Evolution of Crystallographic Phases in (Sr1−xCax)TiO3 with Composition (x)

Abstract

Results of X-ray powder diffraction, neutron powder diffraction, electron microdiffraction, and convergent beam electron diffraction (CBED) studies are presented to show that the space group of (Sr1−xCax)TiO3 (SCT) in the composition range 0.35<x≤0.55 cannot be Cmcm. The correct space groups are Pbcm for 0.35<x≤0.40 and Pbnm for 0.40<x≤0.55. The analysis of powder XRD data reveals that the structure of SCT is noncubic for x≥0.06. It is shown that four different types of orthorhombic phases appear in the SCT system with increasing Ca2+ content.