نتایج جستجو برای: tetragonal phase
تعداد نتایج: 601737 فیلتر نتایج به سال:
The surface chemical properties of undoped tetragonal ZrO2 and the gas-phase dependence of the tetragonal-to-monoclinic transformation are studied using a tetragonal ZrO2 polymorph synthesized via a sol-gel method from an alkoxide precursor. The obtained phase-pure tetragonal ZrO2 is defective and strongly hydroxylated with pronounced Lewis acidic and Brønsted basic surface sites. Combined in s...
Obtaining the superconductor samples or mainly, structural phase controlling in 123 systems is a matter of special importance. As decreasing of oxygen in this structure has special effects, and mainly causing structural phase transition, by investigating the structure and thermal analysis of the system, tetragonal-orthorhombic structural phase transition was observed and optimum contents of s...
Full-perovskite Pb0.87Ba0.1La0.02(Zr0.6Sn0.33Ti0.07)O3 (PBLZST) thin films were fabricated by a sol-gel method. These revealed both rhombohedral and tetragonal phases, as opposed to the full-tetragonal phase previously reported in ceramics. The fractions of tetragonal and rhombohedral phases are found to be strongly dependent on film thickness. The fraction of tetragonal grains increases with i...
In this article, we have employed GSAS software to do Reitveld profile refinement on XRD patterns from H-Tc superconductor powder YBa2-xKxCu3O7-y (0<x,y<1) samples. Increasing the Potassium doping content of the sample, x, causes some changes in the XRD patterns such as creating new peaks and also deteriorating of goodness of the refinement, χ2. On the other hand, substituting of K instead of B...
In this study, the effect of different amounts of Y2O3 on the properties of mullite-zirconia composites was investigated. For this purpose, these composites were fabricated by reaction-sintering of alumina and zircon as raw materials. Besides, the slip casting method was used for forming these composites, and sintering process was carried out at 1600 °C. Then, the physical and mechanical pro...
The static and the dynamic spin correlations in the low-temperature collapsed tetragonal and the hightemperature tetragonal phase in CaFe2As2 have been investigated by As75 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. Through the temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts, although stripe-type ant...
As was shown in the past by XRD, TEM and RBS measurements, heavy ion irradiation of nanocrystalline ZrO2 samples using 4 MeV Kr + ions causes the formation of a tetragonal zirconia phase that is stable at room temperature [1]. This phase is employed in solid oxide fuel cells and oxygen sensors, but usually has to be stabilized by addition of a second phase, e.g. Y2O3, which is not necessary whe...
In this research Bi2O3 was doped with mixtures of 8, 10, 12 and 18 mol % of Y2O3 and Yb2O3 to stabilizing the δ-Bi2O3 phase using solid state reaction technique. Experimental samples were fabricated by isostatic pressing and sintering at 850 °C for 24 h. X-ray diffraction analysis detected cubic phase (δ-Bi2O3) as the sole stable crystalline phase in samples including 12 and 18 mol % of Y2O3 an...
We have used GSAS package for Reitveld analysis of XRD data from H-Tc superconductor powder YBa2-xKxCu3O7-y (0<1) samples. The procedure of Potassium doping, x, results in some residual impurities in the sample and so few extra peaks in the XRD patterns would appeared. On the other hand, substituting K by Ba causes, to some extent, oxygen depletion and also the lowering of the Ba (K) plane po...
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