Kinetic characterization of MgB4O7:Dy,Na thermoluminescent phosphor

Dosimeters of MgB4O7 doped with Dy and Na have many valuable features such as high sensitivity, tissue equivalence, low fading, non-requirement of annealing and insensitivity to light. Thermoluminescence studies of Dy and Na doped MgB4O7 samples showed that a glow emission peaked at about 195 degrees C. In this study, the trapping parameters associated with the main dosimetric peak, namely at 195 degrees C, of Dy and Na doped MgB4O7 are investigated. Isothermal luminescence decay, glow curve shape, initial rise (linear regression) and T-m - T-stop methods were used. We report the results on the kinetic behaviour and activation energy determination of the peak occurring at 195 degrees C with a moderate heating rate of 2 degrees C s(-1). The average activation energies obtained by the isothermal luminescence decay method, glow curve shape method and initial rise method are calculated to be 1.03 eV, 0.95 eV and 0.89 eV, respectively. The methods mentioned above indicate that the dosimetric peak may consist of one or more second-order components. The frequency factors obtained by the three methods are 3.5 x 10(10) s(-1), 1.6 x 10(9) s(-1) and 3.4 x 10(8) s(-1),respectively. Results obtained using all these methods are compared and discussed.