First-principles study of Pb2MgTeO6: High-T cubic phase and average low-T rhombohedral phase

Razvan Caracas, Xavier Gonze

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The Pb2MgTeO6 double perovskite is cubic at high temperature and becomes incommensurately modulated with a rhombohedral R3̄ average structure at lower temperatures. Both the cubic and rhombohedral average structures are investigated using the local-density approximation within the density-functional theory: We determine the electronic, structural, dielectric, and zone-center dynamical properties. The computed structural parameters are in reasonable agreement with the experiment, with differences up to 2% for the lattice constants. There are two unstable zone-center vibration modes in the cubic phase. The first unstable mode T1g, 91.19i cm-1, has an antiferrodistortive character, while the second, T1u, 13.92i cm-1, has a ferrodistortive character. There is no unstable zone-center mode in the rhombohedral phase. We establish the correspondence between the zone-center modes in the two phases.

Original languageEnglish
Article number184103
Pages (from-to)1841031-1841037
Number of pages7
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number18
Publication statusPublished - 1 May 2002
Externally publishedYes

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