Solvothermal synthesis and luminescent properties of hierarchical flowerlike ZnAl2O4:Ho3+ microstructures

Abstract Hierarchical microstructures of ZnAl 2 O 4 :Ho 3+ (0.25–5 mol %) nanophosphors (NPs) were synthesized via solvothermal route using Epigallocatechin gallate (EGCG) as a bio-surfactant. The effect of EGCG concentration on the morphology was studied in detail. The Powder X-ray diffraction (PXRD) studies confirm the cubic phase of the samples. The photoluminescence (PL) emission spectra exhibit peaks at ∼ 540, 553 and 666 nm were due to transitions 5 F 4 → 5 I 8 , 5 S 2 → 5 I 8 and 5 F 5 → 5 I 8 of Ho 3+ ions, respectively. Thermoluminescence (TL) properties of ZnAl 2 O 4 : Ho 3+ (0.25–5 mol %) NPs were studied after exposure of 60 Co γ-rays at a warming rate of 6 °Cs −1 . The TL intensity was found to increase with γ-dose. The kinetic parameters have been determined using Chen's method from the deconvoluted glow curve. The CIE Chromaticity co-ordinates of all the prepared phosphors were located in the blue region. The above results clearly evident that the optimized Ho 3+ activated ZnAl 2 O 4 NPs was a promising single phased phosphor for WLED's and dosimetry applications.