Quenching effect of In co-doping on the photoluminescence of ZnGa_2−xIn_xO₄: Cr³⁺ phosphors

ZnGa 2−x In x O 4 : Cr 3+ (1.0 mol%) (x = 0, 0.02, 0.04, 0.06, 0.08, 1.0 and 2.0) nano-powders were synthesized by using the sol gel method. The x-ray diffraction (XRD) results confirmed that the prepared ZnGa 2−x In x O 4 : Cr 3+ samples were cubic in structure. The calculated average crystallite size has values of, 14.6, 16.13, 16.36, 16.49, 16.91, 18.65 and 25.98 nm for an indium molar concentration of x = 0, 0.02, 0.04, 0.06, 0.08, 1.0 and 2.0, respectively. Scanning electron microscope (SEM) images show the formation of cubic structure having a mixture of small and large particles at indium molar concentration of x = 1.0. UV–visible spectrophotometer (UV-vis) measurement show decrease in energy band gap from 4.62 eV to 3.79 eV with increase indium molar concentration from x = 0 to x = 2.0. Photoluminescence (PL) measurement shows that of PL intensity decrease with increasing in the indium molar concentration. The energy dispersive x-ray spectroscopy (EDS) measurement confirm the presence of the Zn, Ga, In, O and Cr ions. The results of this study showed that upon 256 and 267 nm excitations, the emission from the dopant and the host are dominant respectively. The results of this study showed that under excitation of 256 nm with indium molar concentration in range of (x = 0 to x = 0.08) the values of parameters obtained; luminescence emission at 695 nm in the red region and crystallite size in nano range encourage the use of this material for bio imaging applications.