First-principles study of Pb2MgTeO6: High-T cubic phase and average low-T rhombohedral phase
(2002) Physical review. B, Condensed matter and materials physics — Vol. 65, n° 18, p. 184103:1-184103:7 (2002)
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- Abstract
- The Pb2MgTeO6 double perovskite is cubic at high temperature and becomes incommensurately modulated with a rhombohedral R (3) over bar 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 T-1g, 91.19i cm(-1), has an antiferrodistortive character, while the second, T-1u, 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.
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Citations
Caracas, R., & Gonze, X. (2002). First-principles study of Pb2MgTeO6: High-T cubic phase and average low-T rhombohedral phase. Physical review. B, Condensed matter and materials physics, 65(18), 184103:1-184103:7. https://doi.org/10.1103/PhysRevB.65.184103 (Original work published 2002)