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

Published

Author(s)

Eric J. Cockayne

Abstract

We compare first-principles (FP) calculations of the ionic effective charges, phonon frequencies, and static dielectric permittivities ks of several perovskite-type materials. Transition metal ions have anomalously large effective charges, though in the double perovskite CaAll/2Nbl/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 (CaAll/2Nbl/203)1-x(CaTiO3)x (CAN-CT), ks is modeled via a cluster expansion, with the parameters determined from FP. In pure CAN, ks 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

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 April 21, 2024)
Created November 1, 2003, Updated February 19, 2017