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Prediction of the [Na1/2Bi1/2] TiO3 Ground State

Published

Author(s)

Benjamin P. Burton, Eric J. Cockayne

Abstract

The Vienna Ab-initio Simulation Package (VASP) was used to perform fully relaced, planeware psudopotential calculations of formation energies (δEVASP) for a large number of ordered supercells in the perovskite based system NaTiO3 - BiTiO3, including 36 supercells with the [Na1/2Bi1/2] TiO3 (NBT) composition. The δEVASP were used to fit a cluster expansion Hamiltonian to verify that the no other superstructure is predicted to have lower energy than the lowest δEv ^ASP^, which is a 40 atom supercell with space group symmetry Pm. Its chemical ordering is characterized by pseudocubic doubling of the cell constants, with alternating [100] rows of Na and Bi atoms in (hk0) planes plus alternating [010] rows in (hk1/2) planes. Chemical ordering alone reduces space group symmetry from cubic, Pm3m, to tetragonal, P42/mmc, and octahedral tilting (a_a_c+ system)further reduces it to monoclinic, Pm.
Proceedings Title
Workshop on Fundamental Physics of Ferroelectrics | 11th | Fundamental Physics of Ferroelectrics 2001: 11th Williamsburg Workshop | AIP
Volume
582
Conference Dates
February 4-7, 2001
Conference Title
AIP Conference Proceedings

Keywords

cation ordering, ground states, relaxor ferroelectrics

Citation

Burton, B. and Cockayne, E. (2001), Prediction of the [Na<sub>1/2</sub>Bi<sub>1/2</sub>] TiO<sub>3</sub> Ground State, Workshop on Fundamental Physics of Ferroelectrics | 11th | Fundamental Physics of Ferroelectrics 2001: 11th Williamsburg Workshop | AIP (Accessed June 16, 2024)

Issues

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Created February 1, 2001, Updated February 17, 2017