Thermal properties of Fe₂₃Zr₆ intermetallic compound under pressure and temperature: A DFT study

Fe₂₃Zr₆ intermetallic phase is formed in SS-15Zr alloy which is a promising material for high level metallic waste immobilization. We have studied thethermodynamic properties, viz., specific heat at constant volume (C_V), entropy (S) and vibrational Helmholtz free energy (F_vib) of Fe₂₃Zr₆ phase as a function of pressure and temperature using density functional theory. The phase is found to be dynamically stable and increase of temperature or decrease of pressure makes the phase more stable. Constant volume specific heat (C_V) of the phase at high temperatures (T > 500 K) does not change with temperature.