First-principles calculations to investigate the structural, electronic, magnetic and thermoelectric properties of ARh2O4 (A = Co, Ni, Cu, Zn) oxides

Structural, elastic, magnetic, electronic and thermoelectric properties of ARh2O4 (A = Co, Ni, Cu, Zn) oxides are calculated theoretically. Density functional calculations are performed by employing Wien2k simulation code. Calculations reveal that the ARh2O4 oxides are structurally and mechanically stable. For all spinel oxides, calculation reveals high anisotropic behavior of mechanical properties. Elastic properties show ductile and covalent bonding nature, whereas thermal properties reveal that the oxides have high melting and Debye temperature. Electronic properties (band structure and DOS) reveal that the CoRh2O4 and ZnRh2O4 oxides exhibit ptype semi-conductive behavior for both spin states. The NiRh2O4 oxide shows half-metallic behavior while semimetal and metallic nature of CuRh2O4 oxide is observed for up(up arrow) spin and down(down arrow) spin states, respectively. Spinpolarized electronic structures of CoRh2O4 and NiRh2O4 oxides are found to exhibit 100% spin-polarization while CuRh2O4 and ZnRh2O4 oxides show 69% and 0.23% spin-polarization, respectively. Calculated total magnetic moment (mtot) per molecule and saturation magnetization (MS) show that the CoRh2O4, NiRh2O4, and CuRh2O4 oxides have magnetic exchange interactions between their tetrahedral and octahedral sites whereas no magnetic interaction is found between A and B sublattices of ZnRh2O4 oxide. Calculated thermoelectric properties show that these oxides are good materials for thermoelectric applications. Among these four oxides, the ZnRh2O4 exhibits figure-of-merit (ZT = 3.92 at 700 K) and Seebeck coefficient, S = 236.3 x 10-6 V/K at room temperature which suggests a better candidate for thermoelectric devices.

Automated summary

Theoretical calculations were performed on the structural, elastic, magnetic, electronic, and thermoelectric properties of ARh2O4 (A = Co, Ni, Cu, Zn) oxides. The results show that these oxides are structurally and mechanically stable. They exhibit high anisotropic behavior in their mechanical properties and have ductile and covalent bonding nature in their elastic properties. The electronic properties reveal different conductive behaviors for each oxide, with some showing metallic, semimetallic, or p-type semiconductive behavior. Additionally, the oxides have magnetic exchange interactions and exhibit good thermoelectric properties, with ZnRh2O4 being the most promising candidate for thermoelectric devices.