Persistent luminescence in the self-activated K2Zr(BO3)2

Abstract

This study reports a cyan emitting self-activated persistent phosphor K₂Zr(BO₃)₂. The material is synthesized by solid state reaction method. The persistent phosphor was characterized in detail by X-ray powder diffraction, diffuse reflectance, photoluminescence, persistent luminescence and thermoluminescence spectra. After UV irradiation, the K₂Zr(BO₃)₂ phosphor shows a cyan persistent luminescence dominating at ∼485 nm. Both the fluorescence and persistent luminescence are due to charge transfer emission from the central zirconium ion to oxygen in the ligand. The deconvolution of the thermoluminescence curve reveals that there are four traps responsible for the persistent luminescence. The depth of the dominant trap is 0.66 eV. Based on experimental results, the trapping and detrapping processes of the charge carriers are discussed. A rudimentary energy level scheme was proposed to explain the mechanisms of persistent luminescence as well as photoluminescence.