Thermoluminescence mechanism of dysprosium-doped β-tricalcium phosphate phosphor

beta-Tricalcium phosphate (beta-Ca-3(PO4)(2), beta-TCP) and dysprosium-doped beta-tricalcium phosphate (beta-Ca-3(PO4)(2):Dy, beta-TCP:Dy) phosphor were synthesized. Powder X-ray diffraction, electron spin resonance (ESR), photoluminescence (PL), and thermoluminescence (TL) were measured. Although no PL and TL could be identified for undoped beta-TCP, PL and TL were observed for beta-TCP:Dy phosphor. The TL emission peaks are assigned to the f-f transitions of the Dy3+ ion which were found to be the same as those of the PL of beta-TCP:Dy phosphor. A detailed analysis of the TL peak shape can give information on the trap depth (activation energy epsilon), indicating the trap depth of epsilon = 1.1 eV from Hoogenstraaten's method. We succeeded in detecting the stable trapped hydrogen atom in the X-ray-irradiated beta-TCP:Dy phosphor at room temperature for several months using ESR. The TL phenomenon of beta-TCP:Dy phosphor is related with these trapped hydrogen atoms. (C) 2004 Elsevier B.V. All rights reserved.