Rare earth doped hydrated and anhydrous zinc phosphate nanophosphors: A promising white light emitter

Abstract

This study explores the viability of rare earth doped zinc phosphate nanophosphors as probable candidates for white light emission. Novel single, double and triple doped hydrated and anhydrous Zn3(PO4)2:RE (RE=Eu, Tb, Ce) nanophosphors have been synthesized through a simple sonochemical process and characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectrophotometry. The results of XRD and TEM show that resultant nanophosphors are single phase and rod shaped. The doped samples showed multi color emission on single wavelength excitation. The difference in emission characteristics between Zn3(PO4)2(H2O)4:Eu3+(5%) and Zn3(PO4)2:Eu3+(5%) have been discussed. Energy transfer was observed from Tb3+ to the Eu3+ dopant ions in the double doped samples obliterating the green emission from the Tb3+ dopant. However, the Ce3+ ions in the Eu3+ and Tb3+ double doped host yielded green emission which has been assigned to charge-transfer between the Ce3+ and Tb3+ ions. The CIE coordinates of the Zn3(PO4)2:Ce3+(2%):Tb3+(2.5%):Eu3+(0.5%) nanophosphor was found to be (0.35, 0.32), which lie in the white light region of the chromaticity diagram and its quantum efficiency was 47%.