Evaluation of kinetic parameters of traps in thermoluminescence phosphors
Department of Physics, Rhodes University, P.O. Box 94, Grahamstown, 6140, South Africa; Physics Department, University of Ibadan, Ibadan, Nigeria; Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria
A method for evaluating trap depth E, order of kinetics b and frequency factor s from a thermoluminescence (TL) glow peak has been developed. The method is based on using intensities and temperatures at any three points on the glow peak. Unlike similar techniques that provide no expression for frequency factor, the present formulation provides such an expression. The expression does not require knowledge of the temperature at which maximum intensity occurs, a parameter not usually known accurately from experimental glow peak data. For the method, it is found that use of points in the ascending part of the glow peak where the intensities are less than 10% maximum intensity gives parameter values closest to the true ones. Possible reasons for getting less accurate results when points are taken beyond this region are discussed. Values of the activation energy calculated using the present technique were always close to the true value. However, the frequency factor only approaches the true value as the dose given to the sample approaches saturation. When the three data points are selected in the initial-rise region, the equation for evaluating E in the method described in this paper becomes a two-point version of the initial-rise method. The advantage of the present technique over the initial-rise method is that it also gives b and hence s. The method is used to analyse the TL glow curve of a gamma-irradiated sample from Ijero-Ekiti, Nigeria. © 2006 Elsevier Ltd. All rights reserved.
Frequency factor; Initial-rise method; Kinetic parameters; Thermoluminescence phosphors; Traps; Two-point version; Activation energy; Dosimetry; Gamma rays; Saturation (materials composition); Thermal effects; Thermoluminescence; Phosphors