Facile ultrasound route for the fabrication of green emitting Ba2SiO4:Eu2+ nanophosphors for display and dosimetric applications

Abstract

A series of Eu2+ (1–5mol%) activated Ba2SiO4 nanophosphors were prepared by ecofriendly ultrasound assisted sonochemical route using Epigallocatechin gallate (EGCG) extract as bio-surfactant. The obtained nanophosphors were well characterized by Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) etc. The average crystallite size was estimated using Debye–Scherer's formula and Williamson–Hall (W–H) plots and were found to be in the range 20–32nm. The photoluminescence excitation spectrum exhibited two broad bands around 330 and 370nm ascribed to the transitions of Eu2+ from 4f-ground state to 5d-excited state. The emission spectra showed broad band around 505nm wavelength ascribed to 5d→4f allowed transition of Eu2+ ions. Thermoluminescence (TL) of Eu2+ doped Ba2SiO4 nanophosphors were investigated using γ-irradiation in the dose range1–6kGy at a warming rate of 5°Cmin−1. The phosphors show a well resolved single glow peak at ∼175°C. The TL intensity of 155°C glow peak increase linearly with γ-dose and room temperature fading was ∼76% which was highly useful in radiation dosimetry. The kinetic parameters (E, s) were estimated and the results were discussed. The chromaticity co-ordinates of all the prepared phosphors were located in green region, as a result Eu2+ activated Ba2SiO4 was a promising single phased phosphor for WLEDs.