Thermodynamic Properties of Fe2B Under High Pressure from First-principles Calculations

Equation of state (EOS) and other thermodynamic properties of Fe2B are studied using first- principles calculations based on the plane wave full potential density functional theory method within the generalized gradient approximation (GGA) for exchange and correlation. It is demonstrated that the ratio c/a of about 1.271 is the most stable structure for the Fe2B, which is consistent with the experimental data. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the dependences of the relative volume V/V0 on pressure P, cell volume V, and on temperature T, are successfully obtained. The variations of the Debye temperature θ(V), the thermal expansion α, and the heat capacity CV as a function of pressure P and temperature T, are investigated systematically in the ranges of 0-50 GPa and 0-1000 K.