Elastic and Ultrasonic Properties of Rare-earth Lutetium Monopnictides

Abstract

We present ultrasonic properties of lutetium monopnictides (LuPn: Pn = As and Sb) with the help of second and third order elastic constants in the temperature range 100–300 K. These elastic constants have been computed using Coulomb and Born–Mayer potential with the help of two basic parameters i.e., nearest neighbor distance and hardness parameter. First these elastic constants are applied to compute some mechanical constants such as bulk moduli (B), shear moduli (G), tetragonal moduli (Cs), Poisson’s ratio (ν) and Zener anisotropy ratio (A). The fracture to toughness ratio i.e., G/B was found greater than 0.57, therefore LuAs and LuSb are brittle in nature. In second part of present investigation we evaluated ultrasonic properties such as wave velocities for longitudinal and shear modes, Debye average velocity, Debye temperature and Gruneisen parameters, thermal relaxation time, thermal conductivity, acoustic coupling constants and ultrasonic attenuation due to phonon–phonon interaction along 〈100〉, 〈110〉 and 〈111〉 orientations. The achieved results of present work are compared and discussed with other rare-earth monopnictides.