Anisotropic assessment of ultrasonic wave velocity and thermal conductivity in ErX (X:N, As)

Abstract

The elastic and ultrasonic properties of erbium nitride (ErN) and erbium arsenide (ErAs) have been investigated in the temperature range 0-300K. The second order elastic constants (SOECs) have been obtained using Coulomb and Born-Mayer potentials up to second nearest neighbours. SOECs have been used to evaluate various mechanical and thermal parameters which provide knowledge about the future performance of ErX. Mechanical properties such as Young's modulus, bulk modulus, shear modulus, Zener anisotropy factor, Poisson's ratio and toughness to fracture ratio (G/B) have also been calculated. The chosen materials are found to be brittle and anisotropic in nature. The ultrasonic wave velocities for longitudinal and shear modes of propagation along <100>, <110> and <111> crystallographic directions have also been computed at room temperature using evaluated values of SOECs and density of the chosen materials. These properties have been visualized using MTEX 4.0.22 software for ErAs. The ultrasonic wave velocity computed along different orientations is an important physical quantity in studying the thermal properties such as Debye temperature and anisotropic thermal conductivity. These properties play a significant role in quality control in material producing industries. The obtained results are discussed in correlation with mechanical and thermophysical properties of the materials.