The mechanical, vibrational and thermodynamic properties of glass-ceramic lithium thiophosphates Li4P2S6

The mechanical, vibrational and thermodynamic properties of Li4P2S6 are investigated through the firstprinciples calculations. The predicted lattice parameters agree with the available experimental data and theoretical results. The mechanical and vibrational properties are calculated, indicating that Li4P2S6 is mechanical and dynamically stable, have a brittleness character and the Vickers hardness is 5.7 GPa. The anisotropy property is studied by the percent anisotropy, the universal anisotropic indexes and three-dimensional surface contour of elastic modulus. Furthermore, the three-dimensional surface contour of the minimum thermal conductivity is obtained. Using the linear response theory, the phonon and thermodynamic properties are obtained. The dielectric tensors epsilon and the Born effective charges Z* are also investigated. Finally, the symmetry of the normal modes of vibration, the infrared and Raman activity are predicted. (C) 2019 Elsevier B.V. All rights reserved.