Results 1 - 10 of 9938
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[en] Although the Sr Ru O3 (SR) and Sr Ru O3 (SR) and Sr Hf O3 and Sr Hf O3 as other perovskite oxides, have been know for well over 30 years, their crystal structure are still not well established either at room temperature nor higher temperatures. We report the structure analysis by X-Ray diffraction and perturbed angular correlation measurements of SH and SR from room temperature to 1000 deg C. Both compound, SH and SR showed an orthorhombic Pnma symmetry at room temperature. At higher temperatures, the compounds undergo a phase transition from orthorhombic to cubic (Pm 3m) symmetry around 700 deg C. (author)
[en] We report the synthesis of Sr(sub 1-x)Ca(sub x)MnO(sub 3) and La(sub 0.5)Ba(sub 0.5)MnO(sub 3) perovskites over extended cation and oxygen composition ranges and describe the dependence of their phase stability on the tolerance factor t= t(x,T,(delta)) that is a function of composition, temperature, and oxygen content. We show that magnetic transition temperatures depend strongly on the tolerance factor and charge disorder while dependence on the structural disorder is less important. By reducing charge and structural disorder we have significantly increased the Curie and Neel temperatures for perovskite manganites
[en] The morphological and electrical properties of yttrium (Y) and indium (In) doped barium cerate perovskites of the form BaIn0.3-xYxCe0.7O3-δ (with x=0-0.3) prepared by a modified Pechini method were investigated as potential high temperature proton conductors with improved chemical stability. The sinterability increased with the increase of In-doping, and the perovskite phase was found in the BaIn0.3-xYxCe0.7O3-δ solid solutions over the range 0 (le) x (le) 0.3. The conductivities decreased (from x to x, insert quantitative values) while the tolerance to wet CO2 improved for BaIn0.3-xYxCe0.7O3-δ samples with an increase of In-doping.
[en] Inorganic lead halide perovskite nanocrystals (NCs) with superior photoelectric properties are expected to have excellent performance in many fields. However, the anion exchange changes their features and is unfavorable for their applications in many fields. Hence, impeding anion exchange is important for improving the composition stability of inorganic lead halide perovskite NCs. Herein, CsPbX 3 (X = Cl, Br) NCs are coated with Cs4PbX 6 shell to impede anion exchange and reduce anion mobility. The Cs4PbX 6 shell is facily fabricated on CsPbX 3 NCs through high temperature injection method. Anion exchange experiments demonstrate that the Cs4PbX 6 shell completely encapsulates CsPbX 3 NCs and greatly improves the composition stability of CsPbX 3 NCs. Moreover, our work also sheds light on the potential design approaches of various heterostructures to expand the application of CsPbM3 (M = Cl, Br, I) NCs. (paper)
[en] The effect of the support on the catalytic performance of Ni catalysts in carbon dioxide reforming of methane was studied using perovskite based supports BaTi 1x In x O 3d, known by their ionic and electronic conductivity properties. The results of the investigation showed that there is a close relationship between the catalytic activity and the reducibility of the support.
[en] Highlights: • Successful synthesis of LaAlO3 using starch. • LaAlO3 nucleation was identified within a mixed lanthanum-aluminum precursor at 700 °C. • Residual OH groups and anions stabilize the nanocomposite structure of perovskite. • Perovskite with a La rich surface with distortions partly persistent upto 1300 °C.
[en] Highlights: ► The stability of orthovanadates (La, Ce, Pr, Nd) VO3 increases down the series. ► Specific heat is calculated for the first time following the structural phase transitions. ► Being less parametric in nature MRIM has successfully predicted the cohesive properties. - Abstract: We have investigated the bulk modulus and thermal properties of orthovanadates RVO3 (R = La, Ce, Pr, Nd) probably for the first time in both monoclinic and orthorhombic phase by incorporating the effect of lattice distortions using the Modified Rigid ion model (MRIM). The calculated bulk modulus, specific heat and other thermal properties reproduce well with the available experimental data, implying that MRIM represents properly the nature of the perovskite type vanadates. The specific heat results can further be improved by including the spin and orbital ordering contributions to the specific heat.
[en] In this paper, we introduce a small molecule-acetylacetone into perovskite precursor to adjust the crystallinity of the perovskite film. Through experiments, we found that acetylacetone not only effectively increase the coverage of perovskite films, but also significantly increase the crystallinity of perovskite crystals and reduce the residual of the solvent in the process of preparing perovskite crystals. As a result, the performance of device treated by the 28 ul · ml−1 acetylacetone achieved a summit PCE of 15.29%, which demonstrated a 17.43% increase compared with the PCE of 13.02% of the original device. (paper)