First principles insight into physical properties of CaX2O4 (X = In, Gd) spinels for optical and spintronic applications

Herein, the calcium based ternary spinel oxides CaX2O4 (X = In, Gd) are brought under theoretical investigation to study their structural, magnetic, opto-electronic, and thermoelectric features. Thermodynamical and structural stabilities are assured through the assessment of enthalpy of formation (-6.243 and -7.542 eV for CaIn2O4 and CaGd2O4, respectively) and tolerance factor (0.96 and 0.86 for CaIn2O4 and CaGd2O4, respectively). DFT + U based computations of band structures and density of states define CaIn2O4 as nonmagnetic wide bandgap (Eg) semiconductor (direct Eg of 3.88 eV) while CaGd2O4 is found to be half-metallic ferromagnetic spinel (direct Eg of 3.82 eV in spin down channel and & mu;Total = 28 & mu;B). Highly optically conductive and absorptive behavior in UV region has been observed for both oxide spinels, which suggests their prime usability in the field of optoelectronics. Furthermore, thermoelectric (TE) efficiency of both materials is disclosed by determining figure-of-merit (ZT) values which are found to be higher than 0.75 at room temperature. Optoelectronic and TE characteristics of both spinel oxides along with greater stability highly suggest their potential applications in various thermoelectric generators. aeronautics and optical devices operating within ultraviolet region of light.