Structural, magnetic, optical, and photoresponse studies of hydrothermally prepared nanocrystalline GaxFe2-xO3 (x=0.7, 1 & 1.3)

Abstract

Effect of gallium content on the structural, magnetic, optical and optoelectronic properties of nanocrystalline gallium ferrite GaxFe2-xO3 (x = 0.7, 1 & 1.3) prepared via hydrothermal synthesis is reported herein. X-ray diffraction, FTIR, Raman spectroscopy, and scanning electron microscopy techniques are used to study the structural and morphological properties of the samples. The crystal structure for all of the samples is single-phase orthorhombic with a P212121 space group. The structural investigation via Rietveld refinement of XRD shows a decrease in lattice parameters and volume with increasing gallium content. The structural modifications with Ga content are also confirmed from the Raman analysis and FTIR analysis. The scanning electron microscopy indicates that the size of nanoparticles is < 150 nm for all the samples, and particle size increases with Ga content. The optical and magnetic properties of GaxFe2-xO3 is not varying monotonically with x and are distinctly different from most studied Pc21n structures of GFO samples, which indicate the influence of pressure-induced cation site disorder during hydrothermal synthesis. The composition with x = 1 shows relatively less cation disorder. UV absorption analysis proves that the band gap decreases with increasing Ga concentration. The photoluminescence lifetime and quantum yield results also demonstrate the significant variation with Ga concentrations. A relatively high fluorescence value is observed for GFO with x = 1. The thin films with x < 1 show a negative photoconductive gain, whereas those with x > 1 show a positive gain. This study suggests that hydrothermally prepared nanocrystalline gallium ferrite's structural, magnetic, optical, and photosensitivity properties can be largely tailored with Ga content. The cation site disorder also plays a significant role in modulating the magneto-optical properties of this system. The photosensitivity exhibited by the multiferroic GFO systems opens an avenue into optoelectronic applications of this material.