A novel Eu3+/Eu2+ co-doped MgSrLa8(SiO4)6O2 single-phase white light phosphor for white LEDs

Abstract

A novel MgSrLa_8−x(SiO₄)₆O₂:xEu (MSLSO:xEu) phosphor was synthesized through a high-temperature solid-state reaction. The crystal structures, luminescent properties, fluorescence decay time, and oxygen vacancies were investigated systemically. XRD analysis shows a typical oxyapatite structure with the space group P6₃/m. Europium can enter crystal matrices simultaneously in the form of Eu³⁺ and Eu²⁺ and occupy nonequivalent crystallographic positions in a lattice, thus forming various optical centers. Under ultraviolet light excitation, the phosphors simultaneously show the blue-green emission of Eu²⁺ and the green-yellow-red emission of Eu³⁺. The optimal doping content of Eu is 7.5 mol% (x = 0.075). White light can be realized with a CIE coordinate of (0.3664, 0.3260) by adjusting the concentration of Eu. The lifetimes of Eu³⁺ and Eu²⁺ in this study are considerably longer than those in other references. The results suggest that the MSLSO:Eu²⁺/Eu³⁺ (0.075) phosphor is a promising candidate for white LEDs.