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

Published

February 1, 2001

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 (δE_VASP) for a large number of ordered supercells in the perovskite based system NaTiO₃ - BiTiO₃, including 36 supercells with the [Na_1/2Bi_1/2] TiO₃ (NBT) composition. The δE_VASP were used to fit a cluster expansion Hamiltonian to verify that the no other superstructure is predicted to have lower energy than the lowest δE_v ^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

Pub Type

Conferences

Keywords

cation ordering, ground states, relaxor ferroelectrics

Citation

Burton, B. and Cockayne, E. (2001), Prediction of the [Na_1/2Bi_1/2] TiO₃ Ground State, Workshop on Fundamental Physics of Ferroelectrics | 11th | Fundamental Physics of Ferroelectrics 2001: 11th Williamsburg Workshop | AIP (Accessed May 18, 2024)