Hierarchical zinc aluminate 3D nanostructures, synthesized by bio-inspired ultrasound assisted sonochemical route: Display and dosimetry applications

Abstract

ZnAl2O4:Tb3+ (0.25–5 mol%) nanophosphors were synthesized by ultrasound assisted sonochemical route using bio-sacrificial Aloe Vera (A.V.) gel as a template. The effect of sonication time, A.V. gel concentration, pH value, sonication power and temperature on the morphologies of the prepared samples were systematically explored and discussed. Probable formation mechanism for various morphologies of ZnAl2O4:Tb3+ nanophosphors was discussed. Structural and luminescence properties of the obtained samples were thoroughly investigated. Rietveld refinement of the prepared samples exhibit cubic structure with Fd3¯m space group. Thermoluminescence (TL) glow curves exhibit a well resolved glow peak at ∼197 °C. TL intensity was found to increase linearly up to 1 kGy and thereafter it shows sub-linear behavior with increase of dose which indicates that the present phosphor was quite useful for TL dosimetry. Kinetic parameters related with the glow peaks were estimated by different methods. Photoluminescence spectra shows the characteristic Tb3+ ions peaks at ∼488 nm, 542 nm, 584 nm and 622 nm corresponding to 5D4 → 7FJ (J = 3, 4, 5 and 6) transitions respectively. The chromaticity co-ordinates of all the phosphors were well located in green region. Therefore, the present phosphor was quite useful as green component of white light-emitting diodes. Keywords: Bio-inspired synthesis, Nanostructures, Photoluminescence, Thermoluminescence, Judd-Ofelt analysis