Crystal structure of Ba2InTaO6 as determined by the Rietveld refinement

Rietveld profile analysis of X-ray diffraction data was carried out to determine the symmetry and crystal structures of the double perovskite Ba2InTaO6. Contrary to a recent study of Raman spectroscopy, we find no evidence that Ba2InTaO6 adopts the tetragonal space group P4/mnc of the tilt system a0a0c+. Instead, it has cubic symmetry with the space group Fm3¯m in the temperature range 82–723 K. In Ba2InTaO6 the ordering between In(III) and Ta(V) cations is a difficult process requiring prolonged heat treatment at high temperature.

Enlarged sections of the X-ray diffraction pattern of Ba2InTaO6 showing the basic (222) and (400) reflections. Insert shows the evolution of these reflections as function of temperature. No peak splitting is observed in the temperature range between 82 and 723 K.Figure optionsDownload as PowerPoint slideResearch highlights
► The ordering between In(III) and Ta(V) cations in Ba2InTaO6 is controlled by kinetic process requiring prolonged heat treatment.
► Ba2InTaO6 adopts the cubic space group Fm3¯m instead of tetragonal P4/mnc.
► No phase transition occurs in the temperature range between 82 and 723 K.