Search

This study investigated the structural, elastic, electronic, thermal, magnetic, and optical behavior of GeGa 2 O 4 , FeGa 2 O 4 , GeFe 2 O 4 , and FeFe 2 O 4 spinel oxides based on ab -initio calculations. The results showed that the non-magnetic spinel oxide GeGa 2 O 4 exhibited remarkable physical properties due to Fe occupancy at different lattice sites within the spinel lattice. The Fe containing spinel oxides (FeGa 2 O 4 , GeFe 2 O 4 , and FeFe 2 O 4) were found to be stable in the magnetic phase in contrast to the host GeGa 2 O 4 spinel oxide. The spin polarizations of FeGa 2 O 4 , GeFe 2 O 4 , and FeFe 2 O 4 oxides were calculated as 98.5%, 98.4%, and 100%, respectively. Analysis of the elastic and mechanical properties showed that all of the spinel oxides followed the Born and Huang criteria for mechanical stability. The highest Debye temperature (θ D = 663.77 K) was determined for the FeGa 2 O 4 spinel oxide. For GeGa 2 O 4 , FeGa 2 O 4 , GeFe 2 O 4 , and FeFe 2 O 4 oxides, the calculated structural parameters (cation–anion bond lengths and average values of tetrahedral and octahedral radii) predicted the following cation distributions among the A and B atomic sites: (G e 2 +) [ G a 2 3 + ] O 4 − 2 , (F e 2 +) [ G a 2 3 + ] O 4 − 2 , (G e 4 +) [ F e 2 2 + ] O 4 − 2 , and (F e + 2) [ F e 2 3 + ] O 4 − 2 . The calculated electronic structures indicated that the host GeGa 2 O 4 spinel oxide and FeFe 2 O 4 spinel ferrite were semi-conducting and half-metallic ferromagnetic, respectively, whereas FeGa 2 O 4 and GeFe 2 O 4 oxides exhibited semi-metallic behavior. The GeFe 2 O 4 spinel oxide was found to have the highest saturation magnetization (185.79 emu g−1) and total magnetic moment (8.26 Σ B fu −1). The calculated optical properties indicated the suitability of these oxides for use in optical filters and sensors. The electronic and magnetic characteristics of these spinel oxides with excellent thermal and elastic stability suggest that they have potential uses in diluted magnetic semiconductor devices. [Display omitted] • Effects on physical properties of GeGa 2 O 4 with Fe occupancy are observed. • GeGa 2 O 4 , FeGa 2 O 4 , GeFe 2 O 4, and FeFe 2 O 4 spinels exhibit mechanical anisotropy. • Presence of Fe at A, B, and/or both sites reduces electronic, and optical bandgap. • GeFe 2 O 4 shows semi-metallic behavior with m t o t = 8.26 μ B /f.u and M S = 185.79 emu/g. • The oxides containing Fe have less threshold electronic transition energy. [ABSTRACT FROM AUTHOR]