New melilite (Ca,Sr,Ba)4MgAl2Si3O14:Eu2+ phosphor: structural and spectroscopic analysis for application in white LEDs

Abstract

A series of new Eu²⁺-activated melilite-structured phosphor compounds was developed through solid-state reactions. The structural and spectroscopic properties of the phosphors were analyzed; all phosphors showed emissions in the blue to green regions of visible light. All developed compounds showed asymmetric broad-bands with shoulders on the lower-energy sides. The spectroscopic parameters of Eu²⁺ emission in the host compound were estimated and their correlation with the chemical composition of the phosphor was verified. The luminescence mechanism in the phosphors was analyzed through luminescence decay measurements. The broad emission band in the developed compound, due to transitions in the 4f⁶5d–4f⁷ levels of Eu²⁺, was found to be ideal for application in solid-state lighting devices. The feasibility of the compound as a potential white LED phosphor was demonstrated by fabricating a white LED with excellent emission properties.