Pressure-dependent phase transition in the ordered BaBi_0.7Nb_0.3O₃ perovskite

Abstract

BaBi_0.7Nb_0.3O₃, an ordered perovskite, crystallizes in a centrosymmetric rhombohedral structure with the space group R3¯. The refined cell parameters obtained from synchrotron powder X-ray diffraction data for the rhombohedral phase at ambient pressure are a=6.109 (2) Å and α=60.3 (1)°. The pressure-dependent synchrotron powder X-ray diffraction studies show a phase transition around 8.44±1 GPa, where it transforms from rhombohedral structure to a monoclinic structure. The lattice parameters obtained for the monoclinic phase at a pressure of 15±1 GPa are a=5.91 (2) Å, b=6.25 (3) Å and c=8.22 (1) Å with monoclinic angle, β=88 (1)°.

Keywords:

• phase transition
• synchrotron X-ray diffraction
• ordered perovskite

PACS :

• 74.62.Fj
• 77.80.Bh
• 61.50.Ks

Acknowledgements

The authors would like to thank the staff of CHESS for their assistance in performing this experiment.