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Articles de revues sur le sujet « Polycrystalline Oxides »

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Auteur : Grafiati
Publié le 7 septembre 2023

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1

Mukhin, N. V., K. G. Elanskaia, V. M. Pukhova, S. A. Tarasov, K. A. Vorotilov, M. V. Rudenko et A. V. Ermachikhin. « Formation Mechanisms for Hetero-Phase Ferroelectric Films of Lead Zirconate Titanate ». Journal of the Russian Universities. Radioelectronics, no 2 (5 juin 2018) : 26–36. http://dx.doi.org/10.32603/1993-8985-2018-21-2-26-36.

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An experimental and theoretical study of the formation processes of "impurity" phase inclusions in ferroelectric oxides is carried out via example of polycrystalline lead zirconate-titanate (PZT) films. A feature of these compositions is relatively high volatility of lead oxides, which can lead to deficiency of these components in the composition of the ferroelectric film formed during high-temperature crystallization. To avoid lead losses, some excess is added to the solution in the process of synthesis. Experimental samples of PZT films are obtained using sol-gel method with different contents of lead oxide, the crystallization of the ferroelectric phase of the films is carried out in air at 600 °C. In the films, the inclusions of lead oxide impurity phase are found, and the size distribution of these inclusions are obtained. Model concepts are presented and a system of equations is proposed describing the dispersed inclusions formation kinetics of new phases of different stoichiometric composition at the interfaces in polycrystalline films of multicomponent ferroelectric oxides due to bulk diffusion and grain-boundary segregation. Comparison of the experimental data with the theoretical model gives qualitative agreement. The approach generality makes it possible to extend the model to other systems of multicomponent ferroelectric polycrystalline materials.
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2

Pezzotti, Giuseppe. « Internal friction of polycrystalline ceramic oxides ». Physical Review B 60, no 6 (1 août 1999) : 4018–29. http://dx.doi.org/10.1103/physrevb.60.4018.

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3

Vahidi, Hasti, Komal Syed, Huiming Guo, Xin Wang, Jenna Laurice Wardini, Jenny Martinez et William John Bowman. « A Review of Grain Boundary and Heterointerface Characterization in Polycrystalline Oxides by (Scanning) Transmission Electron Microscopy ». Crystals 11, no 8 (28 juillet 2021) : 878. http://dx.doi.org/10.3390/cryst11080878.

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Interfaces such as grain boundaries (GBs) and heterointerfaces (HIs) are known to play a crucial role in structure-property relationships of polycrystalline materials. While several methods have been used to characterize such interfaces, advanced transmission electron microscopy (TEM) and scanning TEM (STEM) techniques have proven to be uniquely powerful tools, enabling quantification of atomic structure, electronic structure, chemistry, order/disorder, and point defect distributions below the atomic scale. This review focuses on recent progress in characterization of polycrystalline oxide interfaces using S/TEM techniques including imaging, analytical spectroscopies such as energy dispersive X-ray spectroscopy (EDXS) and electron energy-loss spectroscopy (EELS) and scanning diffraction methods such as precession electron nano diffraction (PEND) and 4D-STEM. First, a brief introduction to interfaces, GBs, HIs, and relevant techniques is given. Then, experimental studies which directly correlate GB/HI S/TEM characterization with measured properties of polycrystalline oxides are presented to both strengthen our understanding of these interfaces, and to demonstrate the instrumental capabilities available in the S/TEM. Finally, existing challenges and future development opportunities are discussed. In summary, this article is prepared as a guide for scientists and engineers interested in learning about, and/or using advanced S/TEM techniques to characterize interfaces in polycrystalline materials, particularly ceramic oxides.
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Shang, H. M., Ying Wang et Guo Zhong Cao. « Growth of Oxide Nanorod, Nanotube and Nanocable Arrays through Template-Based Sol Electrophoretic Deposition ». Key Engineering Materials 336-338 (avril 2007) : 2122–27. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.2122.

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This paper introduces a process for the growth of oxide nanorod, nanotube, and nanocable arrays that combines sol preparation and template-based electrophoretic deposition. Examples are shown that the sol electrophoretic deposition is an effective method for the formation of polycrystalline and single crystal oxide nanorod arrays, nanotube arrays and conformal coating of thin films of oxides on metal nanorods to produce metal-oxide core-shell nanocable arrays.
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5

Afonin, N. N., et V. A. Logacheva. « Modeling of the reaction interdiffusion in the polycrystalline systems with limited component solubility ». Industrial laboratory. Diagnostics of materials 85, no 9 (28 septembre 2019) : 35–41. http://dx.doi.org/10.26896/1028-6861-2019-85-9-35-41.

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that may be accompanied by the processes of mutual diffusion and phase formation. Controlled technological process of forming coatings with the given properties entails the necessity of forecasting the evolution of the phase composition. This in turn requires the development of algorithms and quantitative models of the processes. Reactive mutual diffusion in polycrystalline metal (oxide film systems with limited component solubility) has not been simulated before. The simulation allows selecting the annealing conditions (time and temperature) necessary for the inclusion and uniform distribution of metal in the oxide lattice. A quantitative model of the interaction in a multi-layer system metal — polycrystalline oxide of the other metal under conditions of limited solubility is developed. The model is based on the concepts of mutual diffusion of the components and the bulk reactions of the formation of complex oxides. The developed model was applied to the analysis of the process of modifying thin films of titanium oxide with transition metals. The model allowed us to perform a numerical analysis of the experimental concentrations of the component distributions in polycrystalline Co - Ti02 and Fe - Ti02 thin-film systems. The individual diffusion coefficients of the studied metals and titanium under conditions of vacuum annealing were determined. The model provides a good description of the basic systematic features of the process: the appearance of titanium in the metal film and deep penetration of Fe and Co into the film of titanium oxide. It also explains the fact that complex oxides are formed not by layer-by-layer growth at the metal-oxide interface, but throughout the entire thickness of Ti02 film. The results of analysis of the processes of interracial interaction in layered systems accompanied by the reaction mutual diffusion can be used to predict the evolution of the phase composition, as well as to control the technological processes of obtaining materials with the desired properties.
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6

Tsoga, A., D. Sotiropoulou et P. Nikolopoulos. « Grain Boundary Grooving in Polycrystalline Oxides and Surface Diffusion Coefficient in Polycrystalline Alumina ». Materials Science Forum 207-209 (février 1996) : 565–68. http://dx.doi.org/10.4028/www.scientific.net/msf.207-209.565.

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Hilson, Gabrielle, Keith R. Hallam et Peter E. J. Flewitt. « The Measurement of Stresses within Oxides Produced on Austenitic and Ferritic Steels Using Raman Spectroscopy ». Materials Science Forum 524-525 (septembre 2006) : 957–62. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.957.

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Raman spectroscopy has been used by various workers to provide a measure of the stresses within the oxides grown on metal substrates at high temperatures. In this paper, we consider thermally grown oxides produced on a Type 316 austenitic stainless steel and an iron 3% silicon ferritic steel. The oxides were grown in air at temperatures of 950oC and 650oC respectively over a range of times. These oxides have been characterised by producing cross-sections using focused ion beam milling. The variation of the Raman spectra wave number (He, Ne laser; λ = 633nm) for the oxides produced on the polycrystalline austenitic stainless steel and the ferritic steel were measured as a function of oxide thickness. This shift in wave number was a function of stress. For a fixed oxide thickness on the stainless steel substrate the specimen has been subject to a bending force. A back face strain gauge fixed to the metal substrate provided a measure of the applied strain. The peak wave number varied with applied strain. The results are discussed with respect to the potential to characterise the stresses produced in thermally grown oxides and as a tool to monitor applied stress.
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8

Lee, J. C., et C. Hu. « Polarity asymmetry of oxides grown on polycrystalline silicon ». IEEE Transactions on Electron Devices 35, no 7 (juillet 1988) : 1063–70. http://dx.doi.org/10.1109/16.3365.

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Pobol, Igor, Inessa Gontcharova et Jaroslaw Rajczyk. « Nanostructured Metallic Coatings for Protection of Materials against Mould Attack ». Advanced Materials Research 1020 (octobre 2014) : 55–59. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.55.

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To prevent materials from mould damage nanostructured metallic coatings were used. Silver, copper and titanium coatings were deposited on different materials. Deposition of metal from plasma flow, generated by vacuum-arc discharge, forms coating with highly dispersed polycrystalline structure. Average size of metal grains in copper or titanium coatings is ~10-15 nm, in silver coatings it reaches ~ 20-25 nm. Both paper and plastic materials with nanostructured metallic coatings showed high fungitoxicity unlike the same metal plates. The reason of that phenomenon may be that during oxygen chemisorption oxides of metals occur. Metals and their oxides formed coating with a highly polycrystalline structure and their fungi toxicity can vary.
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10

Nguyen, Viet Huong, Ulrich Gottlieb, Anthony Valla, Delfina Muñoz, Daniel Bellet et David Muñoz-Rojas. « Electron tunneling through grain boundaries in transparent conductive oxides and implications for electrical conductivity : the case of ZnO:Al thin films ». Materials Horizons 5, no 4 (2018) : 715–26. http://dx.doi.org/10.1039/c8mh00402a.

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Smith, David, Sylvie Grandjean, Joseph Absi, Stephanie Kadiebu et Sylvain Fayette. « Grain-boundary thermal resistance in polycrystalline oxides : alumina, tin oxide, and magnesia ». High Temperatures-High Pressures 35/36, no 1 (2003) : 93–99. http://dx.doi.org/10.1068/htjr084.

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Oranska, O. I., Yu I. Gornikov, V. M. Gun’ko et A. V. Brichka. « On the use of model diffraction profiles in the microstructure analysis of nanocrystalline metal oxides based on powder x-ray diffraction data ». SURFACE 14(29) (30 décembre 2022) : 148–58. http://dx.doi.org/10.15407/surface.2022.14.148.

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The study of the microstructure of nanocrystalline substances by the method of powder diffractometry based on the physical broadening of diffraction lines involves the use of diffraction data of standard polycrystalline samples, preferably, one nature with the test samples with the size of crystallites exceeding 100 nm. In the absence of such standards, researchers resort to the existing dependence of the width of diffraction peaks on the angle of diffraction for the standard sample or the construction of theoretical instrumental profiles due to the collimation parameters of x -rays used. In this paper a comparative study of the microstructure of nanocrystalline titanium oxide (anatase), tin oxide iron oxide (magnetite), synthesized in various ways, using several methods of analysis of powder diffractograms, was carried out. To evaluate the average crystallite sizes of the studied oxides, the Sherer equation with a graphical method of determining the width of instrumental profile and the influence of dublet radiation was chosen. Methods of profile analysis of diffraction spectra, such as a method of whole profile modeling of powder diffractograms (WPPM) and the chord method, were used to construct crystallite size distribution functions and determine the average size of crystallites of the oxides. Modeling of instrumental diffraction profiles of titanium, tin and iron oxides was performed using X -rays collimation parameters determinated using a polycrystalline silicon as standard and pseudo -Voigt function, which best describes the form of diffraction peak. The crystallite size distribution functions were constructed by means of WPPM and chords methods based on the instrumental profiles. It has been found that the values of average size of the crystallites, obtained by the methods of Sherer, WPPM and chords, differ within the one order of magnitude for each oxide. Thus, for titanium oxide this value is within 12-18 nm, for tin oxide within 7-10 nm, the iron oxide of iron within 9-12 nm. Analysis of size crystallite distribution functions and average sizes of the crystallites of the studied oxides showed the advisability of using different methods of studying microstructure to clarify the true type of the size crystallites distribution and establish its connection with the conditions and the synthesis method.
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Salam, M. Abdus, Suriati Sufian et T. Murugesan. « Synthesis and Characterization of Nano-Structured Mixed Oxides ». Applied Mechanics and Materials 446-447 (novembre 2013) : 196–200. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.196.

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Nano-structured hydrotalcite based mixed oxides have been synthesized using coprecipitation method under variable pH and low supersaturation condition. XRD technique has been used to confirm the hydrotalcite structure and its derived different phase of mixed oxides. The metal dispersion of mixed oxides was analyzed using ICP-MS. The nanostructures of the mixed oxides have been investigated using FESEM and HRTEM. The textural properties of mixed oxides were analyzed using N2 adsorption-desorption (BET) technique. The Characterizations have revealed that the developed mixed oxides were consisted with hexagonal/rhombohedral well dispersed nano-particles. Polycrystalline mixed oxides formed mesopore surface and narrower pore size distribution.
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14

Wang, Xiao, et Alfred Ludwig. « Recent Developments in Small-Scale Shape Memory Oxides ». Shape Memory and Superelasticity 6, no 3 (26 août 2020) : 287–300. http://dx.doi.org/10.1007/s40830-020-00299-7.

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Abstract This review presents an overview of the developments in small-scale shape memory materials: from alloys to oxides and ceramics. Shape memory oxides such as zirconia, different ferroelectric perovskites and VO2-based materials have favorable characteristics of high strength, high operating temperature and chemical resistance, which make this class of shape memory materials interesting for special applications, e.g., in harsh environments or at the nanoscale. Because of the constraint and mismatch stress from neighboring grains in polycrystalline/bulk oxides, the transformation strain of shape memory oxides is relatively small, and micro-cracks can appear after some cycles. However, recent progress in shape memory oxide research related to small-scale approaches such as decreasing the amounts of grain boundaries, strain-engineering, and application in the form of nanoscale thin films shows that some oxides are capable to exhibit excellent shape memory effects and superelasticity at nano/micro-scales. The materials systems ZrO2, BiFO3, and VO2 are discussed with respect to their shape memory performance in bulk and small-scale.
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15

Uhrmacher, Michael, et Klaus-Peter Lieb. « Phase Transitions in Oxides Studied by Perturbed Angular Correlation Spectroscopy ». Zeitschrift für Naturforschung A 55, no 1-2 (1 février 2000) : 90–104. http://dx.doi.org/10.1515/zna-2000-1-217.

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Radioactive atoms located on cation sites in oxide matrices can be used to monitor phase transitions by measuring the electric or magnetic hyperfine interactions by means of Perturbed Angular Correlations spectroscopy. The article illustrates three types of phase transitions studied with 111In tracers and their daughter nuclei 111Cd, namely magnetic, structural and REDOX phase transitions in binary and ternary polycrystalline or single-crystalline oxides. In this context, we also discuss the question of identifying the probes' lattice site(s), the scaling of the Electric Field Gradients in oxides, the influence of the (impurity) probes themselves on the phase transitions, and the occurrence and mechanisms of dynamic interactions. Recent results on 111In in pure and Li-doped In2S3 will also be presented.
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Phani, K. K., et S. K. Niyogi. « Elastic Modulus-Porosity Relation in Polycrystalline Rare-Earth Oxides ». Journal of the American Ceramic Society 70, no 12 (décembre 1987) : C—362—C—366. http://dx.doi.org/10.1111/j.1151-2916.1987.tb04920.x.

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Kim, Bong-soo, Sayong Hong et David W. Lynch. « Inverse-photoemission measurement of iron oxides on polycrystalline Fe ». Physical Review B 41, no 17 (15 juin 1990) : 12227–29. http://dx.doi.org/10.1103/physrevb.41.12227.

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18

Payne, Brad P., Andrew P. Grosvenor, Mark C. Biesinger, Brad A. Kobe et N. Stewart McIntyre. « Structure and growth of oxides on polycrystalline nickel surfaces ». Surface and Interface Analysis 39, no 7 (2007) : 582–92. http://dx.doi.org/10.1002/sia.2565.

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Yoshida, Hidehiro, Koji Morita, Byung Nam Kim et Keijiro Hiraga. « Grain Boundary Nanostructure and High Temperature Plastic Flow in Polycrystalline Oxide Ceramics ». Materials Science Forum 638-642 (janvier 2010) : 1731–36. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1731.

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High temperature creep and superplastic flow in high-purity, polycrystalline oxide ceramics is very sensitive to a small amount of doping by various oxides. The doping effect is attributed to change in grain boundary diffusivity owing to grain boundary segregation of the doped cations. The doping effect on the grain boundary diffusivity is caused mainly by change of chemical bonding state in the vicinity of the grain boundary segregated with the doped cations. In other words, controlling of grain boundary nanostructure based on the doping process will be a useful way to develop new high-performance functional ceramics in the near future.
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Yoshida, Hidehiro, Koji Morita, Byung Nam Kim, Keijiro Hiraga, Takahisa Yamamoto, Yuichi Ikuhara et Taketo Sakuma. « High Temperature Plastic Flow and Ductility in Polycrystalline Oxide Ceramics : Doping Effect and Related Phenomena ». Advances in Science and Technology 45 (octobre 2006) : 1620–25. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1620.

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High temperature creep and superplastic flow in high-purity oxide ceramics such as alumina and tetragonal zirconia polycrystals is very sensitive to a small amount of doping by various oxides. High-resolution transmission electron microscopy and an energy-dispersive X-ray spectroscopy analysis revealed that grain boundaries in high-purity oxide ceramics are free from amorphous phase, and that the doped cations tend to segregate along the grain boundaries. Since the high temperature plastic flow in oxide ceramics takes place mainly by grain boundary matter transport by atomic diffusion, the grain boundary nano-structure control must be a useful way to develop new high-performance functional ceramics in the near future.
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21

Koinuma, Michio, Tomohiko Hirae et Yasumichi Matsumoto. « Electrochemical preparation of cobalt oxide using an autoclave electrolytic cell ». Journal of Materials Research 13, no 4 (avril 1998) : 837–39. http://dx.doi.org/10.1557/jmr.1998.0109.

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Polycrystalline films of cobalt oxides (Co3O4and CoOOH) with and without Sm were fabricated on platinum substrates by electrochemical oxidation in an autoclave. The cobalt oxides were directly crystallized at temperatures higher than about 100 °C during electrolysis. The composition of the cobalt oxides strongly depended on the electrode potential; i.e., Co3O4and CoOOH were formed in non-noble and relatively noble potential regions, respectively. When Sm was incorporated in the CoOOH by the electrolysis in solutions containing Sm3+, only theclattice constant was increased due to an expansion in the layer structure.
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LEOY, C. C., EWH KAN, J. ARIANTO, W. K. CHOI, A. T. S. WEE et Y. J. LIU. « OXIDATION STUDY OF RF SPUTTERED AMORPHOUS AND POLYCRYSTALLINE SILICON GERMANIUM FILMS ». International Journal of Modern Physics B 16, no 28n29 (20 novembre 2002) : 4224–27. http://dx.doi.org/10.1142/s0217979202015133.

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Oxidation study of rf sputtered amorphous and polycrystalline silicon germanium ( Si 1-x Ge x ) film which was conducted using infrared spectroscopy (FTIR). The oxidation results showed linear oxidation rate of amorphous Si 1-x Ge x and polycrystalline Si 1-x Ge x films in the dry oxygen ambient did not depend on the Ge concentration. We found that Ge nanocrystals were formed from mixed ( Si , Ge ) O 2 oxides when annealed in forming gas (10% H 2 + N 2) while pure N 2 showed formation of Ge clusters.
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Briant, C. L., J. A. DeLuca, P. L. Karas, M. F. Garbauskas, J. A. Sutliff, A. Goyal et D. Kroeger. « The microstructural evolution of a silver-containing spray deposited 1223 Tl–Ca–Ba–Cu oxide superconductor ». Journal of Materials Research 10, no 4 (avril 1995) : 823–42. http://dx.doi.org/10.1557/jmr.1995.0823.

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This paper reports a study of the microstructural evolution of Ag-containing 1223 Tl-Ca-Ba-Cu oxide superconductors in spray-deposited films. The films were formed by spray depositing nitrates of Ca, Ba, Cu, and Ag onto a polycrystalline yttria-stabilized zirconia substrate. These deposits were then converted to a mixture of oxides (calcia, calcium-copper oxide, and barium cuprate) and metallic silver by heating in oxygen. When thallium oxide vapor was passed over the film, the thallium was incorporated into the film and the 1223 phase was formed. The evidence strongly suggests that the development of the 1223 superconductor involves the formation of a liquid phase. Our analysis suggests that the initial phase to form a liquid is CaO which contains thallium, barium, copper, and silver. Once this initial liquid is formed, it incorporates more thallium which, in turn, allows it to dissolve other types of oxides present in the film. In this way the liquid spreads across the surface. The equilibrium 1223 phase precipitates from it.
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24

Cascos, V., R. Martínez-Coronado, M. T. Fernández-Díaz et J. A. Alonso. « Topotactic Oxidation of Perovskites to Novel SrMo1-xMxO4−δ (M = Fe and Cr) Deficient Scheelite-Type Oxides ». Materials 13, no 19 (6 octobre 2020) : 4441. http://dx.doi.org/10.3390/ma13194441.

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New polycrystalline SrMo1−xMxO4−δ (M = Fe and Cr) scheelite oxides have been prepared by topotactical oxidation, by annealing in air at 500 °C, from precursor perovskites with the stoichiometry SrMo1−xMxO3−δ (M = Fe and Cr). An excellent reversibility between the oxidized Sr(Mo,M)O4−δ scheelite and the reduced Sr(Mo,M)O3−δ perovskite phase accounts for the excellent behavior of the latter as anode material in solid-oxide fuel cells. A characterization by X-ray powder diffraction (XRD) and neutron powder diffraction (NPD) has been carried out to determine the crystal structure features. The scheelite oxides are tetragonal, space group I41/a (No. 88). The Rietveld-refinement from NPD data at room temperature shows evidence of oxygen vacancies in the structure, due to the introduction of Fe3+/Cr4+ cations in the tetrahedrally-coordinated B sublattice, where Mo is hexavalent. A thermal analysis of the reduced perovskite (SrMo1−xMxO3−δ) in oxidizing conditions confirms the oxygen stoichiometry obtained by NPD data; the stability range of the doped oxides, below 400–450 °C, is lower than that for the parent SrMoO3 oxide. The presence of a Mo4+/Mo5+ mixed valence in the reduced SrMo1−xMxO3−δ perovskite oxides confers greater instability against oxidation compared with the parent oxide. Finally, an XPS study confirms the surface oxidation states of Mo, Fe, and Cr in the oxidized samples SrMo0.9Fe0.1O4-δ and SrMo0.8Cr0.2O4-δ.
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Yu, Feng, Yi Wang, Cong Guo, He Liu, Weizhai Bao, Jingfa Li, Panpan Zhang et Faxing Wang. « Spinel LiMn2O4 Cathode Materials in Wide Voltage Window : Single-Crystalline versus Polycrystalline ». Crystals 12, no 3 (24 février 2022) : 317. http://dx.doi.org/10.3390/cryst12030317.

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Single-crystal (SC) layered oxides as cathodes for Li-ion batteries have demonstrated better cycle stability than their polycrystalline (PC) counterparts due to the restrained intergranular cracking formation. However, there are rare reports on comparisons between single-crystal LiMn2O4 (SC-LMO) and polycrystalline LiMn2O4 (PC-LMO) spinel cathodes for Li-ion storage. In this work, the Li-ion storage properties of spinel LiMn2O4 single-crystalline and polycrystalline with similar particle sizes were investigated in a wide voltage window of 2–4.8 V vs. Li/Li+. The SC-LMO cathode exhibited a specific discharge capacity of 178 mA·h·g−1, which was a bit larger than that of the PC-LMO cathode. This is mainly because the SC-LMO cathode showed much higher specific capacity in the 3 V region (Li-ion storage at octahedral sites with cubic to tetragonal phase transition) than the PC-LMO cathode. However, unlike layered-oxide cathodes, the PC-LMO cathode displayed better cycle stability than the SC-LMO cathode. Our studies for the first time demonstrate that the phase transition-induced Mn(II) ion dissolution in the 3 V region rather than cracking formation is the limiting factor for the cycle performance of spinel LiMn2O4 in the wide voltage window.
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26

Lee, Minyoung, et Donald G. Flom. « Hardness of Polycrystalline Tungsten and Molybdenum Oxides at Elevated Temperatures ». Journal of the American Ceramic Society 73, no 7 (juillet 1990) : 2117–18. http://dx.doi.org/10.1111/j.1151-2916.1990.tb05281.x.

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Diamandescu, Lucian, Doina Mihaila-Tarabasanu, Nicoleta Popescu-Pogrion, Alina Totovina et Ion Bibicu. « Hydrothermal synthesis and characterization of some polycrystalline α-iron oxides ». Ceramics International 25, no 8 (décembre 1999) : 689–92. http://dx.doi.org/10.1016/s0272-8842(99)00002-4.

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Gusarov, V. V., et I. Yu Popov. « Dynamic structure formation during high-temperature deformation of polycrystalline oxides ». Russian Physics Journal 38, no 8 (août 1995) : 825–30. http://dx.doi.org/10.1007/bf00559286.

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29

Afifi, M. A., M. M. Abdel-Aziz, I. S. Yahia, M. Fadel et L. A. Wahab. « Transport properties of polycrystalline TiO2 and Ti2O3 as semiconducting oxides ». Journal of Alloys and Compounds 455, no 1-2 (mai 2008) : 92–97. http://dx.doi.org/10.1016/j.jallcom.2007.01.156.

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30

Dixit, B. B., P. D. Vyas, W. S. Khokle, K. Mahadevan et H. N. Acharya. « Electrical and structural characteristics of oxides grown from polycrystalline silicon ». Bulletin of Materials Science 8, no 3 (juin 1986) : 307–13. http://dx.doi.org/10.1007/bf02744137.

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31

Brito, Pedro, Haroldo Pinto, André Rothkirch et Anke Pyzalla. « Growth Stresses and Phase Development in Nanostructured Oxide Scales Formed on Iron Aluminides ». Materials Science Forum 638-642 (janvier 2010) : 2903–8. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.2903.

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The evolution of phase composition and growth stresses in oxide scales growing on the polycrystalline Fe-15at.%Al alloy at 700°C in air was studied by in-situ synchrotron X-ray diffraction and X-ray photoelectron spectroscopy. The oxidation kinetics was determined by thermogravimetry. The results showed that, under these conditions, metastable -Al2O3 appears only during the first minutes of oxidation and the main oxides formed since the early oxidation are -Al2O3 and -Fe2O3. High volume fractions of -Fe2O3 caused accelerated oxidation rates in the first hours. -Al2O3 and -Fe2O3 grow epitaxially, evolving compressive and tensile growth stresses, respectively.
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Ellmer, Klaus, et Rainald Mientus. « Carrier transport in polycrystalline transparent conductive oxides : A comparative study of zinc oxide and indium oxide ». Thin Solid Films 516, no 14 (mai 2008) : 4620–27. http://dx.doi.org/10.1016/j.tsf.2007.05.084.

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Idczak, Rafał, Karolina Idczak et Robert Konieczny. « Corrosion of Polycrystalline Fe-Si Alloys Studied by TMS, CEMS, and XPS ». Corrosion 74, no 6 (7 janvier 2018) : 623–34. http://dx.doi.org/10.5006/2676.

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The high-temperature corrosion behavior of three polycrystalline Fe-Si alloys containing approximately 4, 5, and 10 at% Si was studied using transmission Mössbauer spectroscopy (TMS), conversion electron Mössbauer spectroscopy (CEMS), and x-ray photoelectron spectroscopy (XPS). The XPS measurements reveal the strong segregation process of silicon atoms to the surface. Moreover, the obtained XPS results suggest that the presence of adsorbed oxygen on the Fe-Si surface effectively enhances the silicon segregation process. On the other hand, the obtained TMS and CEMS spectra show that even 10% of silicon atoms dissolved in the iron matrix do not prevent high-temperature corrosion of the studied Fe-Si alloys. During exposure to air at 870 K, a systematic growth of an α-Fe2O3 compound was observed. Finally, the Mössbauer results show that, during exposure to air, oxygen atoms diffuse to the studied polycrystalline materials not only through the oxide/metal interface on the surface but also along the grain boundaries. Such effects result in the formation of iron oxides in deeper parts of the alloy.
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Lee, Ming Kwei, Chih Feng Yen, Tsung Hsiang Shih, Chen Lia Ho, Hung Chang Lee, Hwai Fu Tu et Cho Han Fan. « Electrical Characteristics of Fluorine Passivated MOCVD-TiO2 Film on (NH4)2Sx Treated GaAs ». Key Engineering Materials 368-372 (février 2008) : 232–34. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.232.

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The high Dit is the major problem of III-V compound semiconductor MOSFET, which causes the pinning of the surface Fermi level near the middle of the energy gap. The GaAs with (NH4)2Sx treatment (S-GaAs) can remove the native oxides on GaAs and prevent it from oxidizing. The electrical characteristics of fluorinated polycrystalline TiO2 films deposited on p-type(100) S-GaAs were investigated. The fluorine from liquid phase deposition solution can passivate the grain boundary of polycrystalline TiO2 prepared by MOCVD. The leakage current through the grain boundaries was suppressed. The leakage current of MOCVD-TiO2/S-GaAs can be improved from 6.8 x 10-6 and 0.2 A/cm2 to 3.41 x 10-7 and 1.13 x 10-6A/cm2 under positive and negative electric fields at 1.5 MV/cm, respectively. Dit and k can be improved from 1.44 x 1012 cm-2eV-1 to 4.6 x 1011 cm-2eV-1 and 52 to 65, respectively. The effective oxide charges can be improved from 2.5 x 1012 C/cm-2 to 9.3 x 1011 C/cm-2.
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35

Akedo, Jun. « Aerosol Deposition Method for Fabrication of Nano Crystal Ceramic Layer ». Materials Science Forum 449-452 (mars 2004) : 43–48. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.43.

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Aerosol deposition method (ADM) for shock-consolidation of fine ceramics powder to form dense and hard layers is reported. Submicron ceramic particles were accelerated by gas flow in the nozzle up to velocity of several hundred m/s. During interaction with substrate, these particles formed thick (10 ~ 100 µm), dense, uniform and hard ceramics layers. Depositions were fulfilled at room temperature. Every layer has polycrystalline structure with nano-meter order scale.􀀂 The results of fabrications, microstructure, mechanical and electrical properties of oxides (α-Al2O3; Pb(Zr0.52,Ti0.48)O3 etc.) and non-oxides materials are presented.
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Liu, Li, Ying Li et Fu Hui Wang. « Influence of Micro-Structure on Oxidation Behavior of a Ni-Based Superalloy at 1000°C ». Materials Science Forum 595-598 (septembre 2008) : 87–94. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.87.

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The isothermal and cyclic oxidation behaviors of a Ni-based superalloy with singlecrystalline (SC), polycrystalline and nanocrystalline (NC) structures were studied at 1000°C. Results indicated that a uniform oxides scale consisted of external Cr2O3 with little TiO2 and internal continuous Al2O3 formed on SC alloy. A non-uniform external oxide of which some locations were nodule-like scale was formed on surface of cast alloy. The nodule-like parts consisted of TiO2, Cr2O3 and serious internal oxidation of Al, and rest flat surface was a Cr2O3 and Al2O3 layer. A continuous Al2O3 layer formed on the sputtered NC coating. The micro-structure influenced the oxidation mechanism and resulted in different oxide scale formed on three materials, which greatly influenced materials’ oxidation and cyclic-oxidation resistance.
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Wodecka-Dus, Beata, Jolanta Dzik, Henryk Bernard, Katarzyna Osinska, Agata Lisińska-Czekaj et Dionizy Czekaj. « Application of Impedance Spectroscopy for Bi1−xNdxFeO3 Ceramics Characterization ». Materials Science Forum 730-732 (novembre 2012) : 71–75. http://dx.doi.org/10.4028/www.scientific.net/msf.730-732.71.

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In the present paper the synthesis conditions for fabrication of Bi1−xNdxFeO3ceramics are reported. The single phase polycrystalline samples of Bi1−xNdxFeO3 were prepared by standard solid state reaction method from the mixture of oxides viz.: Bi2O3, Fe2O3and Nd2O3. The samples were characterized by impedance spectroscopy in the frequency range 10Hz – 1MHz at room temperature.
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Beleznai, Cs, D. Vouagner, J. P. Girardeau-Montaut et L. Nánai. « Laser-induced desorption of various tungsten oxides on polycrystalline W surfaces ». Applied Surface Science 138-139 (janvier 1999) : 512–16. http://dx.doi.org/10.1016/s0169-4332(98)00473-5.

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Moriyama, Takumi, Sohta Hida, Takahiro Yamasaki, Takahisa Ohno, Satoru Kishida et Kentaro Kinoshita. « Experimental and Theoretical Studies of Resistive Switching in Grain Boundaries of Polycrystalline Transition Metal Oxide Film ». MRS Advances 2, no 4 (2017) : 229–34. http://dx.doi.org/10.1557/adv.2017.7.

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ABSTRACTPractical use of Resistive Random Access Memory (ReRAM) depends on thorough understanding of the resistive switching (RS) mechanism in polycrystalline metal oxide films. Based on experimental and theoretical results of NiO based ReRAM, we have proposed a grain surface tiling model, in which grain surfaces (i.e. grain boundaries) are composed by insulating and conductive micro surface structures. This paper reports the adequacy of our model to the NiO based ReRAM and universality of surface electronic properties in metal oxides of NiO, CoO and MgO. Experimental results of RS operating modes suggest that the resistance changes in the grain boundaries, supporting our model. First-principles calculation results suggest that our model can be adopted to other metal oxide materials and the RS from a low resistance to a high resistance can be caused at 1000 K, which agrees with previous experimental reports.
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CHEN, HAO-LONG, et KO-CHENG TSENG. « OBSERVATION OF NANOSCALED ZnO GROWTH ON POLYCRYSTALLINE Zn METAL SHEET PREPARED BY ATMOSPHERIC-PRESSURE PLASMA JET ». International Journal of Nanoscience 09, no 04 (août 2010) : 335–39. http://dx.doi.org/10.1142/s0219581x10006910.

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Nanoscaled zinc oxides were grown on a polycrystalline Zn metal sheet by using an atmospheric-pressure plasma jet (APPJ) with pure oxygen as the reaction gas in an ambient environment. The initial growth formed nanoparticles on the polycrystalline Zn substrate. The nanoscaled ZnO growth process was as follows: nanoparticles, nanocrystal clusters, and then nanocrystal columns with increasing plasma treatment times. The morphologies of nanoscaled ZnO resembled bulbs, long-legged tetrapods, and multipods. The morphologies and structures of the nanoscaled ZnO thus obtained were investigated by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and grazing-incidence X-ray diffraction (GIXRD). The possible growth mechanisms of nanoscaled ZnO are discussed in this paper.
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S. Mofarah, Sajjad, Esmaeil Adabifiroozjaei, Yuan Wang, Hamidreza Arandiyan, Raheleh Pardehkhorram, Yin Yao, M. Hussein N. Assadi et al. « Assembly of cerium-based coordination polymer into variant polycrystalline 2D–3D CeO2−x nanostructures ». Journal of Materials Chemistry A 8, no 9 (2020) : 4753–63. http://dx.doi.org/10.1039/c9ta11961b.

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Yang, Dong Fang. « Pulsed Laser Deposition of Pseudocapacitive Metal Oxide Thin Films for Supercapacitor Applications ». Materials Science Forum 706-709 (janvier 2012) : 884–89. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.884.

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Thin films of manganese oxides have been prepared by pulsed laser deposition (PLD) process on silicon and stainless steel substrates at different substrate temperatures and oxygen gas pressures. By proper selection of temperature and oxygen pressure during the PLD process, pure phases of Mn2O3, Mn3O4 as well as an amorphous phase of MnOx were successfully fabricated and characterized by X-ray diffraction. The pseudo-capacitance behaviors of those manganese oxides of different phases have also been evaluated by the electrochemical cyclic voltammetry in 0.1 M Na2SO4 aqueous electrolyte. Their specific current and capacitance determined at different scan rates were calculated and compared. The results show that polycrystalline Mn2O3 phase has the highest specific current and capacitance, while the values for polycrystalline Mn3O4 films are the lowest. The amorphous phase MnOx films have the values sitting in between those of Mn2O3 and Mn3O4. The specific capacitance of Mn2O3 films reaches 200 F/g at 1 mV/sec scan with excellent stability and cyclic durability. This work has demonstrated that PLD is a very promising technique for supercapacitor material research due to its excellent flexibility and capability of controlling microstructures and phases of various materials.
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Zhao, Tingting, Haoran Yu, Xuyingnan Tao, Feiyang Yu, Ming Li et Haiqian Wang. « Influences of Ni Content on the Microstructural and Catalytic Properties of Perovskite LaNixCr1−xO3 for Dry Reforming of Methane ». Catalysts 12, no 10 (29 septembre 2022) : 1143. http://dx.doi.org/10.3390/catal12101143.

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Perovskite oxides were widely used as precursors for developing metal-support type catalysts. It is attractive to explore the catalytic properties of the oxides themselves for dry reforming of methane (DRM). We synthesized LaNixCr1−xO3 (x = 0.05–0.5) samples in powder form using the sol-gel self-combustion method. Ni atoms are successfully doped into the LaCrO3 perovskite lattice. The perovskite grains are polycrystalline, and the crystallite size decreases with increasing Ni content. We demonstrated that the LaNixCr1−xO3 perovskites show intrinsically catalytic activity for DRM reactions. Reducing the Ni content is helpful to reduce carbon deposition resulting from the metal Ni nanoparticles that usually coexist with the highly active perovskite oxides. The CH4 conversion over the LaNi0.1Cr0.9O3 sample reaches approximately 84% at 750 °C, and the carbon deposition is negligible.
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Kasenov, B. K. « SYNTHESIS AND X-RAY INVESTIGATION OF NOVEL NANOSTRUCTURED COPPER-ZINC MANGANITES OF LANTHANUM AND ALKALI METALS ». Eurasian Physical Technical Journal 18, no 1 (30 mars 2021) : 29–33. http://dx.doi.org/10.31489/2021no1/29-33.

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The aim of this work is to synthesize new nanostructured copper-zinc lanthanum and alkaline metal manganites. Polycrystalline copper-zinc manganites of lanthanum and alkali metals were synthesized by the method of ceramic technology from lanthanum (III), copper (II), zinc (II), manganese (III) oxides, and lithium, sodium, and potassium carbonates in the range of 800-1200 oC. Nanostructured particles were obtained by grinding the synthesized polycrystalline compounds at the «MM301» vibration mill of «Retsch» (Germany). By indexing X-ray images of nanostructured copper-zinc lanthanum and alkaline metal manganites, it was found that they crystallize in cubic syngony. Their lattice parameters are determined. There is a pattern in the change of the lattice parameters from the ionic radii of alkaline metals.
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Francis, Santhanam, Ramachandran Saravanan et Mohammed Açıkgöz. « Solubility Limit of Sol–Gel Grown Nano Zn1-xMgxO Through Charge Density Distribution ». Zeitschrift für Naturforschung A 68, no 10-11 (1 novembre 2013) : 668–76. http://dx.doi.org/10.5560/zna.2013-0043.

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The mixed oxides Zn1-xMgxO were prepared as polycrystalline powders with various compositions (x = 0:02, 0.04, 0.05, and 0.10) using sol-gel technique. X-ray diffractometer (XRD) was used to characterize the powders for structural and electronic properties. X-ray diffraction analysis reveals that all the prepared samples exhibit the single wurtzite phase of zinc oxide (ZnO), and magnesiumdoping does not induce any secondary phase in the samples. The Bragg peak positions in the XRD patterns are found to be shifted towards higher 2q values with more addition of magnesium in the zinc oxide lattice. Magnesium addition in the zinc oxide lattice is found to enhance the mid bond electron density distribution up to x = 0:05 and then decrease for x = 0:10. Evidence of host lattice as well as interstitial addition of Mg2+ ions has been realized for x = 0:10, through electron density analysis.
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de Francisco, Isabel, Jose Antonio Bea, Angel Vegas, Juan Bautista Carda et German Francisco de la Fuente. « In-situlaser synthesis of Nd–Al–O coatings : the role of sublattice cations in eutectic formation ». Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 71, no 1 (1 février 2015) : 95–111. http://dx.doi.org/10.1107/s2052520615000864.

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Neodymium aluminate coatings have been preparedin-situby the laser zone melting (LZM) method, using a CO2SLAB-type laser emitting at 10.6 µm. Polycrystalline Al2O3commercial plates have been used as substrates, and coatings were prepared from the corresponding mixtures of powdered neodymium and aluminium oxides as starting materials. Microstructure, studied by SEM and phase composition, studied by XRD, proved thein-situformation of a NdAlO3/NdAl11O18eutectic. As a result, a well integrated composite coating was formed. Nanoindentation tests are consistent with excellent integration between coating and substrate. Structural similarities between the eutectic components within the coating, as well as between these and the substrate, are consistent with the crystallographic concepts proposed by Vegas (Ramos-Gallardo & Vegas, 1997), where cation sub-arrays play an important role governing metal oxide structures. These structure sublattices are suggested as the driving force behind eutectic oxide formation.
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Nandi, Sanjoy Kumar, Sujan Kumar Das, Caleb Estherby, Angus Gentle et Robert G. Elliman. « Understanding modes of negative differential resistance in amorphous and polycrystalline vanadium oxides ». Journal of Applied Physics 128, no 24 (28 décembre 2020) : 244103. http://dx.doi.org/10.1063/5.0027875.

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Fu, C. M., C. J. Lai, H. S. Hsu, Y. C. Chao, J. C. A. Huang, C. C. Wu et S. G. Shyu. « Characterization of magnetoimpedance on polycrystalline and amorphous chromium oxides bilayered thin films ». Journal of Applied Physics 91, no 10 (2002) : 7143. http://dx.doi.org/10.1063/1.1455605.

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Napoli, Francesco, Mario Chiesa, Elio Giamello, Emanuele Finazzi, Cristiana Di Valentin et Gianfranco Pacchioni. « Partially Hydroxylated Polycrystalline Ionic Oxides : A New Route toward Electron-Rich Surfaces ». Journal of the American Chemical Society 129, no 34 (août 2007) : 10575–81. http://dx.doi.org/10.1021/ja073114k.

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Cabral, A. J. Freitas, C. M. R. Remédios, X. Gratens et V. A. Chitta. « Effects of microstructure on the magnetic properties of polycrystalline NiMn2O4 spinel oxides ». Journal of Magnetism and Magnetic Materials 469 (janvier 2019) : 108–12. http://dx.doi.org/10.1016/j.jmmm.2018.08.051.

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