Color-tunable light emission of SrLa4-x-ySi3O13:xTb3+, yEu3+ phosphors by energy transfer process for warm white LEDs

SrLa 4-x-y Si 3 O 13 : xTb 3+ , yEu 3+ phosphor was prepared by high temperature solid-state method. The luminescent centers of Eu 3+ and Tb 3+ occupying La 3+ lattice sites in hosts were confirmed by Rietevld refinement method. The phenomenon of self-cross-relaxation energy transfer is observed between Tb 3+ ions from 5 D 4 - 7 F J to 7 F 6 - 5 D 4 transition. Additionally, the direction of energy transfer (ET) was observed from Tb 3+ to Eu 3+ ions, and ET efficiency became more efficient as the concentration of activator increases. The type of ET between Tb 3+ and Eu 3+ ions was demonstrated to be the dipole-dipole mechanism. The multi-color lights were realized covering the green to red visible region by the route of energy transfer. Furthermore, the decrease of Eu 3+ emission intensity resulting from thermal quenching can be effectively compensated by Tb 3+ →Eu 3+ ET. The excellent luminescent properties and thermal stability show this phosphor to be a promising candidate for white LEDs.