Multilevel based analysis of the thermoluminescence of CaSO 4 : RE ( RE = Tm , Dy, Tb, and Sm)

• Published in: Journal of applied physics 2006-02, Vol.99 (4), p.043506-043506-8
• Main Authors: Shinsho, Kiyomitsu, Suzuki, Yuta, Harada, Kazumasa, Yamamoto, Yusuke, Urushiyama, Akio
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2173033

Multitrapping levels feature of thermoluminescent (TL) phosphors of CaSO 4 : RE ( RE = Dy , Tb, and Sm) were analyzed using a variable heating rate method (including extremely slow heating rates of 0.001 ° C s − 1 ), the postannealing method, and the analysis of TL decay curves using x-ray induced luminescence (XIL) spectroscopy after x-ray excitation was cut off at temperatures between 100 and 240°C. All the data confirmed the multilevel feature of the TL levels. The ranges of activation energies E of these components in the main glow were determined to be (a) 1.64-2.03 eV for CaSO 4 : Dy , (b) 1.66-2.01 eV for CaSO 4 : Tb , and (c) 1.66-2.00 eV for CaSO 4 : Sm . The frequency factor s was determined to be 10 19 s − 1 for all components of the phosphors. The previously reported TL properties of the CaSO 4 : Tm phosphor were reinvestigated using the XIL decay analysis. Assuming that the most populated level is located at the center of the main glow, the four phosphors have similar E values of ∼ 1.8 eV . The present results imply that the multicomponent TL properties of rare-earth-doped CaSO 4 phosphors are characterized by a lattice of CaSO 4 involving defects introduced around RE 3 + ions, and the glow curve properties are essentially not dependent on the rare-earth species introduced.