Pressure-induced phase transition and octahedral tilt system change of Ba2BiSbO6

High-resolution X-ray synchrotron powder diffraction studies under high-pressure conditions are reported for the ordered double perovskite Ba2BiSbO6. Near 4 GPa, the oxide undergoes a pressure-induced phase transition. The symmetry of the material changes during the phase transition from space group R3¯ to space group I2/m, which is consistent with a change in the octahedral tilting distortion from an a−a−a− type to a0b−b− type using the Glazer notation. A fit of the volume–pressure data using the Birch–Murnagaham equation of state yielded a bulk modulus of 144(8) GPa for the rhombohedral phase.

Fitting of the diffraction peaks of Ba2BiSbO6 is shown at an applied pressure of 6.1 GPa. The tick marks are the allowed positions of the Bragg reflections in space groups R3¯ (top) and I2/m   (bottom), which illustrates the pressure-induced phase transition from space group R3¯ at ambient pressure to the high-pressure I2/m form.Figure optionsDownload as PowerPoint slide