Structural relationship between negative thermal expansion and quartic anharmonicity of cubic ScF3 |
| |
Authors: | Li Chen W Tang Xiaoli Muñoz J A Keith J B Tracy S J Abernathy D L Fultz B |
| |
Affiliation: | Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, California 91125, USA. chenwli@gmail.com |
| |
Abstract: | Cubic scandium trifluoride (ScF3) has a large negative thermal expansion over a wide range of temperatures. Inelastic neutron scattering experiments were performed to study the temperature dependence of the lattice dynamics of ScF3 from 7 to 750 K. The measured phonon densities of states show a large anharmonic contribution with a thermal stiffening of modes around 25 meV. Phonon calculations with first-principles methods identified the individual modes in the densities of states, and frozen phonon calculations showed that some of the modes with motions of F atoms transverse to their bond direction behave as quantum quartic oscillators. The quartic potential originates from harmonic interatomic forces in the DO9 structure of ScF3, and accounts for phonon stiffening with the temperature and a significant part of the negative thermal expansion. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|