Eur. Phys. J. Appl. Phys. 53, 11101 (2011)
https://doi.org/10.1051/epjap/2010100192

Ab initio calculations of elastic and thermodynamic properties of fcc-⁶LiF under high temperatures and pressures

¹ School of Science, Chongqing Jiaotong University, Chongqing, 400074, P.R. China
² Department of physics, Henan Institute of Education, Zhengzhou, 450046, P.R. China
³ Institute of Nuclear Physics and Chemistry, CAEP, Mianyang, 621900, P.R. China
⁴ Institute of Theoretical Physics, China West Normal University, Nanchong, 637002, P.R. China
⁵ Institute of Atomic and Molecular of Sichuan University, Chengdu, 610065, P.R. China

Corresponding author: wfbgc@yahoo.com.cn

Received: 10 May 2010
Revised: 7 September 2010
Accepted: 11 October 2010
Published online: 23 December 2010

Abstract

The elastic and thermodynamic properties of fcc-⁶LiF under high temperatures and pressures are investigated using the ab initio method and quasi-harmonic Debye model. The lattice constant of ⁶LiF at ground state is a little larger than that of LiF. When pressure is less than 10 GPa, crystal lattice is compressed easily at low temperature, and when P > 10 GPa, lattice can be compressed easily at high temperature. C₁₁ increases with pressure and reduces with temperature sensitively. C₁₂ and C₄₄ raise or decrease just a little with increasing pressure and temperature. Heat capacity of different pressure increases with temperature and closes to the Dulong-Petit limit at higher temperatures. Debye temperature decreases with temperature, and increases with pressure. Furthermore, under lower pressure, thermal expansion coefficient raise rapidly with temperature, and the increasing trend will get slow at higher pressure.