Crystal structure of Ca(Fe0.4Si0.6)O2.8 oxygen-deficient perovskite

The crystal structure of Ca(Fe3+0.4Si0.6)O2.8 oxygen-deficient perovskite phase synthesized at 12 GPa and 1400 °C was studied using synchrotron powder X-ray diffraction. The phase is isostructural to low-pressure phase of Ca(Al0.4Si0.6)O2.8. The structure was refined by the Rietveld method and is consists of a perovskite-like triple-layer of corner-shared (Fe3+,Si)O6 octahedra and a double-layer of SiO4 tetrahedra those are stacked alternatively in the [111] direction of ideal cubic perovskite. Small degree of Fe3+/Si disorder was detected between two octahedral sites. The structure is compared with other oxygen-deficient perovskites.