Crystal structure and luminescence property of a novel blue-emitting Cs2xCa2xGd2(1−x)(PO4)2:Eu2+ (x = 0.36) phosphor

Abstract

A novel blue-emitting double-phosphate phosphor Cs_0.72Ca_0.72Gd_1.28(PO₄)₂:Eu²⁺ was synthesized by the sol–gel method, and the structure and luminescence properties were investigated in detail. The crystal structure and chemical composition of Cs_0.72Ca_0.72Gd_1.28(PO₄)₂ matrix was analyzed and determined based on Rietveld refinements and phase and chemical composition analysis. The composition-optimized Cs_0.72Ca_0.72Gd_1.28(PO₄)₂:Eu²⁺ exhibited strong blue light, peaking at 462 nm upon excitation at 365 nm with the CIE coordinates of (0.139, 0.091). The quenching concentration of Eu²⁺ in the Cs_0.72Ca_0.72Gd_1.28(PO₄)₂ phase was about 0.01 and attributed to the dipole–quadrupole interaction. The thermally stable luminescence properties, fluorescence decay curves and diffuse reflectance spectra of Cs_0.72Ca_0.72Gd_1.28(PO₄)₂:Eu²⁺ phosphors are also discussed, all of which indicate that the Cs_0.72Ca_0.72Gd_1.28(PO₄)₂:Eu²⁺ phosphor is a promising phosphor for application in white-light UV LEDs.