Re-examination of the structure of Ba2MIrO6 (MÂ =Â La, Y): space group revised

The structure of the double perovskites Ba2MIrO6 (M = La, Y) has been investigated by the profile analysis of X-ray diffraction data. Both compounds consist of an ordered arrangement of LaO6/YO6 and IrO6 octahedra but with different symmetries. Ba2LaIrO6 is rhombohedral, with the space group R3¯ and the lattice parameters a = 6.04542(5) Å and α = 60.264(1)°, in which the LaO6 and IrO6 octahedra are tilted around the primitive [1 1 1]p-axis of the cubic aristotype. On the other hand, Ba2YIrO6 is found to be double cubic, the space group Fm3¯m, with the lattice parameter a = 8.35032(9) Å.