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

Abstract

The blue thermoluminescence (TL) emission of a complex charoite silicate [K 4 NaCa 7 Ba 0.75 Mn 0.2 Fe 0.05 (Si 6 O 15 ) 2 (Si 2 O 7 )Si 4 O 9 (OH) · 3(H 2 O)], 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.

Thermo- and cathodoluminescence properties of lepidolite

“…Consequently, there is the typical shift of the maximum peak towards higher temperatures and a change in the shape and intensity of the TL distribution depending on thermal pre-treatment that could engage consecutive breaking and linking of bonds of Al-O, Fe-O including dehydroxylation and redox reactions in the material. Table 2 shows the activation energy, E, calculated for both, natural (non-irradiated) lepidolite preheated at different temperatures (T stop ) in the range 275 -460 C, and 1 Gy irradiated samples preheated in the range 75 -130 o C by means of the initial rise (IR) method [33]. In both cases, the maximum moves towards higher energies when increasing the annealing temperature due to the emptying of these traps.…”

Determination of Trapping Parameters of Tl2In2S3Se Layered Single Crystal by Thermoluminescence

“…As a result of this, it is observed that the mean activation energy of the trap states increased from 23 to 100 meV with increasing temperature from 10 to 22 K as seen in inset 1 of Figure 4. It is an expected result since when illumination temperature increased, shallow trap states became vacant so while illumination temperature increased activation energy increased and the TL intensity decreased . Furthermore, from the areas ( S 0 ) of two subtracted sequential TL glow curves, the released charge from the trap states were evaluated.…”

The High-Temperature Behavior of Charoite

“…(v) The charoite composition has silicon and cations such as K and Ca, but little Al; for this reason, we minimize the importance of [AlO 4 ]°-alkali centers producing the blue emission at ~400 nm. These processes, observed in other hydrolyzed minerals, are interpreted as being due to a continuum in the trap distribution or to the existence of a tunneling recombination process in coincidence with the dehydroxylation temperature of charoite (Correcher et al 2008).…”