Exploring the Essential Physical Characteristics of Tetragonal M2O3 (M = Zr, Hf) via First-Principles for Extreme Environment Suitability

Abstract

To identify resilient materials for nuclear reactors, DFT calculations were systematically performed to observe the structural, phonon, mechanical, anisotropic elastic, electronic, thermophysical, and optical properties of tetragonal M₂O₃ (M = Zr, Hf). The structural parameters and c/a ratio show good agreement with existing data. The band structure and DOS calculations display that both the compounds are semi-metallic and non-magnetic. The formation energy, phonon dispersion, and elastic constants calculations confirm the structural, dynamical, and mechanical stability. The investigated materials possess ductility, as verified by Pugh’s ratio (B/G) and Poisson’s ratio (σ). Various key thermophysical properties, such heat capacity, thermal expansion, Debye temperature, melting point, and thermal conductivity, have been studied for the first time. Both compounds exhibit high lattice thermal conductivity values of 42.77 and 22.15 Wm^-1K^-1 at 300 K, with melting points recorded at 2147.79 K and 2201.76 K, for Zr₂O₃ and Hf₂O₃, respectively; which predict their potentiality for applications in high-temperature environments. Additionally, the investigation of optical properties suggests that tetragonal M₂O₃ (M = Zr, Hf) compounds hold significant potential for use in optoelectronic devices, especially in the UV spectral range. This study provides a solid computational foundation for experimental verification, highlighting their potential for enhanced performance.