SKM 2023 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 21: Thermal properties
HL 21.2: Talk
Tuesday, March 28, 2023, 11:15–11:30, POT 251
The Influence of Anharmonicity on Negative Thermal Expansion of α-Sn — •Reinhard K. Kremer1, Paweel T. Jochym2, Jan Lazewski2, Andrzej Ptok2, Przemyslaw Piekarz2, Andrzej M. Olés3, and Eva Brücher1 — 1MPI for Solid State Research, Stuttgart, Germany — 2Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland — 3Institute of Theoretical Physics, Jagiellonian University, Krakow, Poland
The lattice vibrational properties of α-Sn (gray tin) were investigated experimentally by temperature dependent x-ray diffraction and theoretically by density functional theory calculations. Similar to the other elements of group IV, α-Sn exhibits a lattice anomaly at low temperatures and negative thermal expansion, with a minimum at ∼27 K and a magnitude three times larger than in Si. Influence of anharmonic effects up to 4th order potential terms on the phonon dispersion relations, the lattice parameters, and the thermal expansion coefficient have been tested. The performed analysis gives an excellent agreement with experiment when quartic potential terms are included in the theory. We point out that negative thermal expansion in α-Sn is not driven by anharmonicity of interatomic potential. This resolves the long-standing puzzle in the thermal behavior of α-Sn.