Synthesis and crystal structure of (Ca, R)(Mn, Ti)O 3 (R, rare earth)

Abstract

New compounds of rare earth complex oxides with perovskite structure in a combination of Mn with Ti ions in B-site, Ca 0.5R 0.5Mn 0.5Ti 0.5O 3 (R = La, Nd, Eu) and Ca 0.67R 0.33Mn 0.33Ti 0.67O 3 (R = Y, Gd, Dy, Ho, Yb) were synthesized. The powder X-ray diffraction peaks could be indexed as an orthorhombic cell. Rietveld refinement of X-ray diffraction data were carried out based on the space group Pnma (No. 62) corresponding to GdFeO 3 type perovskite structure. The cell parameters b, c and cell volume increase with increasing ionic radius of rare earth element. The decrease in ionic radius of rare earth ions in these compounds makes increase distortion from ideal cubic perovskite. Although tendencies of bond distances and bond angles by ionic radius of rare earth element are same in these two kinds of compounds, the change in Ca 0.5R 0.5Mn 0.5Ti 0.5O 3 is larger than in Ca 0.67R 0.33Mn 0.33Ti 0.67O 3.