Charge ordering induced metal–semiconductor transition in Ag 2BiO 3: A first-principles study

Abstract

Accurate ab initio density-functional calculations are performed to investigate the relationship of the ground-state crystal structures and electronic properties of Ag 2BiO 3 compound. The results indicate that Ag 2BiO 3 in Pnna phase, in which the bismuth atoms occupy the same Wyckoff positions, exhibits metallic conductivity, while in Pnn2 and Pn phases, Ag 2BiO 3 exhibits semiconducting character, which is in agreement with the experimental results. Charge ordering is indeed induced by the crystal inversion twin in the Pnn2 phase compared with the Pnna phase. In the low temperature phase Pn, the charge ordering is similar to that of Pnn2 phase although it is more distorted in Pn phase. In addition, the calculation indicates that the charge ordering is caused in the 6s electron rearrangement.