Synthesis, characterization and studies of radiative properties on Eu3+-doped ZnAl2O4

Abstract

Eu3+-doped ZnAl2O4 phosphors were successfully synthesized in air atmosphere at 900°C. The phosphors were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermally stimulated luminescence (TSL) and photoluminescence (PL) techniques. The average particle size of the system as determined from SEM was found to be 100–150nm (for samples annealed at 900°C). PL spectra of the doped phosphors showed emission peaks corresponding to Eu3+ ions. Lifetime studies revealed Eu3+ ions to be in two different sites. The asymmetric ratio (I616/I592) was observed to be about 3.75. This suggested that Eu3+ ion entered the host mainly substituting Al3+ site distorting the local environment and is partly located on surface of the phosphors. A prominent glow peak at 430K was observed in the TSL of γ-irradiated Eu3+-doped ZnAl2O4 phosphors. Trap parameters for this peak have been determined and the probable mechanism for the glow peak is proposed. CIE chromaticity coordinates for the system were evaluated. It was observed that, the system could be employed as a potential red emitting phosphor. Commercial utility of the phosphor was investigated by comparing it with commercial red phosphor. The PL intensity of the as prepared phosphors was 63% of that of the commercial phosphor. Apart from this, various radiative properties such as the Judd–Ofelt intensity parameters, spontaneous emission probabilities, luminescence branching ratios, radiative lifetimes and quantum efficiency were evaluated for the system.