Main Thermoluminescence Glow Peak Research Articles

Detailed luminescence (RL, PL, CL, TL) behaviors of Tb3+ and Dy3+ doped LiMgPO4 synthesized by sol-gel method

The un-doped, Tb3+ and, Dy3+ doped LiMgPO4 phosphors were successfully synthesized by the sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the light-emitting phosphors. The XRD spectra verify the phase formation of samples. The luminescence properties were analyzed by radioluminescence (RL), photoluminescence (PL), cathodoluminescence (CL) and, thermoluminescence (TL) spectra. Also, the effect of Tb3+, Dy3+ ions in LiMgPO4 was determined on the luminescence intensity in detail.The RL spectrum of un-doped LiMgPO4 consists of two broad emission bands in the 310–450 nm and 575–850 nm range. The maximum intensities of these bands were observed at 360 nm and 655 nm. The emission spectrum of Dy3+ doped LiMgPO4 under X-ray excitation show characteristic emissions of Dy3+ corresponds to 4F9/2→6Hj transitions. In addition to the 5D4→7Fj (j:6–1) transitions of Tb3+ doped LiMgPO4 phosphor, strong emissions derived from 5D3→7Fj (j:6–3) transitions were observed in the blue region. Also, these blue emissions were seen at RL, PL and, CL spectra. The optical absorption spectra were recorded and the energy band gaps were calculated 3.62 eV, 3.30 eV and, 4,01 eV for un-doped, Dy3+ and, Tb3+ doped LiMgPO4 phosphors, respectively. The phosphors irradiated with UV (254 nm) light. The main TL glow peak was observed at 288 °C for the Dy3+ doped phosphor, and the peaks at 198, 283 °C were observed for the Tb3+ doped phosphor.

Thermoluminescence characterization of nanocrystalline powder of SrSO4:Sm exposed to gamma radiation for dosimetric applications

Dosimetry properties of nanocrystalline SrSO4:Sm powders prepared via a co-participation method, were studied. X-ray diffraction, energy dispersive X-ray spectroscopy and Field emission scanning electron microscopy (FE-SEM) were used to investigate the structure, composition and morphology of nanocrystalline SrSO4:Sm powders. The nanocrystalline SrSO4:Sm powders had the orthorhombic crystal structure. FE-SEM image showed polygonal structure of particles with an average size of particles 0.2 μm. The thermoluminescence (TL) measurements for different concentration of samarium were done after gamma irradiation. TL glow curves showed the main glow peak at 370 °C. The maximum intensity of the TL glow curves for SrSO4:Sm was obtained with 0.05mol% concentration of Sm. Then, due to its high intensity glow curve, it was selected as the main sample. Furthermore, its dose-response, energy-response, and fading were studied in detail. Nanocrystalline SrSO4:Sm(0.05 mol%) powder had a linear dose-response approximately between 10Gy and 3 kGy. It showed energy dependence for low energy photons and its fading was less than 20% after 37 days. The X-ray excited luminescence (XEL), and TL were examined. The kinetic parameters were calculated by using the various TL analysis methods and OriginPro 8 software. The results showed the main TL glow peak obeyed second order kinetics.

X-ray irradiated thermo- and radioluminescence, structural and thermal characterization of septarian (powder&bulk) from Madagascar

The luminescence properties of septarian have been investigated for the first time in this study, which has been the subject of many studies in both geological and geophysical fields. This sediment with a calcium carbonate structure exhibited high luminescence properties with X-ray excitation. The radioluminescence (RL) and thermoluminescence (TL) properties were investigated as well as their structural (FT-IR, XRD), morphological (SEM), thermal (TG-DTA) and absorption (UV-Vis-NIR) properties of this sediment. The broad RL peak of septarian was observed at 640 nm. There was a significant increase in the RL intensities of the sifted samples compared with the bulk sample. The TL glow curves of septarian irradiated with X-rays exhibited intense main TL glow peak having the maximum temperatures at 116 °C and about 390 °C with a heating rate of 2 °C/s. Also; the TL kinetic parameters were reported; activation energy (E), frequency factor (s) and the order of kinetics (b) of the first peak have been determined in detail by using peak shape (PS) and Computerized Glow Curve Deconvolution (CGCD) methods. SEM and EDS analysis were performed for the two different layers of septarian. The light colored side with the amorphous structure of the sample has more impurities (such as Fe, Al, Zr, K) than the crystallized and darker side.

Determination of thermoluminescence kinetic parameters of white and blue chalcedony exposed to X-ray irradiation

The study reveals the thermoluminescence (TL) properties of white and blue chalcedony minerals which this mineral mined two different regions (Edirne and Eskişehir, respectively) of Turkey. With the help of various characterization techniques (such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR)), the gem-quality of the samples was tested. The TL glow curves of the samples irradiated with X-rays show intense main TL glow peak having the maximum temperatures at 100 °C and 121 °C with a heating rate of 2 °C/s, respectively. The TL kinetic parameters of the samples are reported here for the first time. Activation energy (E), frequency factor (s) and the order of kinetics (b) of these peaks have been determined in detail by using various heating rates (VHR) and peak shape (PS) methods and verified by Computerized Glow Curve Deconvolution (CGCD). The CGCD method was used to determine the number of peaks associated with the TL glow curves. The values of E calculated with these three methods are a good agreement.

Thermo-luminescence kinetic parameters of γ-irradiated Sr4Al14O25:Eu2+, Dy3+ phosphors

In this paper, we present a detailed investigation of the thermo-luminescence (TL) kinetics of the long afterglow phosphor, Sr4Al14O25:Eu2+,Dy3+, synthesized by the combustion method. Kinetic parameters such as the activation energy (Eα), the frequency factor (s) and the order of kinetics (b) were calculated using Chen's formulism. The crystalline structure of the phosphor was examined using X-ray powder diffraction and transmission electron microscopy. The average particle size was found to be in the range of 45–52 nm. The optimum dopant concentrations were Eu (1 mol%) and that of Dy (2 mol%). The TL response of the phosphor was monitored after the samples were irradiated with a γ-dose using a 60Co source in the 20-800 Gy range. A broad TL peak, (stretching from 328 to 410 K) with a maximum at 368 K was observed. With increasing irradiation dose, the main peak shifts toward higher temperatures. Symmetry factor calculations show that the main TL glow peak obeys second-order kinetics, which could be attributed to the creation of deep level traps. This means that γ-ray irradiation greatly affects the distribution of traps in the Sr4Al14O25:Eu2+,Dy3+ phosphor. The phosphor showed a linear response with γ-dose.

Thermoluminescence behaviour of KCL1−xBrx:Pb2+ exposed to gamma radiation

The thermoluminescence (TL) behaviour of solid solutions of lead doped KCl(1-x)Br(x) (X = 0.02, 0.35, 0.50, 0.65, 0.85, 1) mixed crystals exposed to gamma radiation at different doses from 60Co is reported. The TL glow curves of KCl(1-x)Br(x):Pb2+ crystal exposed in the range of 0-140 Gy is strongly dependent on composition X. The maximum temperature of the main TL glow peak was found to shift towards lower temperatures as composition X increased and a significant enhancement of the TL efficiency in KCl(1-x)Br(x):Pb2+ was found for X = 0.50 which is attributed to an increase in the vacancy concentration of the mixed halides at middle composition. The participation of the F-centre in the TL phenomenon particularly related to the main TL glow peak observed in mixed samples was also confirmed.

Optically and thermally stimulated luminescence characteristics of MgO:Tb3+

In this paper main optically stimulated luminescence (OSL) and thermoluminescence (TL) characteristics are presented of a newly synthesised material MgO doped with terbium (Tb) developed at the Institute of Nuclear Science, Vinca. A thermally stimulated emission spectrum showed the characteristic lines of Tb3+ in a wide range of wavelengths. The TL sensitivity of the main TL glow peak at 315 degrees C is 1.7 times higher than the TL of Al2O3:C. The highest OSL sensitivity was obtained under green lamp (500-570 nm) stimulation. The fast component in the OSL decay curve is 2.4 times faster than Al2O3:C. The OSL signal is linear with dose up to 10 Gy. The lower limit of detection was found to be 100 microGy. These first results show that the newly synthesised material has some promising properties for the application in radiation dosimetry.

Luminescence properties of Sm3+ in strontium tetraborate for assessment of electron beam dosimetry

In this article, thermoluminescence (TL) studies on a Sm3+ doped SrB4O7 compound irradiated by an electron beam are reported for the first time. The polycrystalline powder samples of SrB4O7:Sm phosphor were prepared by a solid-state reaction in air at high temperature, and the TL glow curves and TL emission spectra after electron beam irradiation were studied from 50 to 250 kGy dose range. The TL studies of the Sr0.93Sm0.07B4O7 sample show the main TL glow peak at 224 °C, which has a great stability for a long time. The trap parameters, namely, the activation energy (E), the order of kinetics (b) and the frequency factor (s) of the main peak were determined using glow curve shape (Chen's) methods. The distributions of traps produced by the irradiation by an electron beam can be altered greatly by the change of the concentration of Sm3+ ions in the SrB4O7 host. Then, all peak temperatures shift to higher temperatures which this will be favorable for better TL output. The TL-dose response of the SrB4O7:Sm polycrystalline powder sample to electron beam radiation in the range from 50 to 250 kGy for radiation processing dose levels is almost linear. The experiment results showed that SrB4O7:Sm has a potential use as a material for electron beam thermoluminescence dosimetry.

Thermal recovery processes between 80 and 300 K on x-irradiated NaCl:Mn2+

The thermal recovery processes after 80 K irradiation of NaCl:${\mathrm{Mn}}^{2+}$ have been investigated by using thermoluminescence (TL), optical absorption, and electron paramagnetic resonance (EPR). A main TL glow peak (II) is observed at about 170 K, both in pure and doped samples (the kinetics being, respectively, second and first order). It has been associated to the recombination of mobile ${V}_{k}$ centers with electron-trapped centers. For doped samples these electronic-centers have been identified as ${\mathrm{Mn}}^{0}$ $B$ centers; whereas for pure samples they are suggested to be ${F}^{\ensuremath{-}}$ centers. The kinetics of the peak as well as the change in the temperature of its maximum with manganese concentration can be accounted for, by using the theory of diffusion-limited reactions. The activation energy for the diffusion of ${V}_{k}$ centers has been found to be 0.37 eV. For doped samples, two other glow peaks at 108 K (I) and 222 K (III) are observed. Possible models for them have been advanced; in particular peak III seems to be associated to the thermal release of holes from ${V}_{F}$ centers. At variance with the data above room temperature, no correlation has been found between any of the TL peaks and an annihilation step in the $F$-center concentration.

銅と銀で活性化したLi<sub>2</sub>B<sub>4</sub>O<sub>7</sub>TLD

Lithium borate (Li2B4O7) is known as one of the most promising thermoluminescence materials because of its low dependence on photon energy. A new phosphor, Li2B4O7 activated with copper and silver (0.02_??_Cu, 0.02_??_Ag), has been developed and found to have the following thermoluminescence characteristics.(1) Its thermoluminescence emission bands lie in the near ultraviolet region; a dominant peak appears at 368 mμ (by Cu) and another smaller one at 268 mμ.(2) The main thermoluminescence glow peak appears at 185°C (by Ag), and another smaller one at 110°C.(3) The thermoluminescence output detected by a widely used photomultiplier (1P21) is about 3 times larger than that of Li2B4O7: Mn, and the expoure response is linear in an exposure range from 10 mR to 300R.(4) Fading is less than 9% in 2 months.

The application of thermoluminescence theory to natural semiconducting diamond

The main thermoluminescence glow peak at ~ 250°K in natural semiconducting diamond has been analysed by methods proposed by several authors, using the model of the thermoluminescence process developed in the preceding paper as a guide. Kinetic equations appropriate to two conditions of recombination are developed and discussed in the light of the recombination processes in natural semiconducting diamond. A summary of several methods of analysis is given. The various methods are then applied in turn to the 250°K glow peak. The method of initial rise is shown to be appropriate to the model of trapping and recombination given in the preceding paper, and gives a value 0.35 ± 0.02 eV for the trap depth. Halperin and Braner's method for the trap depth is unsuitable owing to the high value of their correction term 2 kT m/ E, although their analysis suggests that the order of the kinetics changes from nearly 1st to nearly 2nd as the glow progresses. The methods of Grossweiner, Keating and Luschik apply only when 1st order processes are selected. An estimation of the trapping cross-section gives S T ~ 10 -20 cm 2.