Structural, Magnetic, and Optical Performance of Al and Mo Doped GaFeO₃

Abstract

Al-and Mo-doped GaFeO₃ (Ga_1−x Al _x FeO₃, GaFe_1−x Mo _x O₃) multiferroic systems were fabricated by double-sintering ceramic method. Single phase of orthorhombic structure with space group Pc2₁n has been obtained. The structure parameters, bond length, and preferential cation distribution were derived from analyzing XRD applying Rietveld method. Rietveld refinement reveals the decrease and increase of the lattice parameters upon Al and Mo doping, respectively. The magnetic properties were studied thoroughly both doped systems. Curie temperatures (T _C) change with increasing Al content amount and reach their maximum value for Al-substituted amounts 15 and 25 % (228 K). On other hand, as the amount of Mo increases, T _c for GaFeO₃, (GFO) decreases. Photoluminescence (PL) spectroscopic measurements were carried out at room temperature, under 330 nm excitation, to sense the reflection of Al and Mo substitutions on the investigated GFO lattice. The presence of the site disorder and cation redistribution was confirmed by PL emission spectral analysis. Fe ³⁺ ions at the tetrahedral and octahedral sites show entirely different luminescence. It was also inferred from the spectra that, at lower Mo content (x), the dominated higher intense PL emissions come from tetrahedrally coordinated Ga³⁺ ions, while in Al-doped GFO at higher Al content (x), the emissions come mainly from the octahedrally sited ions. The luminescent emissions will open up the opportunity of GFO-doped transition metals for both further fundamental studies and technological applications.