Pioneering computational insights into the structural, magnetic, and thermoelectric properties of A 3 XN (A=Co, Fe; X=Cu, Zn) anti-perovskites for advanced material applications

This study pioneers the utilization of computer-controlled simulations to elucidate the structural, elastic, electronic, and thermoelectric properties of A 3 XN anti-perovskites (A = Co, Fe; X = Cu, Zn). Starting with the development of a detailed structural model, structural optimization calculations identify the stable Pm-3m cubic phase, aligning with experimental findings. Also, these optimizations indicate the ferromagnetic phase stability of A 3 XN anti-perovskites, further supported by positive Curie-Weiss constants of 60 K, 80 K, and 100 K for Co₃CuN, Co₃ZnN, and Fe₃CuN, respectively. The spin-dependent electronic properties, including band structure and density of states, are explored using multiple exchange-correlation ( XC ) functionals—GGA, GGA + U, and GGA + mBJ. The results uphold the metallic nature of the materials, accompanied by significant spin magnetic moments. Specifically, the calculated values of magnetic moments for Co 3 CuN, Co 3 ZnN, and Fe 3 CuN are 5.08 μ B, 3.70 μ B, and 7.61 μ B, respectively. Furthermore, we compute the Curie temperatures for each compound, 942.48 K for Co 3 CuN, 692.7 K for Co 3 ZnN, and 1400.41 K for Fe 3 CuN, which are substantially elevated, indicating robust ferromagnetic behavior that persists well above ambient conditions. Mechanical properties, including stability, deformation behavior, and ductility, are validated through elastic calculations, with various mechanical anisotropy factors examined. From an application perspective, the thermoelectric characteristics of Co 3 CuN, Co 3 ZnN, and Fe 3 CuN are meticulously evaluated, focusing on parameters like the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor and figure of merit (zT). The analysis highlights promising power factor values of 3.0×10 11 (W/cm.K2), 4.0×10 11 (W/cm.K2), and 6.0×10 11 (W/cm.K2) for Co 3 CuN, Co 3 ZnN, and Fe 3 CuN, respectively, suggesting potential for enhanced efficiency in thermopower generation, particularly in waste heat recovery applications. Furthermore, the study provides a comprehensive analysis of the ground-state optical properties of A 3 XN, including the dielectric constant, photoconductivity, reflectivity, refractive index, absorption coefficient, and extinction coefficient. The reflectivity spectra demonstrate high reflectivity of 45 % across visible and ultravioletregions, suggesting suitability for applications in coatings designed to mitigate solar heating effects.