The effect of disorder in Ba2YTaO6 on the tetragonal to cubic phase transition

Synchrotron X-ray diffraction and Raman spectroscopy have been used to study the structure of the complex perovskite Ba2YTaO6, at temperatures down to 100 K. Where the Ta and Y cations exhibit long-range rock-salt like ordering, Ba2YTaO6 displays a continuous phase transition from a high temperature cubic structure, described in space group Fm3̄m, to a tetragonal, I4/m, structure near 260 K. This transition is inhibited if extensive disorder and/or vacancies are/is present in the sample.

Graphical abstractThe tetragonal–cubic phase transition observed in the cation ordered double perovskite Ba2YTaO6 is inhibited when these are disordered.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Double perovskite Ba2YTaO6 characterised by XRD and Raman spectroscopy. ► Cubic–tetragonal transition in Ba2YTaO6 studied. ► Impact of disorder on the structure and phase transitions established.