This article is cited in 3 papers

Phase transitions

Ferroelectricity and pressure-induced phase transitions in HgTiO$_3$

A. I. Lebedev

Lomonosov Moscow State University

Abstract: Using ab initio density functional theory, the ground state of mercury titanate is determined and phase transitions occurring in it at pressures $P\le$ 210 kbar are analyzed. It is shown that the $R3c$ structure experimentally observed in HgTiO$_3$ is metastable at $P$ = 0. The ground state structure at $T$ = 0 varies according to the scheme $R3c\to R\bar3c\to Pbnm$ with increasing pressure in agreement with available experimental data. It is shown that the appearance of ferroelectricity in HgTiO$_3$ at $P$ = 0 is associated with an unstable soft mode. Some properties of crystals in the $R\bar3c$ phase are calculated, in particular, the band gap in the $GW$ approximation ($E_g$ = 2.43 eV), which is in better agreement with experimental data than the value obtained in the LDA approximation (1.49 eV). An analysis of the thermodynamic stability explains why the synthesis of mercury titanate is possible only at high pressures.

Received: 21.12.2011

 English version: Physics of the Solid State, 2012, 54:8, 1663–1668

Bibliographic databases:

•