  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 Fm3m 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 Pm3m 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 Pm3m 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.
