Effects of heat-treatment on photoluminescence properties of MgAl2O4:Eu3+ red phosphors synthesized by a solution combustion method

Abstract

Abstract To investigate the influence of annealing temperature on the structure and photoluminescence property, 5% wt. Eu3+ doped MgAl2O4 ceramics have been synthesized by a solution combustion reaction and thermally treated at 700, 800, 900, 1000, 1100, and 1200 °C. Powder XRD indicate that pure spinels were synthesized and the crystallinity increased with the increase of the heat treatment temperature. Low temperature heat capacities of these phosphors were measured and the data were fitted by T3 Debye model. The obtained Debye temperature of sample show positive relationship with the calcine temperature. Our results suggest that the heat treatment improves the crystallinity and decreases the structure defects of MgAl2O4:Eu3+. The SEM shows spongy structure of the particles is dependent on the calcine temperature. These phosphors exhibit hypersensitive red emission peaking at 613 nm, which corresponds to the electric-dipole 5D0 - 7F2 transition of Eu3+ ions. Comparison between the excitation and emission spectra has shown modification of their spectroscopic characteristics. The MgAl2O4:Eu3+ calcined at 900 °C shows the best performance based on the dominant red (5D0-7 F2) emission and the effective emission excited by near-UV 394 nm show potential applications in solid state lighting.