Effects of cation vacancy distribution in doped LaMnO3+δ perovskites

Cation sites in Al-rich MgSiO3 perovskites

Local structure analysis of Al-containing magnesium silicate perovskite has been carried out with X-ray absorption spectra recorded at the Mg, Al, and Si K-edges using the SA32 beam-line of SuperAco (Orsay, France). The Al-XAFS spectrum of (MgSi)0.85Al0.3O3 perovskite (synthesized in a multi-anvil apparatus) cannot be explained by assuming that Al31 occurs in octahedral or dodecahedral sites on...

Cation-anion vacancy complexes in semiconducting compounds

Analysis of oxygen vacancy in Co-doped ZnO using the electron density distribution obtained using MEM

Oxygen vacancy (VO) strongly affects the properties of oxides. In this study, we used X-ray diffraction (XRD) to study changes in the VO concentration as a function of the Co-doping level of ZnO. Rietveld refinement yielded a different result from that determined via X-ray photoelectron spectroscopy (XPS), but additional maximum entropy method (MEM) analysis led it to compensate for the differe...

Clustering of divalent cation-vacancy pairs in alkali halide crystals

The analysis of experimental results of the clustering of divalent cation-vacancy pairs by Unger and Perlman is shown here to be unable to distinguish between their model of dimer formation and the earlier model of' Dryden for trimer formation under the conditions where it has been applied. In general, experimental results appear to correspond to overall third order kinetics in the pre-plateau ...

Jahn-Teller distortions, cation ordering and octahedral tilting in perovskites.

In transition metal oxides, preferential occupation of specific d orbitals on the transition metal ion can lead to the development of a long-range ordered pattern of occupied orbitals. This phenomenon, referred to as orbital ordering, is usually observed indirectly from the cooperative Jahn-Teller distortions (CJTDs) that result as a consequence of the orbital ordering. This paper examines the ...