Thermoluminescent and stuctural properties of BaAl₂O ₄:Eu²⁺,Nd³⁺,Gd³⁺phosphors prepared by combustion method

BaAl₂O₄:Eu²⁺,Nd³⁺,Gd ³⁺ phosphors were prepared by a combustion method at different initiating temperatures (4001200°C), using urea as a comburent. The powders were annealed at different temperatures in the range of 4001100°C for 3 h. X-ray diffraction data show that the crystallinity of the BaAl₂O ₄ structure greatly improved with increasing annealing temperature. Blue-green photoluminescence, with persistent/long afterglow, was observed at 498 nm. This emission was attributed to the 4f⁶5d¹4f ⁷ transitions of Eu²⁺ ions. The phosphorescence decay curves were obtained by irradiating the samples with a 365 nm UV light. The glow curves of the as-prepared and the annealed samples were investigated in this study. The thermoluminescent (TL) glow peaks of the samples prepared at 600°C and 1200°C were both stable at ∼72°C suggesting that the traps responsible for the bands were fixed at this position irrespective of annealing temperature. These bands are at a similar position, which suggests that the traps responsible for these bands are similar. The rate of decay of the sample annealed at 600°C was faster than that of the sample prepared at 1200°C.