High Pressure Structural Evolution of Cubic Solid Solution YbInO3

The structural evolution of cubic (c) solid solution YbInO3 (space group Ia3¯) under pressure has been investigated using synchrotron based angle dispersive x-ray diffraction measurements and density functional theory based first principles calculations. A first order irreversible structural phase transition is observed at ∼15 GPa. The ambient cubic phase coexists with the high pressure phase up to the highest pressure achieved in the experiment, i.e., 42 GPa. Based on experimental and theoretical investigations, the high pressure phase of c-YbInO3 is proposed to be an orthorhombic solid solution structure having the space group Pnma. In the high pressure Pnma phase, the coordination of Yb1/In1 (general site 4c) atoms with respect to O atoms increases from six to eight, while Yb2/In2 (special site 4b) atoms remain in six coordination. Our theoretical calculations show that distorted octahedra (YbO6 and InO6), sitting at the general position in c-YbInO3, change its geometry toward regular octahedra with increasing pressure, which gives rise to the phase transformation.