Reststrahlen Band Studies of RuCrX (X = Si, Ge, Sn) Half Heusler Alloys

Abstract

Reststrahlen band measurements in RuCrX (X = Si, Ge, Sn) Half Heusler Alloys (HHAs) for Far Infrared (FIR) spectroscopy are pointed out in this article by using Density Functional Theory (DFT). Generalized Gradient Approximation (GGA) as an exchange–correlation functional in the WIEN2k-package is used for structural optimization while Martin Troullier norm-conserving pseudo-potentials in Quantum ESPRESSO (QE) are used for structural optimization and lattice dynamic study of the alloys. Phonon dispersion curves elucidate dynamical stability and reststrahlen bands of the alloys. It is found that all alloys are dynamically stable in C1b structure and reststrahlen bands for RuCrX (X = Si, Ge, Sn) are 2.92 THz (Δλ = 102.62 μm), 0.96 THz (Δλ = 311.18 μm) and 0.81 THz (Δλ = 366.98 μm) respectively. This predicts RuCrSi HHA has a larger reststrahlen band that corresponds to being more polar in nature than other alloys. The calculated reststrahlen values for all alloys are in the FIR spectral region, so they can be used to manufacture the FIR-devices.