Investigation of crystal structure of SrLa(FeTi)O6 and BaLa(FeTi)O6 perovskites by rietveld refinement

• Investigation of crystal structure of SrLa(FeTi)O6 and BaLa(FeTi)O6 perovskites by Rietveld Refinement at room temperature.
• Structural analysis rules out the cubic structure with space grop Fm  3¯m for BaLa(FeTi)O6 and tetragonal structure with space group Pnma for BaLa(FeTi)O6 as reported by earlier authors.
• We have reported the cubic structure with space group Pm  3¯m for BaLa(FeTi)O6 and orthorhombic structure with space group Pnma for SrLa(FeTi)O6.

The structures of the recently reported ordered perovskites SrLa(FeTi)O6 and BaLa(FeTi)O6 have been revisited using Rietveld analysis of the powder x-ray diffraction data. Our studies clearly show that earlier authors have incorrectly reported the tetragonal structure in the I4/m space group for SrLa(FeTi)O6 and the cubic structure in the Fm  3¯m space group for BaLa(FeTi)O6. The correct structure is found to be orthorhombic in the Pnma space group for SrLa(FeTi)O6 while cubic in the Pm  3¯m space group for BaLa(FeTi)O6. Thus the BaLa(FeTi)O6 is not an ordered double perovskite as the occupancies of Ba/La ions at A-site and Fe/Ti ions at B-site are disordered resulting in the primitive cubic unit cell in the Pm  3¯m space group. Similarly, the occupancies of Sr/La ions at A-site and Fe/Ti ions at B-site are disordered in SrLa(FeTi)O6 also, ruling out the ordered perovskite structure.

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