Calculation of the activation energy in a continuous trap distribution system of a charoite silicate using initial rise and TL glow curve fitting methods

The blue thermoluminescence (TL) emission of a complex charoite silicate [K4NaCa7Ba0.75Mn0.2Fe0.05(Si6O15)2(Si2O7)Si4O9(OH)·3(H2O)K4NaCa7Ba0.75Mn0.2Fe0.05(Si6O15)2(Si2O7)Si4O9(OH)·3(H2O)], exhibits a continuum in the trap structure similar to that observed in other natural materials; i.e., the glow curve, that consists of a single broad peak at 350∘C, continuously shifts towards higher temperatures when the sample is preheated up to increasing temperatures. This behaviour could be attributed to the charoite strained structure including possible non-bridging oxygen, silicon vacancy–hole centres and Si–O bonding defects which seem to be responsible for this UV–blue emission typical of stressed silicates. The calculation of the activation energy from the TL glow curve performed by the initial rise and the TL glow curve fitting methods are fairly well correlated. The evolution of both the activation energy values and the parameters describing the width of the exponential distribution tends to get larger when increasing the annealing temperatures owing to the emptying of the shallower energy traps.