Visualizing electronic structure changes across an antiferroelectric phase transition: Pb2MgWO6

Abstract

Pb ₂ MgWO ₆ is an ordered perovskite or elpasolite that undergoes a phase transition from a cubic paraelectric phase to an orthorhombic antiferroelectric phase below 310 K. Through an analysis of the electronic structures of both the high and low temperature phases using high level band structure methods, the nature of the changes in the bonding across the phase transition has been examined. The key stereochemical rôle of the lone pairs on the lead atoms has been examined by use of the Electron Localization Function. While the lone pairs on the lead atoms are smeared out by the near octahedral symmetry of the lead sites in the high temperature phase, at low temperatures they localize into the traditional lobes. These changes have been visualized.