Optimization luminescence properties and energy transfer mechanism with temperature change of Sr3Ga2O5Cl2:Eu3+, Bi3+ phosphors

Abstract

A red phosphor of Eu3+, Bi3+ co-doped Sr3Ga2O5Cl2 is synthesized by solid-state reaction for the first time. The XRD Rietveld refinement presents that the compound crystallizes in a monoclinic crystal system with space group C22−P21. Under the excitation of 393nm, Sr3Ga2O5Cl2:Eu3+ shows an efficient red emission with the dominated peak at 618nm (5D0–7F2). With the introduction of Bi3+, the emission intensity of Eu3+ rapidly increases due to the energy transfer from Bi3+ to Eu3+. The dominated emission peak shifts from 618 to 703nm (5D0–7F4), implying that the crystal environment of Eu3+ in Sr3Ga2O5Cl2 possibly becomes serious distortion. With the increase of temperature from 20 to 250°C, the Eu3+ single doped Sr3Ga2O5Cl2 reveals an excellent thermal property, but the thermal stability of Eu3+, Bi3+ co-doped Sr3Ga2O5Cl2 appears severe degradation, which indicate that a complicated energy transfer process possibly occurs between Eu3+ and Bi3+. Based on the configurational coordinate diagram, the phenomenon can be reasonably explained.