FIRST-PRINCIPLES CALCULATIONS OF STRUCTURE, STABILITY AND THERMODYNAMIC PROPERTIES OF fcc-6LiT UNDER HIGH TEMPERATURES AND PRESSURES

We perform first-principles calculations for fcc-(LiT)-Li-6 in order to study its structure, stability and thermodynamic properties under high temperatures and pressures. We find that melting point of (LiT)-Li-6 (0 GPa) is about 680 K, and rise with the pressures. Reverse equivalent pressure P-r and critical pressure P-c of different temperatures are predicted from partial derivative Delta V/partial derivative P or partial derivative theta/partial derivative P, and they are found to increase with temperature. (LiT)-Li-6 should be stable under the condition of P < 80 GPa and T < 680 K. We also find that pressure and temperature will cause different effect of shear on the {100} and {110} planes. Heat capacity of different pressures increase with temperature and closes to the Dulong-Petit limit at higher temperatures. Debye temperature decreases with temperature, and increases with pressure.