Photoluminescence, thermoluminescence, and cathodoluminescence of optimized cubic Gd2O3:Bi phosphor powder

Abstract

Cubic Gd2 − xO3:Bix phosphor powders were prepared with a combustion method and the effect of different annealing temperatures and dopant concentration on the photoluminescence (PL), thermoluminescence (TL), and cathodoluminescence (CL) were investigated. A single-phase cubic crystal structure with the Ia3¯ space group was formed. The average crystallite size increased and decreased, respectively, with an increased annealing temperature and an increased Bi3+ doping concentration. Absorption bands at 250, 275, and 315 nm were observed due to 4f-4f transitions of the Gd3+ ions and at 260, 335, and 375 nm due to the excitation of Bi3+ ions. The emission was obtained from two centers associated with the substitution of the Gd3+ ions with Bi3+ ions at the two different sites in the crystal lattice of Gd2O3 (with a point symmetries C2 and S6). The TL glow curves of the UV-irradiated samples showed a low temperature peak at about 364 K and a high temperature peak at 443 K for all the samples. The surface and CL stability during electron irradiation was monitored. The CL emission of the Gd2O3:Bi was stable after removal of surface contaminants. The phosphor might be usable for solid state lighting and displays due to its broad blue-green emission.