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Journal articles on the topic 'Zirconium oxide – Defects'

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Published: 4 June 2021
Last updated: 18 February 2022

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1

Dunyushkina, Liliya, Adelya Khaliullina, Anastasia Meshcherskikh, Alexander Pankratov, and Denis Osinkin. "Effect of A-Site Nonstoichiometry on Defect Chemistry and Electrical Conductivity of Undoped and Y-Doped SrZrO3." Materials 12, no. 8 (April 17, 2019): 1258. http://dx.doi.org/10.3390/ma12081258.

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The effect of Sr-nonstoichiometry on phase composition, microstructure, defect chemistry and electrical conductivity of SrxZrO3−δ and SrxZr0.95Y0.05O3−δ ceramics (SZx and SZYx, respectively; x = 0.94–1.02) was investigated via X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and impedance spectroscopy followed by distribution of relaxation times analysis of impedance data. It was shown that at low Sr deficiency (x > 0.96 and 0.98 for SZx and SZYx, respectively) a solid solution of strontium vacancies in strontium zirconate crystal structure forms, whereas at higher Sr deficiency the secondary phase, zirconium oxide or yttrium zirconium oxide, is precipitated. Yttrium solubility limit in strontium zirconate was found to be close to 2 mol%. Y-doped strontium zirconates possess up to two orders of magnitude higher total conductivity than SZx samples. A-site nonstoichiometry was shown to have a significant effect on the electrical conductivity of SZx and SZYx. The highest total and bulk conductivity were observed at x = 0.98 for both systems. Increasing the conductivity with a rise in humidity indicates that proton conduction appears in the oxides in wet conditions. A defect model based on consideration of different types of point defects, such as strontium vacancies, substitutional defects and oxygen vacancies, and assumption of Y ions partitioning over Zr and Sr sites was elaborated. The proposed model consistently describes the obtained data on conductivity.
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2

Oh, Jiwon, Giwon Seo, Jaehwan Kim, Seungmuk Bae, Jeong-Woo Park, and Jin-Ha Hwang. "Plasma-Enhanced Atomic Layer Deposition of Zirconium Oxide Thin Films and Its Application to Solid Oxide Fuel Cells." Coatings 11, no. 3 (March 22, 2021): 362. http://dx.doi.org/10.3390/coatings11030362.

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Zirconium oxides were deposited using plasma-enhanced atomic layer deposition (PEALD) involving (2-(N-methylamino)1-MethylEthyleneCyclopentadienyl)Bis(DiMethylAmino)Zr (abbreviated as CMEN-Zr) and oxygen plasma as zirconium and oxygen sources. The zirconium oxide thin films demonstrate temperature-independent growth rates per cycle of 0.94 A/cycle at 150–215 °C. The deposited ZrO2 thin films were characterized using numerous analytical tools, i.e., X-ray photoelectron spectroscopy for chemical bonding state and composition, X-ray diffraction for crystallinity, atomic force microscopy for surface morphology, field-emission scanning electron microscopy for cross-sectional analysis, spectroscopic ellipsometry and UV–visible spectrophotometry for optical characterization, capacitance–voltage measurements for dielectric constants and atomic defects, and current–voltage characteristics for electrical information. The insulating features of the crystalline and stoichiometric ZrO2 films were implemented in the anode composites to evaluate the influence of ALD-based nano-features on the electrochemical performance of solid oxide fuel cells, with the main emphasis on anode performance. The presence of nanomaterials on Ni/YSZ anode composites is analyzed to determine the negative effects on electrochemical performance and the degradation of cell performance of solid oxide fuel cells (SOFCs). The artificial design was proven to be effective in controlling the cell performance as long as proper material design was adopted in SOFC electrodes.
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3

Park, Areum, Pyungho Choi, Woojin Jeon, Donghyeon Lee, Donghee Choi, and Byoungdeog Choi. "Defect Analysis and Reliability Characteristics of (HfZrO4)1−x(SiO2)x High-κ Dielectrics." Journal of Nanoscience and Nanotechnology 20, no. 11 (November 1, 2020): 6718–22. http://dx.doi.org/10.1166/jnn.2020.18791.

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Hafnium zirconium silicon oxide ((HfZrO4)1−x(SiO2)x) materials were investigated through the defect analysis and reliability characterization for next generation high-κ dielectric. Silicate doped hafnium zirconium oxide (HfZrO4) films showed a reduction of negative flat-band voltage (Vfb) shift compared to pure HfZrO4. This result was caused by a decrease in donor-like interface traps (Dit) and positive border traps (Nbt). As the silicon oxide (SiO2) content increased, the Vfb was shifted in the positive direction from −1.23 to −1.10 to −0.91 V and the slope of the capacitance–voltage (C–V) curve increased. The nonparallel shift of the C–V characteristics was affected by the Dit, while the Nbt was responsible for the parallel C–V curve shift. The values of Dit reduced from 4.3 × 1011, 3.5 × 1011, and 3.0 × 1011 cm−2eV−1, as well as the values of Nbt were decreased from 5.24, 3.90 to 2.26 × 1012 cm−2. Finally, reduction of defects in the HfZrO4-base film with an addition of SiO2 affected the gate oxide reliability characteristics, such as gate leakage current (JG), bias temperature stress instability (BTSI), and time dependent gate dielectric breakdown (TDDB).
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4

Sousa, W. S. C. de, D. M. A. Melo, J. E. C. da Silva, R. S. Nasar, M. C. Nasar, and J. A. Varela. "Photoluminescence in ZrO2 doped with Y and La." Cerâmica 53, no. 325 (March 2007): 99–103. http://dx.doi.org/10.1590/s0366-69132007000100015.

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This study aims to describe the synthesis and optical characterization of a nanometric zirconium oxide solid solution containing yttrium and lanthanum. Zirconium citrate, yttrium nitrate and lanthanum nitrate were mixed in the ratios: 94 mol% of ZrO2 - 6 mol% of Y2O3 and 92 mol% of ZrO2 - 6 mol % of Y2O3 - 2 mol % of La2O3. FTIR analysis shows organic material in decomposition and thermal analysis shows the transformation from the tetragonal to the monoclinic phase of zirconia, the loss of water molecule and zirconium dehydroxylation. The X-ray diffraction analysis shows a homogeneous phase formation of ZrO2-Y2O3-La2O3 demonstrating that lanthanum addition does not cause phase formation, promoting a solid solution based on zirconia with cubic structure. The photoluminescence spectra show absorption bands at 562 nm and 572 nm (350 °C) and specific absorption bands at 543 nm, 561 nm, 614 nm and 641 nm (900 °C). The photoluminescence effect at low temperature is caused by defects such as (Y Zr,Y O)', (2Y Zr,V O)'' and V O. Emissions at 614 nm and 641 nm are caused by O-2p -> Zr-4d transition. An emission at 543 nm can be attributed to LaO8 centers with O-2p -> La-5d transition.
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5

Volodin, Alexander M., Vladimir O. Stoyanovskii, Vladimir I. Zaykovskii, Roman M. Kenzhin, and Aleksey A. Vedyagin. "The Features of a High-Temperature Synthesis of ZrO2 in a Core-Shell ZrO2@C Structure." Materials Science Forum 950 (April 2019): 133–37. http://dx.doi.org/10.4028/www.scientific.net/msf.950.133.

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Zirconium oxide was obtained via traditional precipitation from a ZrOCl2 solution with ammonia followed by drying at 110 °C. The carbon-coated samples were synthesized by calcination of the pristine zirconia mixed with polyvinylalcohol. The obtained ZrO2@C samples of core-shell structure as well as the reference samples of pristine zirconia were calcined at different temperatures from 500 to 1400 °C. All the materials were examined by a set of physicochemical methods (a low-temperature argon adsorption, transmission electron microscopy, X-ray diffraction analysis, photoluminescence spectroscopy). It was found that the carbon coating prevents the sintering of the oxide nanoparticles, which allows one to maintain the specific surface area, the size of the oxide core and, finally, stabilize its phase composition. Transformation of the cubic phase into monoclinic phase becomes significantly complicated. Thus, 40% of the cubic phase was detected even after calcination of the ZrO2@C sample at 1400 °C. Moreover, the carbon-coated samples treated at elevated temperatures with subsequent removal of the carbon shell were found to possess the highest concentration of the defects related to a presence of the anion vacancies in zirconia.
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6

Tsuchiya, Bun, S. Nagata, Kesami Saito, Kentaro Toh, and Tadaaki Shikama. "Electrical Property of Calcium-Zirconium-Indium Oxide by Irradiation." Materials Science Forum 480-481 (March 2005): 579–84. http://dx.doi.org/10.4028/www.scientific.net/msf.480-481.579.

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Radiation induced changes in electrical properties of calcium-zirconium-indium oxide ceramics (CaZr0.9In0.1O3-d) were investigated using a fission reactor of Japan Materials Testing Reactor (JMTR). Electrical conductivity of CaZr0.9In0.1O3-d under the reactor irradiation increased by the Radiation Induced Conductivity (RIC), Radiation Induced Electromotive Force (RIEMIF)and Radiation Induced Electrical Degradation (RIED), caused by the electronic excitation. The RIC and the RIEMF decreased gradually for the constant value of the reactor power with the increase of irradiation time. Moreover, it was confirmed by Post-irradiation Examination (PIE) experiments that the initial electrical and thermal properties were completely degraded by the irradiation. These radiation effects are attributed to point defects or their clusters produced by atomic displacements caused by neutron collisions and also by the radiolysis.
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7

Zhang, Lina, Liang-Yu Chen, Cuihua Zhao, Yujing Liu, and Lai-Chang Zhang. "Calculation of Oxygen Diffusion Coefficients in Oxide Films Formed on Low-Temperature Annealed Zr Alloys and Their Related Corrosion Behavior." Metals 9, no. 8 (August 2, 2019): 850. http://dx.doi.org/10.3390/met9080850.

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The growth of oxide film, which results from the inward oxygen diffusion from a corrosive environment, is a critical consideration for the corrosion resistance of zirconium alloys. This work calculates the oxygen diffusion coefficients in the oxide films formed on zirconium alloys annealed at 400~500 °C and investigates the related corrosion behavior. The annealed samples have a close size for the second-phase particles but a distinctive hardness, indicating the difference in substrate conditions. The weight gain of all samples highly follows parabolic laws. The weight gain of the sample annealed at 400 °C has the fastest increase rate at the very beginning of the corrosion test, but its oxide film has the slowest growth rate as the corrosion proceeds. By contrast, the sample annealed at 500 °C shows the lowest weight gain but the highest corrosion rate constant. Such a corrosion behavior is attributed to the amount of defects existing in the oxide film formed on the annealed samples; fewer defects would provide a lower fraction of short-circuit diffusion in total diffusion, resulting in a lower diffusion coefficient of oxygen in the oxide film, thereby producing better corrosion resistance. This is consistent with the calculated diffusion coefficients of oxygen in the oxide films: 3.252 × 10−11 cm2/s, 3.464 × 10−11 cm2/s and 3.740 × 10−11 cm2/s for the samples annealed at 400 °C, 450 °C, and 500 °C, respectively.
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8

Raza, Mohsin, Simone Sanna, Lucia dos Santos Gómez, Eric Gautron, Abdel Aziz El Mel, Nini Pryds, Rony Snyders, Stéphanos Konstantinidis, and Vincenzo Esposito. "Near interface ionic transport in oxygen vacancy stabilized cubic zirconium oxide thin films." Physical Chemistry Chemical Physics 20, no. 41 (2018): 26068–71. http://dx.doi.org/10.1039/c8cp05465g.

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9

Terada, Yayoi, and Tetsuo Mohri. "Oxygen Migration and Local Structural Changes with Schottky Defects in Pure Zirconium Oxide Crystals." Journal of the Physical Society of Japan 87, no. 5 (May 15, 2018): 054801. http://dx.doi.org/10.7566/jpsj.87.054801.

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10

Ovsyannikov, Boris V. "Beware of Grain Refinement." Materials Science Forum 794-796 (June 2014): 143–48. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.143.

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Recently significant successes have been achieved in the field of grain refinement by means of such additives as the titanium, zirconium, scandium, AlTiB and AlTiC. However, introduction of grain refining additives results to a number of negative effects. These effects can be divided into four basic groups: 1. Reduction of high-strength alloy casting properties. 2. Defects of structure. 3. Intermetallic and oxide inclusions. 4. Decrease in mechanical and fatigue properties of the semis made of ingots with fine grain.
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11

Ivanovskaya, M. I., and E. V. Frolova. "Nature and conditions of formation of structural defects in zirconium(IV) oxide in the course of its preparation from zirconium hydroxide." Russian Journal of General Chemistry 77, no. 4 (April 2007): 524–31. http://dx.doi.org/10.1134/s1070363207040056.

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12

Liang, Zhihao, Shangxiong Zhou, Wei Cai, Xiao Fu, Honglong Ning, Junlong Chen, Weijian Yuan, Zhennan Zhu, Rihui Yao, and Junbiao Peng. "Zirconium-Aluminum-Oxide Dielectric Layer with High Dielectric and Relatively Low Leakage Prepared by Spin-Coating and the Application in Thin-Film Transistor." Coatings 10, no. 3 (March 18, 2020): 282. http://dx.doi.org/10.3390/coatings10030282.

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In this paper, zirconium–aluminum–oxide (ZAO) dielectric layers were prepared by a solution method with intent to combine the high dielectric constant with a low leakage current density. As a result, dielectric layers with improved electrical properties as expected can be obtained by spin-coating the mixed precursor. The chemical and physical properties of the films were measured by thermogravimetric differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and a UV spectrometer. It is observed that the oxygen defects and the hydroxide in the films are reduced with the addition of high-bond-energy zirconia, while the films can remain large optical bond gaps thanks to the presence of alumina. The metal-insulator-metal (MIM) devices were fabricated, and it was seen that with a molar ratio of Zr:Al = 3:1 and an annealing temperature of 500 °C, the dielectric layer afforded the highest dielectric constant of 21.1, as well as a relatively low leakage current of 2.5 10−6 A/cm2@1MV/cm. Furthermore, the indium–gallium–zinc oxide thin-film transistors (IGZO-TFTs) with an optimal ZAO dielectric layer were prepared by the solution method and a mobility of 14.89 cm2/Vs, and a threshold voltage swing of 0.11 V/dec and a 6.1 106 on/off ratio were achieved at an annealing temperature of 500 °C.
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13

Pettman, Ray, and Susan Okerstrom. "SEM evaluation of pacemaker surface processing." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 472–73. http://dx.doi.org/10.1017/s0424820100170098.

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Surface condition is critical for pacemakers (fig. 1) and other implanted biomedical devices. The surface must be cleanable, sterilizable, non-irritating to tissues, and have a good cosmetic appearance. Pure titanium is used for the pacemaker shields to enclose the circuitry. Current techniques for finishing the shields center around bright mill rolling and subsequent straight line finishing (SLF) or buffing. Small defects are magnified during buffing while SLF (fig. 2) fractures and galls the surface.A study was done to optimize surface finishing of pacemakers. Early efforts utilized three grits in a sandblasting technique. They were aluminum oxide ( A12O3), figure 3, zirconium oxide (ZrO2), figure 4, and silicon oxide (SiO2), figure 5. Standard light microscopy was employed to assess these first attempts. The resulting surfaces from the blasting mediums looked very similar. Standard light microscopy lacked the depth of field, magnification and resolution to adequately perform this analysis. Scanning electron microscopy (SEM) showed greater differences between the surface treatments.
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14

Martyushev, Nikita, Ilya V. Semenkov, and Yuriy N. Petrenko. "Impact of Protective Release Coatings with Nanopowders on the Quality of Bronze Castings Surface." Advanced Materials Research 872 (December 2013): 112–17. http://dx.doi.org/10.4028/www.scientific.net/amr.872.112.

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In work are submitted data of casting mold coverings with nanopowders application for molding lead bronze. Influence of a structure of used protective - separating coating of a foundry core on a microstructure of castings was investigated. For experimental work following coverings (the patent No 2297300) a mix dioxide zirconium nanopowder with industrial oil, and the same structure, but already on a basis on oxide aluminum nanopowder have been chosen. It is shown that these coverings application leads to decrease in quantity of surface defects, the roughness of a cast surface decreases. At the same time penetration of particles of a powder from a foundry covering in casting doesn't occur.
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15

Verma, Dinesh, Nivedita Shukla, Bharat Kumar, Alok Singh, Kavita Shahu, Mithilesh Yadav, Kyong Rhee, and Rashmi Rastogi. "Synergistic Tribo-Activity of Nanohybrids of Zirconia/Cerium-Doped Zirconia Nanoparticles with Nano Lamellar Reduced Graphene Oxide and Molybdenum Disulfide." Nanomaterials 10, no. 4 (April 8, 2020): 707. http://dx.doi.org/10.3390/nano10040707.

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Zirconia and 10%, 20%, and 30% cerium-doped zirconia nanoparticles (ZCO), ZCO-1, ZCO-2, and ZCO-3, respectively, were prepared using auto-combustion method. Binary nanohybrids, ZrO2@rGO and ZCO-2@rGO (rGO = reduced graphene oxide), and ternary nanohybrids, ZrO2@rGO@MoS2 and ZCO-2@rGO@MoS2, have been prepared with an anticipation of a fruitful synergic effect of rGO, MoS2, and cerium-doped zirconia on the tribo-activity. Tribo-activity of these additives in paraffin oil (PO) has been assessed by a four-ball lubricant tester at the optimized concentration, 0.125% w/v. The tribo-performance follows the order: ZCO-2@rGO@MoS2 > ZrO2@rGO@MoS2 > ZCO-2@rGO > ZrO2@rGO > MoS2 > ZrO2 > rGO > PO. The nanoparticles acting as spacers control restacking of the nanosheets provided structural augmentation while nanosheets, in turn, prevent agglomeration of the nanoparticles. Doped nanoparticles upgraded the activity by forming defects. Thus, the results acknowledge the synergic effect of cerium-doped zirconia and lamellar nanosheets of rGO and MoS2. There is noncovalent interaction among all the individuals. Analysis of the morphological features of wear-track carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM) in PO and its formulations with various additives is consistent with the above sequence. The energy dispersive X-ray (EDX) spectrum of ZCO-2@rGO@MoS2 indicates the existence of zirconium, cerium, molybdenum, and sulfur on the wear-track, confirming, thereby, the active role played by these elements during tribofilm formation. The X-ray photoelectron spectroscopy (XPS) studies of worn surface reveal that the tribofilm is made up of rGO, zirconia, ceria, and MoS2 along with Fe2O3, MoO3, and SO42− as the outcome of the tribo-chemical reaction.
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16

Martyushev, N. V., and E. N. Pashkov. "Bronze Sealing Rings Defects and Ways of its Elimination." Applied Mechanics and Materials 379 (August 2013): 82–86. http://dx.doi.org/10.4028/www.scientific.net/amm.379.82.

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In the article data about application nanopowder on a structure of coatings of the form are submitted at a casting of lead-tin bronzes. Elimination of gas porosity on a surface bronze cast preparations of high pressure compressors piston rings was the primary goal of such application protectively-dividing coverings. For experimental works mark of multicomponent bronze has been chosen. Its structure includes tin, lead, zinc and nickel. Casting from this bronze received a method of centrifugal molding. Influence of a structure of used protective - separating coating of a foundry core on a surface smoothness was probeed. Was compared action of coatings of a following composition: anti-burning-in coating (a blend of a low dispersible powder of chromium oxide with calcinated vegetable oil); anti-burning-in material ASPF-2/RgU (on the basis a low dispersible powder of graphite and the calcinated vegetable oil); the patent № 2297300 (blend of a ultradispersible powder of dioxide of zirconium with inpowderrial oil. Molding without use of coverings leads porosity depth to 4-5 mm and to a marriage significant amount (to 50 %). Use ASPF-2/RgU completely eliminates welding casting to a casting mold, but porosity on a surface remains. Application of coverings of a casting mold containing in quality of a filler ultradisperse powders oxide metals with low heat conductivity allows in to lower much a roughness and to eliminate gas porosity on a cast surface from lead-tin bronze. A gas time of a surface still remains, but them becomes much less and their form changes. Depth of defects doesn't exceed 1-1,5 mm that doesn't fall outside the limits the admission.
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17

Attarzadeh, Navid, and Chintalapalle V. Ramana. "Plasma Electrolytic Oxidation Ceramic Coatings on Zirconium (Zr) and ZrAlloys: Part I—Growth Mechanisms, Microstructure, and Chemical Composition." Coatings 11, no. 6 (May 25, 2021): 634. http://dx.doi.org/10.3390/coatings11060634.

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Recently, a significant number of research projects have been directed towards designing and developing ceramic coatings for zirconium-based substrates due to their outstanding surface properties and utilization in modern technologies. The plasma electrolytic oxidation (PEO) coating is an environmentally friendly wet coating method that can be performed in a wide range of electrolytes. The surface characteristics of PEO coatings can be tailored by changing electrochemical parameters, electrolyte composition, and substrate alloying elements to adopt a conformal and adhesive PEO ceramic coating for the final demanding applications in chemical, electronics, and energy technologies. This review focuses on deriving a deeper fundamental understanding of the PEO growth mechanisms and the effect of process parameters on transient discharge behavior at breakdown, initiation, and growth of the oxide layer and incorporating species from the electrolyte. It highlights the fundamental microstructural properties associated with structural defects, phase transformation, and the role of additives.
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18

Takeuchi, K., S. S. Perry, M. Salmeron, and G. A. Somorjai. "The bonding properties of hydrogenated and fluorinated molecules to zirconium oxide thin films: influence of surface defects and water coadsorption." Surface Science 323, no. 1-2 (January 1995): 30–38. http://dx.doi.org/10.1016/0039-6028(94)00621-0.

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19

Martyushev, Nikita V., and Nikolay A. Risto. "Effect of protective release coatings on the basis of superdispersersed zirconium oxide powder on the formation of gas defects in bronze casting." IOP Conference Series: Materials Science and Engineering 66 (October 7, 2014): 012013. http://dx.doi.org/10.1088/1757-899x/66/1/012013.

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20

Warcholiński, Bogdan, Adam Gilewicz, Alexandr S. Kuprin, Valeriy D. Ovcharenko, Roman Jędrzejewski, and Tatyana A. Kuznetsova. "Structure and morphology of Zr-O-N coatings formed by the method of cathodic arc evaporation." Inżynieria Powierzchni 23, no. 2 (August 16, 2018): 17–23. http://dx.doi.org/10.5604/01.3001.0012.2090.

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Oxynitrides of transitional metals are a coating material with decorative features due to the possibility of their adjustable colouring and good mechanical properties. The coatings of zirconium oxynitride have been deposited by the method of cathodic arc evaporation onto steel substrates. A set of coatings obtained at different relative volumetric concentrations of oxygen in the reaction atmosphere during deposition has been investigated. The influence of oxygen concentration on the colour, surface morphology and phase composition of the coatings has been analyzed. With the increase of oxygen content, the colour of the thin Zr-O-N coating has changed from golden-yellow to graphite. Observation of the surface of the coatings by means of the SEM method has shown the presence of surface defects in the form of macroparticles ranging from a submicron to several micrometers, with the smallest microparticle population being the largest. It has also been found that the surface roughness of the Zr-O-N coatings increases as the relative volumetric concentration of oxygen in the atmosphere during deposition increases. By means of X-ray diffraction analysis it has been shown that the zirconium oxide phase has occurred with a relative oxygen concentration of 50%, whereas below this value only the ZrN phase has been observed. The value of the parameter of the regular elementary cell of the Zr-O-N coatings increases as the relative concentration of oxygen in the atmosphere increases, while at the same time the intensity of the diffraction lines of the coatings decreases.
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21

Tang, W. M., M. G. Helander, M. T. Greiner, Z. H. Lu, and W. T. Ng. "Effects of Annealing Time on the Performance of OTFT on Glass with ZrO2as Gate Dielectric." Active and Passive Electronic Components 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/901076.

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Copper phthalocyanine-based organic thin-film transistors (OTFTs) with zirconium oxide (ZrO2) as gate dielectric have been fabricated on glass substrates. The gate dielectric is annealed in N2at different durations (5, 15, 40, and 60 min) to investigate the effects of annealing time on the electrical properties of the OTFTs. Experimental results show that the longer the annealing time for the OTFT, the better the performance. Among the devices studied, OTFTs with gate dielectric annealed at 350°C in N2for 60 min exhibit the best device performance. They have a small threshold voltage of −0.58 V, a low subthreshold slope of 0.8 V/decade, and a low off-state current of 0.73 nA. These characteristics demonstrate that the fabricated device is suitable for low-voltage and low-power operations. When compared with the TFT samples annealed for 5 min, the ones annealed for 60 min have 20% higher mobility and nearly two times smaller the subthreshold slope and off-state current. The extended annealing can effectively reduce the defects in the high-k film and produces a better insulator/organic interface. This results in lower amount of carrier scattering and larger CuPc grains for carrier transport.
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22

Sharma, Renu. "HREM studies of structure, defects and phase transformation in zirconia and Mn stabilised zirconia." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 824–25. http://dx.doi.org/10.1017/s0424820100177258.

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Zirconia is known to exist in three different structure types: monoclinic, tetragonal and cubic. Monoclinic is the room temperature form that transforms to tetragonal and finally to cubic at progressively higher temperatures. The monoclinic to tetragonal transformation is reversible, exhibits hysteresis and has been widely studied by thermal analysis, high temperature x-ray diffraction and electron diffraction. This transformation has an undesirable effect on some materials properties. The cubic form of zirconia has been stabilised with yttria, calcia, alumina and magnesia. The decomposition of zirconium carbonate and zirconium manganese carbonate to the respective oxides and their phase tranformation has been studied in situ by electron diffraction and high resolution electron microscopy (HREM) and the results are reported here.The carbonates used in these studies were precipitated from their aqueous solution. Thin crystal fragment were dispersed on holey carbon grids using a suspension in ethanol. A JE0L 4000EX microscope, with double tilt goniometer and on-line Digital MicroVAX II image-analysis system, operating at 400KV, was used for HREM studies.
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23

Kurita, Noriaki, Kenji Kobayashi, Yoshinori Heda, and Norihiko Fukatsu. "Oxygen Liberation from Stabilized Zirconia upon Changing DC Polarization Condition." High Temperature Materials and Processes 31, no. 4-5 (October 30, 2012): 439–49. http://dx.doi.org/10.1515/htmp-2012-0079.

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AbstractThe compositional change of stabilized zirconia upon the change of oxygen chemical potential was studied by applying DC-polarization method to a galvanic cell using stabilized zirconia as the electrolyte. The flow of excess charge observed upon the change of the DC-polarization condition was found due to the oxygen liberation from the bulk of the electrolyte. The total amount of liberated oxygen determined by the excess charge was analyzed in terms of the compositional change of the electrolyte due to the change of oxygen chemical potential profile in the electrolyte. The calculated values based on the increase or decrease of the electronic defects could not account for the experimental values. However, the ones based on the reduction of impurity oxides were in good agreement with the experimental values. Considerable amount of oxygen can be released from or absorbed into the zirconia electrolyte by the redox reaction of impurity oxide. It is noteworthy that this phenomenon may cause serious errors to the transport properties of electronic defect determined with the use of the relaxation processes.
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24

Zhu, Jiaxin, Jung-Woo Lee, Hyungwoo Lee, Lin Xie, Xiaoqing Pan, Roger A. De Souza, Chang-Beom Eom, and Stephen S. Nonnenmann. "Probing vacancy behavior across complex oxide heterointerfaces." Science Advances 5, no. 2 (February 2019): eaau8467. http://dx.doi.org/10.1126/sciadv.aau8467.

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Oxygen vacancies (VO••) play a critical role as defects in complex oxides in establishing functionality in systems including memristors, all-oxide electronics, and electrochemical cells that comprise metal-insulator-metal or complex oxide heterostructure configurations. Improving oxide-oxide interfaces necessitates a direct, spatial understanding of vacancy distributions that define electrochemically active regions. We show vacancies deplete over micrometer-level distances in Nb-doped SrTiO3 (Nb:SrTiO3) substrates due to deposition and post-annealing processes. We convert the surface potential across a strontium titanate/yttria-stabilized zirconia (STO/YSZ) heterostructured film to spatial (<100 nm) vacancy profiles within STO using (T = 500°C) in situ scanning probes and semiconductor analysis. Oxygen scavenging occurring during pulsed laser deposition reduces Nb:STO substantially, which partially reoxidizes in an oxygen-rich environment upon cooling. These results (i) introduce the means to spatially resolve quantitative vacancy distributions across oxide films and (ii) indicate the mechanisms by which oxide thin films enhance and then deplete vacancies within the underlying substrate.
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25

Kuriplach, Jan, O. Melikhova, Jakub Čížek, I. Procházka, G. Brauer, and W. Anwand. "Positron Annihilation at Planar Defects in Oxides." Materials Science Forum 733 (November 2012): 240–44. http://dx.doi.org/10.4028/www.scientific.net/msf.733.240.

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Planar defects may exhibit free volumes which, in principle, are detectable using positron annihilation spectroscopy. In this contribution, we present a preliminary theoretical study of positron trapping at stacking faults in zinc oxide and at a grain boundary in zirconia. In particular, we calculate the positron lifetime and positron binding energy to such defects. In the case of the grain boundary in zirconia, the influence of the yttrium segregation on the GB structure and positron characteristics is also examined. Calculated structural and positron characteristics are critically compared with experimental and other calculated data.
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26

Shah, Parag M., Joseph W. H. Burnett, David J. Morgan, Thomas E. Davies, and Stuart H. Taylor. "Ceria–Zirconia Mixed Metal Oxides Prepared via Mechanochemical Grinding of Carbonates for the Total Oxidation of Propane and Naphthalene." Catalysts 9, no. 5 (May 22, 2019): 475. http://dx.doi.org/10.3390/catal9050475.

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A series of ceria–zirconia mixed metal oxides with varying metal ratios were prepared by the calcination of precursors synthesized by mechanochemical grinding of the metal carbonates, and tested for catalytic naphthalene and propane total combustion. The mechanically-mixed metal oxides were more active for both propane and naphthalene total oxidation compared to the parent metal oxides. Ce0.95Zr0.05Ox was the most active catalyst for the total combustion of propane and naphthalene. Catalysts were characterized by x-ray diffraction, BET surface area, laser Raman spectroscopy, temperature programmed reduction, scanning electron microscopy with energy dispersive x-ray analysis and x-ray photoelectron spectroscopy techniques. Formation of ceria–zirconia solid solutions was observed for catalysts with a zirconia content of 10% or lower, whereas ceria and zirconia phase separation was observed when zirconia content was above 25%. Surface area increased when ceria and zirconia were mixed, and the reduction temperature of the bulk shifted to lower temperatures upon increasing zirconia content. Incorporation of zirconia was found to increase the relative concentration of surface oxygen defects compared to pure ceria, with low amounts of zirconia showing the greatest increase. The concentration of oxygen defects correlates with propane and naphthalene total oxidation activity. The enhanced total oxidation activity occurs as a result of the increased number of oxygen defects and the higher surface area. The results demonstrate that mechanochemical preparation from carbonate precursors was an effective route to make active catalysts.
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27

Hiraga, Keijiro, Byung Nam Kim, Koji Morita, Tohru Suzuki, and Yoshio Sakka. "Microstructural Design for Attaining High-Strain-Rate Superplasticity in Oxide Materials." Advances in Science and Technology 45 (October 2006): 923–32. http://dx.doi.org/10.4028/www.scientific.net/ast.45.923.

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Factors limiting the strain rate of superplastic deformation in oxide ceramics are discussed from existing knowledge about the mechanisms of high-temperature plastic deformation and intergranular cavitation. The discussion leads to the following guide: simultaneously controlling the initial grain size, diffusivity, dynamic grain growth, homogeneity of microstructure and the number of residual defects is essential to attain high-strain-rate superplasticity. Along this guide, high-strain-rate superplasticity (HSRS) is attainable in some oxides consisting of tetragonal zirconia, α-alumina and a spinel phase: tensile ductility reached 300-2500% at a strain rate of 0.01-1.0 s-1. Post-deformation microstructure indicates that some secondary phases may suppress cavitation damage and thereby enhance HSRS. The guide is also essential to lower the limit of deformation temperature for a given strain rate. In monolithic tetragonal zirconia, grain-size refinement combined with doping of aliovalnt cations such as Mg2+, Ti4+ and Al3+ led to HSRS at 1350 °C.
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Zhang, Jingying, Xiao Fu, Shangxiong Zhou, Honglong Ning, Yiping Wang, Dong Guo, Wei Cai, Zhihao Liang, Rihui Yao, and Junbiao Peng. "The Effect of Zirconium Doping on Solution-Processed Indium Oxide Thin Films Measured by a Novel Nondestructive Testing Method (Microwave Photoconductivity Decay)." Coatings 9, no. 7 (July 5, 2019): 426. http://dx.doi.org/10.3390/coatings9070426.

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Solution-processed indium oxide is an ideal transparent semiconductor material with wide band gap. Zirconium is an element characterized by a strong binding ability to oxygen which can inhibit the formation of oxygen vacancies and reduce the surface defect state. In this paper, zirconium doped indium oxide (InxZryO) thin films were prepared by the solution method, with indium oxide being doped with zirconium in order to tune the relative number of oxygen vacancies. The influence of the Zr doping concentration and the post-annealed temperature on the properties of the InxZryO thin films was investigated. The results show that the doping process improves the crystallinity and relative density of the obtained films. A novel nondestructive method named microwave photoconductivity decay (μ-PCD) was used to evaluate the quality of InxZryO thin films by simply measuring their response under laser irradiation. The relative number of oxygen vacancies and the minority carrier concentration achieved minimum values at 10 at.% Zr doping concentration. Furthermore, InxZryO thin films with optimal properties from an electrical point of view were obtained at 10 at.% Zr doping concentration, annealed at 400 °C. Characterized by an average transmittance above 90% in the visible range, the obtained InxZryO thin films can be used as active layer materials in the fabrication of high-performance thin film transistor (TFT) devices.
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29

Prochazka, I., J. Cizek, O. Melikhova, T. E. Konstantinova, and I. A. Danilenko. "Defects in Zirconia Nanomaterials Doped with Rare-Earth Oxides." Acta Physica Polonica A 125, no. 3 (March 2014): 760–63. http://dx.doi.org/10.12693/aphyspola.125.760.

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30

Schlexer, Philomena, Antonio Ruiz Puigdollers, and Gianfranco Pacchioni. "Tuning the charge state of Ag and Au atoms and clusters deposited on oxide surfaces by doping: a DFT study of the adsorption properties of nitrogen- and niobium-doped TiO2 and ZrO2." Physical Chemistry Chemical Physics 17, no. 34 (2015): 22342–60. http://dx.doi.org/10.1039/c5cp03834k.

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31

Petot-Ervas, Georgette, C. Petot, Jean Marc Raulot, and J. Kusinski. "Anionic and Cationic Diffusion in Ionic Conducting Oxides." Defect and Diffusion Forum 237-240 (April 2005): 843–48. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.843.

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This paper concerns an analysis of the transport processes at high temperature in anionic conducting oxides subjected to a chemical potential gradient or an applied electrical field. The general equations are given. The principle of the cationic kinetic demixing under a “generalized“ thermodynamical potential gradient is reviewed. Experimental results obtained with yttria-doped zirconia are reported. An experimental procedure for the determination of the oxygen diffusion coefficient in ionic and semiconducting oxides is also described. The results obtained with yttriastabilized zirconia are compared to both self diffusion and conductivity data. This has allowed us to obtain information concerning the defect structure.
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32

Kuroda, K., T. Yoshida, T. Murase, and H. Saka. "Extended defects in plastically deformed superconducting ceramics." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 40–41. http://dx.doi.org/10.1017/s0424820100173339.

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Extended defects introduced by high temperature deformation into high Tc superconducting ceramics have been characterized by means of transmission electron microscopy.Single crystals of YBa2Cu3O7−x (YBCO) were grown from melting mixtures of yttria, barium carbonate and copper oxide contained in alumina boats. Crystals having tetragonal symmetry grew as platelets with dimensions up to 10×10×0.1 mm3 and the (001) broad surface. Crystals were deformed by Brinell indentation with an indenter of Y-doped zirconia between 550 and 900 °C in air. Most indents were done with a load of 70 grf and a loading period of up to 24 h. Thin specimens were prepared by back-thinning technique using an Ar ion beam at 4 kV.Polycrystals of Bio. 8Pbo. 2SrCa1. 1Cu1. 6Ox (BSCCO) were prepared by sintering process. Rectangular specimens 3×3×8 mm were sectioned from the sintered materials. They were deformed in commpression at 800 °C using strain rate of 1.3×10−5 s−1. Specimens could be deformed to as large as 90 % in a nominal compressive strain.
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33

Parkes, Michael A., David A. Tompsett, Mayeul d'Avezac, Gregory J. Offer, Nigel P. Brandon, and Nicholas M. Harrison. "The atomistic structure of yttria stabilised zirconia at 6.7 mol%: an ab initio study." Physical Chemistry Chemical Physics 18, no. 45 (2016): 31277–85. http://dx.doi.org/10.1039/c6cp04694k.

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34

Jo, Minho, Jongsu Lee, Seongyong Kim, Gyoujin Cho, Taik-Min Lee, and Changwoo Lee. "Web Unevenness Due to Thermal Deformation in the Roll-to-Roll Manufacturing Process." Applied Sciences 10, no. 23 (December 2, 2020): 8636. http://dx.doi.org/10.3390/app10238636.

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In roll-to-roll (R2R) processing, web uniformity is a crucial factor that can guarantee high coating quality. To understand web defects due to thermal deformation, we analyzed the effect of web unevenness on the coating quality of an yttria-stabilized zirconia (YSZ) layer, a brittle electrolyte of solid oxide fuel cells (SOFCs). We used finite-element analysis to study thermal and mechanical deformations at different drying temperature levels. A YSZ layer was also coated using R2R slot-die coating to observe the effect of web unevenness on coating quality. Web unevenness was generated by thermal deformation due to conduction and convection heat from the dryer. Because of varying web unevenness with time, the YSZ layer developed cracks. At higher drying temperatures, more coating defects with larger widths were generated. Results indicated that web unevenness at the coating section led to coating defects that could damage the SOFCs and decrease yield in the R2R process. Coating defects generated by web unevenness caused by convection and conduction heat should be considered in the high-volume production of brittle electrolytes using the R2R process.
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35

Ojala, Satu, Tiina Laitinen, Sian Leneuf de Neufville, Mari Honkanen, Minnamari Vippola, Mika Huuhtanen, and Riitta L. Keiski. "Vanadia–Zirconia and Vanadia–Hafnia Catalysts for Utilization of Volatile Organic Compound Emissions." Materials 14, no. 18 (September 13, 2021): 5265. http://dx.doi.org/10.3390/ma14185265.

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Utilization is a sustainable and interesting alternative for the destructive treatment of volatile organic compounds due to avoided CO2 emission. This work concentrates on the development of active and sulfur-tolerant catalysts for the utilization of contaminated methanol. Impregnated and sol–gel prepared vanadia–zirconia and vanadia–hafnia catalysts were thoroughly characterized by N2 sorption, analytical (S)TEM, elemental analysis, XRD and Raman spectroscopy, and their performances were evaluated in formaldehyde production from methanol and methanethiol mixture. The results showed higher activity of the sol–gel prepared catalysts due to formation of mono- and polymeric vanadia species. Unfortunately, the most active vanadia sites were deactivated more easily than the metal-mixed oxide HfV2O7 and ZrV2O7 phases, as well as crystalline V2O5 observed in the impregnated catalysts. Metal-mixed oxide phases were formed in impregnated catalysts through formation of defects in HfO2 and ZrO2 structure during calcination at 600 °C, which was evidenced by Raman spectroscopy. The sol–gel prepared vanadia–zirconia and vanadia–hafnia catalysts were able to produce formaldehyde from contaminated methanol with high selectivity at temperature around 400 °C, while impregnated catalysts required 50–100 °C higher temperatures.
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36

Перевалов, T. B. "Моделирование атомной и электронной структуры вакансий и поливакансий кислорода в ZrO-=SUB=-2-=/SUB=-." Физика твердого тела 60, no. 3 (2018): 421. http://dx.doi.org/10.21883/ftt.2018.03.45537.03d.

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AbstractCubic, tetragonal, and monoclinic phases of zirconium oxide with oxygen vacancies and polyvacancies are studied by quantum chemical modeling of the atomic and electronic structure. It is demonstrated that an oxygen vacancy in ZrO_2 may act as both an electron trap and a hole one. An electron added to the ZrO_2 structure with an oxygen vacancy is distributed between two neighboring Zr atoms and is a bonding orbital by nature. It is advantageous for each subsequent O vacancy to form close to the already existing ones; notably, one Zr atom has no more than two removed O atoms related to it. Defect levels from oxygen polyvacancies are distributed in the bandgap with preferential localization in the vicinity of the oxygen monovacancy level.
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37

Yurchenko, Lesya P., Igor P. Bykov, Alexander B. Brik, Oleksandr D. Vasylyev, Valeriy G. Vereschak, Gunnar Suchaneck, Lubomir Jastrabik, and Alexandr Dejneka. "Defect Structure of Nanosized Zirconium Oxide Powders Doped with Y2O3, Sc2O3, Cr2O3." Solid State Phenomena 200 (April 2013): 108–13. http://dx.doi.org/10.4028/www.scientific.net/ssp.200.108.

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The formation mechanisms of paramagnetic centers originating from Zr3+ and Cr3+ ions and the influence of the nanoparticle composition on thermal generation processes of these paramagnetic centers in ZrO2 structure were studied by electron paramagnetic resonance. A set of nanosized zirconium oxide powders (nominally pure ZrO2, ZrO2 doped with correspondingly Y2O3 and Sc2O3, Cr2O3 and Y2O3, as well as Cr2O3) was investigated: The influence of annealing on the EPR lines of Zr3+ and Cr5+ ions was found to be different. Annealing curves of EPR signals caused by Cr5+ ions have a maximum in temperature range 500–600 °C. Mechanisms of Zr3+ and Cr5+ ions formation were discussed.
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38

Frolova, Elena V., and Mariya I. Ivanoskaya. "Structural Defect Formation in Inorganic Sol-Gel Derived Oxides." Defect and Diffusion Forum 242-244 (September 2005): 143–58. http://dx.doi.org/10.4028/www.scientific.net/ddf.242-244.143.

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The advantages and uniqueness of the Inorganic modification of the Sol-Gel method have already been described. Homogeneous nano-composites as well as some exotic glasses, complex-metal-oxides systems with little glass-forming ability, can be produced by this method. Thus, the obtained materials are characterized by a complex structure that leads to the wide variety of physical and chemical properties. Zirconia-containing materials are of utmost interest because of the mechanical toughness and chemical resistance provided by the presence of ZrO2. In the present work, we report on unusual structural peculiarities of the Zr-O, two types of Zr-Ge-O systems (with Zr>Ge and Zr<Ge molar ratios) and Zr-Ce-Al-O glassy samples, successfully prepared by inorganic modification of the Sol-Gel technique. We tried to elucidate the cause of a self-reduction process in those oxides systems under thermal treatment in air and the way in which structural imperfections impact upon some properties of the materials obtained.
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39

Yu, Qianran, Michael Reyes, Nachiket Shah, and Jaime Marian. "Kinetic Model of Incipient Hydride Formation in Zr Clad under Dynamic Oxide Growth Conditions." Materials 13, no. 5 (February 29, 2020): 1088. http://dx.doi.org/10.3390/ma13051088.

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The formation of elongated zirconium hydride platelets during corrosion of nuclear fuel clad is linked to its premature failure due to embrittlement and delayed hydride cracking. Despite their importance, however, most existing models of hydride nucleation and growth in Zr alloys are phenomenological and lack sufficient physical detail to become predictive under the variety of conditions found in nuclear reactors during operation. Moreover, most models ignore the dynamic nature of clad oxidation, which requires that hydrogen transport and precipitation be considered in a scenario where the oxide layer is continuously growing at the expense of the metal substrate. In this paper, we perform simulations of hydride formation in Zr clads with a moving oxide/metal boundary using a stochastic kinetic diffusion/reaction model parameterized with state-of-the-art defect and solute energetics. Our model uses the solutions of the hydrogen diffusion problem across an increasingly-coarse oxide layer to define boundary conditions for the kinetic simulations of hydrogen penetration, precipitation, and dissolution in the metal clad. Our method captures the spatial dependence of the problem by discretizing all spatial derivatives using a stochastic finite difference scheme. Our results include hydride number densities and size distributions along the radial coordinate of the clad for the first 1.6 h of evolution, providing a quantitative picture of hydride incipient nucleation and growth under clad service conditions.
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40

Hsu, Hsiao-Hsuan, Hsiu-Ming Liu, and Sheng Lee. "Experimental Investigation of Thermal Annealing and Ferroelectric Capacitor Area Effects for Hafnium-Zirconium Oxide Devices." Coatings 10, no. 8 (July 26, 2020): 733. http://dx.doi.org/10.3390/coatings10080733.

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In this study, we reveal that the thermal budget of post-metal annealing not only determines the formation of the ferroelectric phase and dipole domain but also the film quality of the gate stack in a metal-ferroelectric-metal capacitor. The higher leakage current caused by defect traps or grain boundaries within a gate stack would influence the stability of the ferroelectric domain switching. Furthermore, the ferroelectric domain switching and polarization current also depend on the ferroelectric capacitor area. We observe that a HfAlO ferroelectric capacitor can dominate the transfer characteristics of a p-type SnO thin-film transistor through the modulation of series capacitance in the gate stack based on a one-transistor one-capacitor series configuration. According to experimental results, the memory hysteresis window can be improved significantly with the area scaling due to the improvement of capacitance matching accuracy.
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41

Moreno, V., R. M. Bernardino, and D. Hotza. "Mechanical Behavior of Yttria-Stabilized Zirconia Aqueous Cast Tapes and Laminates." Journal of Ceramics 2014 (March 9, 2014): 1–5. http://dx.doi.org/10.1155/2014/713916.

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Aqueous tape casting was used to produce yttria-stabilized zirconia films for electrolyte-supported solid oxide fuel cell (SOFC). Tape casting slurries were prepared varying the binder content between 20 and 25 wt%. A commercial acrylic emulsion served as binder. Rheological measurements of the two slurries were performed. Both slurries showed a shear-thinning behavior. Tapes with 25 wt% binder exhibited adequate flexibility and a smooth and homogeneous surface, free of cracks and other defects. Suitable conditions of lamination were found and a theoretical density of 54% in the laminates was achieved. Laminated tapes showed higher tensile strength compared to single sheets. Tape orientation has a significant influence on the mechanical properties. Tensile strength, elongation to strain, and Young’s modulus measured in samples produced in the direction of casting showed higher property values.
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42

Porporati, Alessandro Alan, Maria Chiara Munisso, Kristina Lessnau, and Giuseppe Pezzotti. "Stoichiometry and Surface Stress Analyses in Advanced Alumina/Zirconia Composites for Hip Arthroplasty Applications." Advances in Science and Technology 76 (October 2010): 240–46. http://dx.doi.org/10.4028/www.scientific.net/ast.76.240.

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A spatially resolved cathodoluminescence (CL) analysis is used as a means for chemical and mechanical analyses of the composite surface after environmental exposure. CL emission proves extremely efficient in concurrently monitoring the concentration of point defects (e.g., oxygen vacancies) on the material surface. Using CL, averaging effects from sub-surface parts of the material can be minimized, and the actual chemical state of the material surface is revealed. As a result, information about the stoichiometry of the material surface can be obtained directly from the lattices of the constituent phases, this enabling one to pattern relevant connections to the environmental resistance of oxide-based bioceramics. A highly fracture resistant alumina/zirconia composite represents the latest trend in ceramics for arthroplastic applications in alternative to monolithic alumina or zirconia ceramics. This composite material is designed from both chemical and microstructural viewpoints in order to prevent environmental degradation and fracture events in vivo, an important step forward in the full exploitation of ceramic materials in the field of arthroplasty. Systematically monitoring the optical activity of oxygen vacancies in both alumina and zirconia phase reveals the distinct role on the kinetics of polymorphic transformation. From the presented data an explicit role is evinced for oxygen vacancy formation in the alumina matrix in the complex cascade of mechanochemical events determining the environmental resistance of the composite.
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43

Lokteva, Ekaterina S., and Elena V. Golubina. "Metal-support interactions in the design of heterogeneous catalysts for redox processes." Pure and Applied Chemistry 91, no. 4 (April 24, 2019): 609–31. http://dx.doi.org/10.1515/pac-2018-0715.

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Abstract The effect of the metal-support interaction (MSI) has been discussed for several types of catalytic systems comprising metal nanoparticles (Ni, Pd, Au, Fe) on oxide and carbon supports, showing promising catalytic properties in hydrogenation of unsaturated C–C bonds, hydrodechlorination (HDC) of chlorinated organic molecules and CO total oxidation. The MSI of a different strength, from the redistribution of the electron density of nanoparticles (NPs) to the chemical interactions, is determined by the composition of the support and the active site, the method of active metal deposition, calcination temperature, particle size etc. The types of MSI considered in this review include: (1) the interaction of the active metal (Me) NPs with alumina and modified zirconia to form several oxidation states of Me in the composition of surface or bulk chemical compounds with a support; (2) the influence of oxide (alumina, silica) or carbon (highly oriented pyrolytic graphite, Sibunit) supports on the formation of active sites in the catalysts with ultra-low Me loading prepared by deposition of pre-formed metal NPs produced by laser electrodispersion (LED) or as colloidal dispersion; (3) the anchoring of Me NPs on the surface of carbon supports (nanodiamonds and carbon nanotubes) directly with a support surface, e.g. through surface defects, or through surface functional groups; (4) ‘reverse’ MSI in the Me@C composites, consisting of metal NPs, covered with the defected graphene layers or immersed into carbon matrix. It is demonstrated on the example of LED systems, that oxidation of metal under MSI is less significant in carbon-supported systems than in oxide-supported ones, but charge effects can play a noticeable role for both types of supports. Different ways of MSI tuning provide the possibilities to achieve the optimal Men+/Me0 ratio in the catalysts for HDC of mono- and polychlorinated organic molecules, including persistent organic pollutants. One of these ways is tuning the composition of functional groups on the surface of nanodiamonds and carbon nanotubes by additional treatments to achieve the desirable metal anchoring, the optimal metal NPs size and the improved catalytic properties. Unusual type of MSI is represented by the activation of thin graphene shell of Me@C composites by the presence of defects in the shell and a transition metal (Ni, Fe) in subsurface layer. This effect allows H2 activation that is a significant step in many industrially important reactions. The selectivity and activity of such systems can be intentionally changed by varying the nature of metal and reaction temperature. Significant attention has been given in the review to the novel catalytic systems described in the previous works of the authors.
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44

Chen, Song, Yun Chen, Harry Finklea, Xueyan Song, Gregory Hackett, and Kirk Gerdes. "Crystal defects of yttria stabilized zirconia in Solid Oxide Fuel Cells and their evolution upon cell operation." Solid State Ionics 206 (January 2012): 104–11. http://dx.doi.org/10.1016/j.ssi.2011.11.008.

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45

Park, Tae-sung, Nana Kwabena Adomako, Andrews-nsiah Ashong, Young-kuk Kim, Seung-min Yang, and Jeoung-han Kim. "Interfacial Structure and Physical Properties of High-Entropy Oxide Coatings Prepared via Atmospheric Plasma Spraying." Coatings 11, no. 7 (June 24, 2021): 755. http://dx.doi.org/10.3390/coatings11070755.

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The feasibility of using a high-entropy rare-earth oxide (REO) as a top coating material for thermal barrier coatings was explored using the atmospheric plasma spray technique. The microstructure and Vickers hardness of the coating layer were compared to those of an 8 mol % yttria-stabilized zirconia (8YSZ) top coating material. Macroscopic observations revealed the formation of a well-coated surface with no surface defects or delamination. Scanning electron microscopy images showed the presence of several parallel and vertical microcracks in the REO and 8YSZ coating layers. The origin of these cracks is attributed to differences in the coefficient of thermal expansion, very fast cooling, and process parameters. X-ray diffraction demonstrated the high phase stability and excellent thermal properties of REO due to the absence of phase transformation after plasma spray processing. The measured Vickers hardness of REO was 425 HV, which is lower than that of sintered REO powder and the 8YSZ coating.
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46

Emeline, A., A. Salinaro, V. K. Ryabchuk, and N. Serpone. "Photo-induced processes in heterogeneous nanosystems. From photoexcitation to interfacial chemical transformations." International Journal of Photoenergy 3, no. 1 (2001): 1–16. http://dx.doi.org/10.1155/s1110662x01000010.

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This article briefly reviews some of our recent work carried out both from an experimental point of view as well as from a theoretical perspective to gain further understanding of the events that take place in Heterogeneous Photocatalysis. Previously, the multitude of reports from our laboratory and from many others looked at the primary photocatalytic events as involving (a) absorption of light, (b) formation of the free (electrons and holes) and/or trapped charge carriers (Ti3+and •OH radicals), and (c) reaction of pre-adsorbed acceptor or donor molecules with the relevant trapped carrier. Our recent work notes that this view is reasonable if the only purpose of photocatalysis is elimination of undesirable environmental pollutants. But when we begin to query how to render a process more efficient, we need to address the primary events following photoexcitation of the photocatalyst, which in most instances has been titanium dioxide (in the anatase form). Owing to the nature of light absorption byTiO2we resorted to examining other metal oxides, most of which are dielectric insulators with very large bandgap energies, for example zirconia (ZrO2) and scandia (Sc2O3). These dielectrics have provided added information on the photophysical events, many of which are masked by the strong light absorption in titania. Despite some of our recent progress, much remains to be done for a fuller understanding of the events that occur at the surface, which we have often considered to be the greatest and most complex defect in metal oxide particulates.
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47

Chen, Xiaoge, Hongsong Zhang, Longfei Zhou, Bo Ren, An Tang, and Xudan Dang. "Influence of Ti addition on thermophyscial properties of Sm2Ce2O7 oxides." Processing and Application of Ceramics 12, no. 1 (2018): 21–26. http://dx.doi.org/10.2298/pac1801021c.

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Sm2(Ce1-xTix)2O7 (where x = 0, 0.1,0.3, 0.5) solid solutions were synthesized by conventional solid state reaction method using Sm2O3, CeO2 and TiO2 as raw reactants. The synthesized powders were pressed into pellets by cold isostatic pressing and pressure-less sintered at 1600 ?C for ten hours. Their phase-structure and thermophysical properties were studied. The synthesized samples exhibit single defect fluorite-type structure. Due to the phonon scattering by substitutional atoms, the thermal conductivities of the Sm2(Ce1-xTix)2O7 solid solutions decrease with the increasing Ti4+ content over the entire temperature range, which are significantly lower than that of yttrium stabilized zirconia (YSZ). The thermal expansion coefficients of the prepared Sm2(Ce1-xTix)2O7 solid solutions also decrease with the increasing Ti4+ fraction, which can be attributed to the lower titanium ion radius.
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48

Nakamura, Akio, and J. Bruce Wagner. "Defect Structure, Ionic Conductivity, and Diffusion in Yttria Stabilized Zirconia and Related Oxide Electrolytes with Fluorite Structure." Journal of The Electrochemical Society 133, no. 8 (August 1, 1986): 1542–48. http://dx.doi.org/10.1149/1.2108965.

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49

Chen, Weiqun, Theresa A. Lee, and Alexandra Navrotsky. "Enthalpy of Formation of Yttria-Doped Ceria." Journal of Materials Research 20, no. 1 (January 2005): 144–50. http://dx.doi.org/10.1557/jmr.2005.0017.

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Solid solutions (1 − x)CeO2 − xYO1.5 (0 ≤ x ≤ 0.36) were prepared by coprecipitation and sol-gel methods. Their enthalpy of formation relative to the end-members, fluorite-type cubic CeO2 and C-type YO1.5 was determined by oxide melt solution calorimetry. The enthalpy of drop solution shows a roughly linear trend with composition. Extrapolation to x = 1 gives the transition enthalpy of C-type to cubic fluorite YO1.5 as 22.2 ± 6.7 kJ/mol. This linear behavior is in contrast to the strong curvature seen in the ZrO2 − YO1.5 and HfO2 − YO1.5 systems. The slightly positive enthalpy of formation of CeO2 − YO1.5 is strikingly different from the strongly negative enthalpies of formation of ZrO2 − YO1.5 and HfO2 − YO1.5. The thermodynamics of CeO2 − YO1.5 is analyzed in terms of defect association and oxygen vacancy distribution. Specifically, the association of oxygen vacancies with the tetravalent cations in the zirconia and hafnia systems, in contrast to the preference of vacancies for nearest neighbor yttrium sites in the ceria systems, may explain the different energetics.
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Nakamura, Akio, Nobuyuki Masaki, Haruyoshi Otobe, Yukio Hinatsu, Junhu Wang, and Masuo Takeda. "Defect-fluorite oxides M1-yLnyO2-y/2(Ln = lanthanide; M = Hf, Zr, Ce, U, Th): Structure, property, and applications." Pure and Applied Chemistry 79, no. 10 (January 1, 2007): 1691–729. http://dx.doi.org/10.1351/pac200779101691.

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Abstract:
An up-to-date summary of our coupled macroscopic (lattice parameter, a0) and microscopic (Mössbauer) studies on the entitled systems is given, shedding new light on the basic phase and structure properties of these technologically important, highly defective oxides. Through these studies, the intermediate-pyrochlore (P)-based local structure nature of the so-called stabilized-zirconia (SZ)- and stabilized-hafnia (SH)-type defect-fluorite (DF) phases in the M4+ = Zr and Hf systems seems to be almost unambiguously established with different (from the conventional) approaches: These are (1) the presence of a broad lattice parameter (a0) hump over the extended stabilized cubic DF region (y = ~0.3-~0.7); (2) the microscopic 151Eu-Mössbauer evidence of Eu3+ isomer shifts (ISs) showing characteristic V-shaped minima around the ideal-P area (y ~ 0.50) for both the M4+ = Zr and Hf systems; and (3) rich 155Gd-Mössbauer data on the Zr1-yGdyO2-y/2 system [IS, quadrupole splitting (QS), line width, peak height, and relative absorption area (RAA)], revealing detailed features of its ordered P-disordered DF phase and structure relationships. These results are discussed with reported basic-property data of these systems.
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