Influence of magnesium concentration on thermal stability in LiF:Mg,Cu,P

Synthesis and dosimetry features of novel sensitive thermoluminescent phosphor of LiF doped with Mg and Dy impurities

Lithium fluoride doped with Mg and Dy was fabricated for the first time using melting method. The optimum concentrations of impurities and thermal treatment were studied to achieve high thermoluminescence (TL) sensitivity. TL sensitivity of the fabricated phosphor is close to that of TLD-100 powder. T_m-T_stop technique was used to identify the number of overlapped TL glow peaks. Initial rise, isothermal decay and computerized glow curve deconvolution (CGCD) methods were applied to obtain kinetic parameters of the prepared TL material. Three component glow peaks were distinguished at temperatures 395, 448 and 510 K. Other TL properties such as fading, linearity of dose response and reusability are also presented and discussed.

Comparative studies on radioluminescent and thermoluminescent spectra of LiF:Mg,Cu,P and LiF:Mg,Cu,Si

The influence of various annealing treatments on radioluminescent (RL) and thermoluminescent (TL) spectra of LiF:Mg,Cu,Si and LiF:Mg,Cu,P was investigated. The TL and RL emission bands for LiF:Mg,Cu,P are not the same; however, the emission band peaking at ∼383 nm is predominant in the TL and RL emission for LiF:Mg,Cu,Si. With the increase in annealing temperatures in the range of 240-300°C, for LiF:Mg,Cu,P, the intensity of TL decreases much more rapidly than that of RL. For LiF:Mg,Cu,Si, the area ratios of the two bands of RL and TL remain constant within experimental errors. It suggests that there is a significant decrease in the concentration of recombination centres in LiF:Mg,Cu,P after the annealing, in addition to the decrease in trapping centres, the recombination centres for main TL emission and RL emission in LiF:Mg,Cu,Si are the same, and the recombination centres for TL emission and RL emission in LiF:Mg,Cu,P are not the same. P is a more effective dopant than Si.

The effect of Mg, Cu and P impurities on dose response of LiF:Mg,Cu,P phosphors: simulation versus experiments

In this research, the effect of magnesium (Mg), copper (Cu) and phosphorus (P) impurities on dosimetry response of LiF:Mg,Cu,P phosphors is studied experimentally and by the simulation procedure. In the experimental procedure, LiF:Mg,Cu,P phosphors in the powder form were synthesised by chemical co-precipitation method. After annealing at 250°C for 10 min, known amounts of powder were exposed to gamma doses from 0.2 to 1 Gy. The activation energy of the electronic traps for the dosimetric peak at 150°C in LiF:Mg,Cu,P crystalline lattice obtained was 0.69 eV. In the simulation study, the role of stated dopants on electronic and structural properties of LiF crystalline lattice is investigated with the WIEN2 K Code. The activation energies of the electronic and hole traps for the dosimetric peak at the same temperature in LiF:Mg,Cu,P crystalline lattice obtained are 0.75 and 3.1 eV, respectively. It is shown that the experimental results are in agreement with simulation results.

Further studies on the role of dopants in LiF:Mg,Cu,Si thermoluminescent material

The 3-D thermoluminescence spectra and glow curves of LiF:Mg,Cu,Si, LiF:Mg,Cu, LiF:Mg,Si and LiF:Cu,Si with low concentrations of Mg and Cu were measured and were compared with those with high concentrations to investigate further the role of dopants in LiF:Mg,Cu,Si material. The shape of glow curves of the four samples is similar; however, LiF:Cu,Si sample had no Mg dopant. It is concluded that the TL emission to be from self-trapped excitons in LiF, and this emission could be enhanced and altered by Mg, Cu and Si dopants in LiF:Mg,Cu,Si; all three dopants are necessary to obtain the bright TL emission and may be involved in the luminescence process; Mg seems to be the most essential dopant and Cu is involved in the trapping although the role of Mg dominates; both Cu and Si play a role in the main emission process and Cu also plays a role in reducing the emission around 610 nm.