Pressure dependence of thermal physical properties of A-type R2O3 (R=Y, La): A first-principles study

The mechanical, electronic and thermal physical properties of A-type R2O3 (R=Y, La) under hydrostatic pressure are studied by first-principles calculations. The calculated band gap is 6.3eV (5.9eV) for Y2O3 (La2O3). Under hydrostatic pressure, both phases show anisotropic elasticity in different crystallographic directions. The isothermal bulk modulus of R2O3 decreases monotonically with the increasing of temperature from 300K to 1500K. The intrinsic ductile nature of both phases is confirmed by the obtained B/G ratio. The temperature dependence of linear TECs of La2O3 is stronger than that of Y2O3, and the linear TECs in [001] direction show larger values in both phases than those in [010] direction. At room temperature, the average linear TECs for Y2O3 and La2O3 are 8.40×10−6K−1 and 8.42×10−6K−1, respectively. Other thermal physical properties such as specific heats (CV, and CP), entropy (S), sound velocity and Debye temperature are also obtained.