First-Principles Calculations of the Dielectric Properties of Perovskite-Type Materials

Published

November 1, 2003

Author(s)

Eric J. Cockayne

Abstract

We compare first-principles (FP) calculations of the ionic effective charges, phonon frequencies, and static dielectric permittivities k_s of several perovskite-type materials. Transition metal ions have anomalously large effective charges, though in the double perovskite CaAl_l/2Nb_l/20₃ (CAN), the effective charge of Nb is significantly lower than in the simple pervoskite KnbO₃, showing different Nb-0 bonding chemistry. Tolerance factors, cation chemistry, and structure phase transitions all affect the nature of the softest phonons in perovskites. For the solid solution (CaAl_l/2Nb_l/20₃)_1-x(CaTiO₃)x (CAN-CT), k_s is modeled via a cluster expansion, with the parameters determined from FP. In pure CAN, k_s is found to increase when cation order increases, in agreement with experimental results on analogous systems. The dielectric constant of CAN-CT increases nonlinearly with x, in agreement with experiment.

Proceedings Title

Proceedings Issue of the MMA 2002 Meeting

Volume

23

Issue

No. 14

Conference Dates

August 31-September 4, 2002

Conference Location

York, UK

Conference Title

Journal of the European Ceramic Society

Pub Type

Conferences

Keywords

dielectric properties, first-principles calculations, perovskites

Citation

Cockayne, E. (2003), First-Principles Calculations of the Dielectric Properties of Perovskite-Type Materials, Proceedings Issue of the MMA 2002 Meeting, York, UK (Accessed December 26, 2024)