Crystal structures and phase transitions in Sr2InTaO6 perovskite

Abstract

The preparation and crystal structure of the double perovskite oxide Sr2InTaO6 are reported. This oxide has a monoclinic structure in space group P21/n at room temperature, where In and Ta display a rock-salt type ordering with a = 5.73356(10), b = 5.74052(10), c = 8.10905(14) Å and β = 90.022(6)°. Variable temperature neutron diffraction measurements demonstrate this displays the sequence of phase transitions P21/n⟶605∘CI2/m⟶705∘CI4/m⟶930∘CFm3ˉm as a consequence of the sequential loss of tilting of the corner shared octahedra upon heating. The evolution of Sr2InTaO6 crystal structure upon heating is analysed and described in terms of symmetry-adapted distortion modes. The GM4+ and X3+, that are responsible for anti-phase and in-phase tilting, respectively, are highly temperature dependent, with the GM4+ mode having the largest amplitude at room temperature. © 2013, Springer.