative analyses were performed on archival samples. Reflections from an unidentified phase which did not occur in the tested Rotliegend sandstone samples were noticed on X-ray diffractograms of archival samples. Reflections of a mineral called simonkolleite were identified in the X-ray diffraction database. Chemically it is a hydrated zinc chloride of the formula: Zn5Cl2(OH)8 × H2O. Analysis of the composition of samples in which simonkolleite crystallised, indicated that the mineral is being formed in the result of the slow reaction of zinc oxide with halite (NaCl) and water vapour. An attempt was made to determine the influence of the presence of this mineral on the results of the quantitative analysis of mineralogical composition. The above methodology was applied on a group of ten samples. The results of the quantitative analysis conducted for archival samples stored with added zincite standard containing simonkolleite and for new, freshly grinded (without artifact) samples were compared. The comparison of the obtained results showed a slight influence of this mineral on the quantitative composition of the remaining components. The difference between the results usually did not exceed the method error. At the same time a significant difference in the calculated content of the internal standard was noted – on average 1% less in archival than in new samples. This shows that the reaction occurring in the archival samples will affect the evaluation of the quality of the obtained quantitative analysis, at the same time excluding the possibility of determining the rock’s amorphous substance content with the internal standard method.