The Effects of Rare-Earth Co-Dopants on Green Long-Lasting Phosphorescence and Thermoluminescence Properties of Ca8Mg ( SiO4 ) 4Cl2 : Eu2 + , RE3 +

Abstract

A series of green long-lasting phosphorescence materials was systematically investigated by long-lasting phosphorescence and thermoluminescence spectra. The green phosphorescence predominates at 502 nm due to the transition of the ion. It strongly depends on the co-doped rare-earth ion, and its performance decreases in the order ; for the Yb ion, the phosphorescence is totally quenched. The thermoluminescence properties show that there are generally four peaks around 330, 370, 435, and 470 K in the temperature range of 293–577 K, associated with the foreign defects due to the aliovalent substitution of rare-earth ions. The relationship of the long-lasting phosphorescence and thermoluminescence properties show that the difference in trap depth and the density of charge trapping centers and trapped charges, associated with thermoluminescence characteristics in the temperature range of 300–400 K, is responsible for the regular variation in the green long-lasting phosphorescence. The thermoluminescence spectrum of is fitted by the general kinetic model. The most appropriate trap depth in the present host is estimated to be around 0.8 eV, and the kinetic-order parameter is 1.14.