The lattice dynamical and thermo-elastic properties of Rh3X (X = Ti, V) compounds

Due to the attractive high-temperature physical properties, platinum metal-base alloys such as Rh-base alloys make them important materials for various technological applications. To understand deeply the structural, thermo-elastic, and lattice dynamical properties of the L12-type (space number 221) of intermetallic compounds Rh3Ti and Rh3V, we have performed ab-initio density-functional theory within the local density approximation (LDA). Specifically, the phonon dispersion curves and corresponding one-phonon density of states (DOS) for both compounds are computed. Some basic physical parameters such as lattice constant, bulk modulus, elastic constants, shear modulus, Youngʹs modulus, and Poisonʹs ratio are also calculated. Our structural results are consistent with the available experimental and other theoretical data. We have also predicted the temperature and pressure variation of the volume, bulk modulus, thermal expansion coefficient, heat capacity, and Debye temperature in a wide pressure (0–80 GPa) and temperature (0–2000 K) ranges.