Thermoluminescence Glow Peak Research Articles

Combustion synthesis and characterization of phosphor KSr4 (BO3)3:Dy3+

The polycrystalline sample of KSr4 (BO3)3:Dy [KSBD] was successfully synthesized by novel solution combustion synthesis and has been studied for its thermoluminescence (TL) characteristics. The TL glow curve of the compound was composed of two peaks around 183°C and 314°C. The peaks are deconvoluted to determine kinetic parameters i.e. trap depth or activation energy and frequency factor from the glow curve by using peak shape method. Though the Zeff of KSBD material is very high, TL sensitivity of the phosphor was found to be as responsive as commercial phosphor TLD-100. Fading effect, variation of TL glow peak intensity with dose also been studied. The emission spectra monitored for 350nm excitation shows the characteristic emission of Dy3+ ions.

Investigation of thermoluminescence characteristics of gamma irradiated phlogopite mica

The present paper investigates the thermoluminescence (TL) characteristics of phlogopite mica irradiated with gamma rays in the dose ranges from 5kGy to 40kGy. It has been found that at all gamma doses, TL glow curve of phlogopite mica shows a simple glow curve structure with one broad peak around 400K temperature. There is no shift in peak temperature with increase in gamma dose which clearly indicates that TL glow peaks are of first order kinetics. The TL intensity increases linearly up to 30kGy and then shows saturation up to 40kGy which have been explained using TIM and UNIM model. The effect of different heating rates on the TL intensity, TL glow peak temperature and total glow curve area for 10kGy irradiated phlogopite mica has also been studied. Theoretical analysis of TL glow curves of gamma irradiated phlogopite mica has been done by glow curve deconvolution procedure using computerized Glow Fit software and the trapping parameters of isolated TL glow peaks have also been determined. The simple glow curve structure and the linear TL response to a wide range of gamma doses of phlogopite mica confirm its suitability as an effective thermoluminescent material and explore its potential for tremendous applications in radiation dosimetry.

Photoluminescence and thermoluminescence studies of Tb3+ doped ZnO nanorods

Abstract Here in, the synthesis of the terbium doped zinc oxide (ZnO:Tb3+) nanorods via room temperature chemical co-precipitation was explored and their structural, photoluminescence (PL) and thermoluminescence (TL) studies were investigated in detail. The present samples were found to have pure hexagonal wurtzite crystal structure. The as obtained samples were broadly composed of nanoflakes while the highly crystalline nanorods have been formed due to low temperature annealing of the as synthesized samples. The diameters of the nanoflakes are found to be in the range 50–60 nm whereas the nanorods have diameter 60–90 nm and length 700–900 nm. FTIR study shows Zn O stretching band at 475 cm−1 showing improved crystal quality with annealing. The bands at 1545 and 1431 cm−1 are attributed to asymmetric and symmetric C O stretching vibration modes. The diffuse reflectance spectra show band edge emission near 390 nm and a blue shift of the absorption edge with higher concentration of Tb doping. The PL spectra of the Tb3+-doped sample exhibited bright bluish green and green emissions at 490 nm (5D4 → 7F6) and 544 nm (5D4 → 7F5) respectively which is much more intense then the blue (450 nm), bluish green (472 nm) and broad green emission (532 nm) for the undoped sample. An efficient energy transfer process from ZnO host to Tb3+ is observed in PL emission and excitation spectra of Tb3+-doped ZnO ions. The doped sample exhibits a strong TL glow peak at 255 °C compared to the prominent glow peak at 190 °C for the undoped sample. The higher temperature peaks are found to obey first order kinetics whereas the lower temperature peaks obey 2nd order kinetics. The glow peak at 255 °C for the Tb3+ doped sample has an activation energy 0.98 eV and frequency factor 2.77 × 108 s−1.

Thermoluminescence studies of copper-doped cadmium sulphide nanoparticles with trap depth parameters

In this paper we report the synthesis of CdS:Cu nanoparticles by chemical precipitation. The structure and thermoluminescence (TL) properties of the particles were studied. TL glow curves and kinetic data, for example activation energy, order of kinetics, and frequency factor of the nanoparticles, were determined for different UV exposure times. TL glow curves were recorded for different doses of UV exposure time at a heating rate of 10 ° s−1. TL glow peaks were observed at 241.2, 252.3, and 275.3 °C when the particles were exposed to UV for 5, 10, and 15 min. Kinetic data for the synthesized nanophosphor CdS:Cu were calculated by use of the peak-shape method; trap depth was also calculated, by use of different formulae. XRD results showed the sample has a cubic structure. The average particle size was 35 nm. The Miller indices were also obtained.

Influence of halide flux on the crystallinity, microstructure and thermoluminescence properties of CdSiO3:Co2+ nanophosphor

CdSiO3:Co2+ (1–7mol %) nanophosphors have been prepared via solution combustion method with post calcination at 800°C for 2h for the first time. The formation of expected monoclinic phase was investigated by Powder X-ray diffraction (PXRD) measurements. The effect of different fluxes like NaF, NaCl, NH4F and NH4Cl on the crystallinity, phase and morphology of CdSiO3 was investigated in detail. The crystallinity of the samples can be greatly enhanced by using fluxes rather than increasing the calcination temperature. Scanning electronic micrograph (SEM) image shows that the powder morphologies are highly influenced by flux addition. The addition of 2wt% of fluxes would drastically enhance the crystallinity when NaCl, NH4F and NH4Cl fluxes are used. A well resolved single thermoluminescent glow peak at ∼170°C was recorded for all the samples. Among all the halide fluxes, NaCl flux was found to be the potential one in enhancing the TL peak intensity along with crystallinity.

Structural characterization, thermoluminescence and EPR studies of Nd2O3:Co2+ nanophosphors

Nd2O3:Co2+ (1–4mol%) nanophosphors (15–25nm) have been prepared via low temperature solution combustion method. Scanning electron micrograph (SEM) shows that the product is highly porous in nature. The stokes line in the Raman spectrum at ∼2000cm−1 is assigned to Fg mode and the anti-stokes lines are assigned to a combination of Ag+Eg modes. With increase of Co2+ concentration, the intensity of Fg mode decreases, whereas the combination of Ag+Fg modes completely disappears. Electron paramagnetic resonance (EPR) spectrum exhibits two resonance signals with effective g values at g=2.25 and g=2.03. Thermoluminescence (TL) response of Nd2O3:Co2+ nanopowders with γ dose 0.23–2.05kGy was studied. The activation energy (E) and frequency factor (s) are estimated using Chen's glow peak shape method and obtained to be in the range 0.45–1.67eV and 1.8×104 to 4.0×1012s−1, respectively. It is observed that the TL glow peak intensity at 430K increases linearly with γ dose which is suitable for radiation dosimetry.

Synthesis and dosimetric properties of the novel thermoluminescent CaF2:Tm nanoparticles

Calcium fluoride nanoparticles doped with thulium were synthesized for the first time by using the hydrothermal method. The synthesized nanostructures were characterized by X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The crystallite size of about 40nm was estimated by Scherer's formula. The shape and size of the nanoparticles were also observed by scanning electron microscope (SEM). Tm–Tstop method and computerized glow curve deconvolution (CGCD) technique were employed to obtain the number of component glow peaks and kinetic parameters of the produced phosphor. Three overlapped thermoluminescence glow peaks were identified at 402, 426 and 467K in the complex glow curve of this phosphor. The optimized concentration of Tm impurity was obtained at 0.5mol%. Other thermoluminescence characteristics of this phosphor such as fading, reusability and dose response, reveals superior dosimetry features compared to its microcrystalline counterpart.

Optical bleaching and radiation response of feldspar TL glow peaks separated by using computerized glow curve deconvolution

The thermoluminescence (TL) peaks of feldspar were separated using the computerized glow curve deconvolution (CGCD) method combined with the second-derivative technique and were investigated not only for bleaching with different light sources (blue and infrared) but also for luminescence response to radiation dose. In the results, the TL glow peak was separated into four peaks at 280 °C, 315 °C, 360 °C, and 440 °C. Each separated TL glow peak exhibited two exponential decays in the signal bleached using blue or infrared stimulation. In view of all four separated glow peaks, the bleaching of the first (second) exponential component was faster (slower) for both the blue and the infrared stimulation as the peak temperature increased, and the bleaching of the first (second) exponential component with blue stimulation was faster (slower) than that with infrared stimulation. In addition, we found that with added beta dose, the shapes of the growth curves showed no substantial differences for the separated glow peaks.

Synthesis and thermoluminescence characteristics of gamma and proton irradiated nanocrystalline MgB4O7: Dy, Na

This paper investigates the use of nanocrystalline MgB4O7: Dy, Na thermoluminescent (TL) dosimeter synthesized by the combustion method for the assessment of proton beam and gamma radiation doses, primarily on the shape of the TL glow curves. TEM and XRD studies revealed that the particles were tubular in shape and approximately 50nm in size. The heating rate which affects the thermal quenching as well as the annealing temperature of the material was optimized. Samples in pellet form were irradiated by 150MeV proton beams (1–450Gy) and also with gamma rays (0.1–1000Gy) for comparison. Trapping parameters of proton beam and gamma-irradiated materials were also obtained after deconvolution of the glow curves. In case of gamma-irradiation the nanophosphor showed an intense TL glow peak at 400K and a small peak at 512K, however in case of proton irradiation the nanophosphor showed a peak at 477K and a small shoulder at around 450K. The dose response curve of the nanophosphor for proton irradiation was found to be linear up to 350Gy with a slight supralinearity for higher doses whereas the nanophosphor's gamma dose response was found to be linear up to 1000Gy with a slight saturation towards the end dose. Photoluminescence excitation and emission spectra of the sample were also studied. Fading and reusability studies of the nanophosphor further confirmed the phosphor's suitability for radiation dosimetry.

Thermoluminescence and photoluminescence in the NaCaPO4:Dy3+ phosphor

Dy(3+)-doped NaCaPO(4) phosphor was synthesised at an initiating combustion temperature of 600°C, using urea as the fuel. The crystallinity of the phosphor was investigated by using X-ray diffraction. The photoluminescence and thermoluminescence (TL) behaviours of NaCaPO(4):Dy(3+) phosphor was also studied. It has a simple TL glow curve structure, which does not change when exposed to gamma-rays. A TL glow peak is observed at 230°C and TL intensity is around 1.15 times more compared with commercial CaSO(4):Dy TLD phosphor. The TL characteristics of the phosphor prepared show that it has good sensitivity, linear response with gamma-rays exposure, emission in the blue-yellow regions of the spectrum, negligible fading and excellent reusability. These results make Dy(3+)-doped NaCaPO(4) phosphor attractive for TLD applications.

Changes in thermoluminescence properties of minerals separated from irradiated potatoes and garlic during long-term storage under different light conditions

The effect of different light conditions on the specificity and reliability of thermoluminescence (TL) analysis to detect irradiated samples (potatoes and garlic) during 2 years of storage was investigated. The silicate minerals separated from the nonirradiated samples provided a low-intensity TL glow curve with a maximum peak after 300 °C demonstrating the absence of an irradiation history. The TL glow curve from the irradiated samples provided easy discrimination with TL glow curves of high intensity and maximum peak in temperatures range of 160–185 °C. The results were also confirmed by calculating the TL ratio (TL1/TL2) through normalization (re-irradiation) step. The key parameters of the TL analysis including the TL intensity, TL glow curve shape, and the TL ratio exhibited a time-dependent change. The bleaching effect of different light conditions was also significant, which was most prominent in the case of natural light with a prominent decrease in the TL intensity and ratio. The maximum TL glow peak also showed a shift towards the higher temperature. However, all irradiated samples, irrespective of the storage conditions and time, were easily discernable from the nonirradiated ones considering the shape and intensity of the TL glow curve.

Thermoluminescence, photoluminescence and EPR studies on Mn2+ activated yttrium aluminate (YAlO3) perovskite

Thermoluminescence (TL) measurements were carried out on undoped and Mn2+ doped (0.1mol%) yttrium aluminate (YAlO3) nanopowders using gamma irradiation in the dose range 1–5kGy. These phosphors have been prepared at furnace temperatures as low as 400°C by using the combustion route. Powder X-ray diffraction confirms the orthorhombic phase. SEM micrographs show that the powders are spherical in shape, porous with fused state and the size of the particles appeared to be in the range 50–150nm. Electron Paramagnetic Resonance (EPR) studies reveal that Mn ions occupy the yttrium site and the valency of manganese remains as Mn2+. The photoluminescence spectrum shows a typical orange-to-red emission at 595nm and suggests that Mn2+ ions are in strong crystalline environment. It is observed that TL intensity increases with gamma dose in both undoped and Mn doped samples. Four shouldered TL peaks at 126, 240, 288 and 350°C along with relatively resolved glow peak at 180°C were observed in undoped sample. However, the Mn doped samples show a shouldered peak at 115°C along with two well defined peaks at ∼215 and 275°C. It is observed that TL glow peaks were shifted in Mn doped samples. The kinetic parameters namely activation energy (E), order of kinetics (b), frequency factor (s) of undoped, and Mn doped samples were determined at different gamma doses using the Chens glow peak shape method and the results are discussed in detail.

A computer program for the deconvolution of the thermoluminescence glow curves by employing the interactive trap model

Abstract An efficient computer program has been developed to deconvolute thermoluminescence (TL) glow peaks and optically stimulated (OSL) curves by employing a method of the interactive trap model (ITM). The program is designed to be used easily on the MS Windows-based computer with a graphical user interface. This program could be used to analyze the TL glow curves by using the traditional first-order kinetics (1OK), second-order kinetics (2OK), general order kinetics (GOK), mixed order kinetics (MOK) and the general approximation (GA) method as well as ITM. The program was tested with the generated data and the experimental results of deconvoluted TL glow curves of LiF TLD-100 by assigning five interacting traps and one recombination center. A complete version with full functionalities of this program can be downloaded from the web site http://physica.gnu.ac.kr/TLanal .

Synthesis, characterization, thermo- and photoluminescence properties of Bi3+ co-doped Gd2O3:Eu3+ nanophosphors

Gd2O3:Eu3+ (4 mol%) co-doped with Bi3+ (Bi = 0, 1, 3, 5, 7, 9 and 11 mol%) ions were synthesized by a low-temperature solution combustion method. The powders were calcined at 800°C and were characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), Fourier transform infrared and UV–Vis spectroscopy. The PXRD profiles confirm that the calcined products were in monoclinic with little cubic phases. The particle sizes were estimated using Scherrer’s method and Williamson–Hall plots and are found to be in the ranges 40–60 nm and 30–80 nm, respectively. The results are in good agreement with TEM results. The photoluminescence spectra of the synthesized phosphors excited with 230 nm show emission peaks at ∼590, 612 and 625 nm, which are due to the transitions 5D0→7F0, 5D0→7F2 and 5D0→7F3 of Eu3+, respectively. It is observed that a significant quenching of Eu3+ emission was observed under 230 nm excitation when Bi3+ was co-doped. On the other hand, upon 350 nm excitation, the luminescent intensity of Eu3+ ions was enhanced by incorporation of Bi3+ (5 mol%) ions. The introduction of Bi3+ ions broadened the excitation band of Eu3+ of which a new strong band occurred ranging from 320 to 380 nm. This has been attributed to the 6s2→6s6p transition of Bi3+ ions, implying a very efficient energy transfer from Bi3+ ions to Eu3+ ions. The gamma radiation response of Gd2O3:Eu3+ exhibited a dosimetrically useful glow peak at 380°C. Using thermoluminescence glow peaks, the trap parameters have been evaluated and discussed. The observed emission characteristics and energy transfer indicate that Gd2O3:Eu3+, Bi3+ phosphors have promising applications in solid-state lighting.

Luminescence properties of common glasses for application to retrospective dosimetry

Abstract Seventeen domestic and scientific glass specimens were investigated for thermoluminescence (TL) properties suitable for application to retrospective population dosimetry. Usefulness for retrospective dosimetry was initially judged by the presence of well-defined TL glow peaks and the absence of irradiation-independent luminescence. Of particular interest were TL glow peaks having relatively low trap depths, to prevent significant natural dose accumulation. Minimum useful trap lifetimes would be in the order of weeks. Surveys were undertaken to observe the TL and optically stimulated luminescence (OSL) behaviour of each sample. Most samples showed identifiable TL, with Pyrex in particular, and samples from a jar, a lampshade, and opaque blue beads all showing well-defined TL glow peaks with sensitivities that were not significantly affected by prior irradiation and heating of the sample. Kinetic analysis of these samples showed that their TL emission originates from traps with suitable stability for retrospective dosimetry. It is concluded that, while some glass samples show promising results, the inherent variability of an amorphous substance such as glass means that the suitability of each sample must be determined on a case-by-case basis.

Radiation-induced thermoluminescence characteristics of feldspar upon different heat and microwave treatments

Feldspar minerals are well-known markers for thermoluminescence (TL)-based identification of irradiated foodstuff because of their high TL sensitivity and characteristic TL glow curves. Post-irradiation processing, particularly heating, may affect luminescence properties. In the present study, the effect of boiling, roasting, and microwave treatments on TL properties of irradiated (0, 5, and 10kGy) feldspar was investigated. The TL glow peak faded (TL peak maxima shift towards higher temperature) upon boiling or roasting, which was mainly dependent upon treatment temperature and time. This effect was most apparent in the roasted samples. Liquid samples showed more changes in TL characteristics than solid samples upon microwave treatment; however, the effect was less prominent compared to those of roasting and boiling. TL ratios could not confirm the TL results when boiled and roasted samples were treated at ≥100°C, whereas the microwave treatment showed a negligible effect on the TL ratio.

Prevalence of first‐order kinetics in thermoluminescence materials: An explanation based on multiple competition processes

AbstractTypical materials used in thermoluminescence (TL) dosimetry exhibit the following common characteristics: (i) the temperature of glow peak maximum of individual glow peaks remains practically constant over a wide dose range, (ii) there are no systematic changes in the glow curve shapes with the irradiation dose, and (iii) higher order kinetics is rarely seen in dosimetric materials, while first‐order kinetics is a common occurrence in experimental TL work. Theoretical explanation of these experimental characteristics is an open topic of TL research. In the present work these three characteristics are studied by using several models of increasing complexity. The simplest model studied is based on the empirical analytical general order (GO) expressions, followed by two commonly used models, the well‐known one trap one recombination center models (OTOR) and the interactive multiple trap system (IMTS). Previous researchers have studied the behavior of these models using arbitrary values of the kinetic parameters in the models, and by varying these parameters within limited physically reasonable ranges. In this paper, a new method of analyzing the results from such models is presented, in which the average behavior of real dosimetric materials is simulated by allowing simultaneous random variations of the kinetic parameters, within several orders of magnitude. The simulation results lead to the conclusion that the presence of many competitive processes during the heating stage of TL, may be correlated to the remarkable stability of the glow curve shapes exhibited by most materials, and to the prevalence of first‐order kinetics. This correlation is demonstrated further by a series of simulations in which the number of competitor traps is increased systematically, by adding up to 12 competitor traps in the IMTS model. As the number of competitor traps increases, the average behavior of the TL glow curves tends progressively toward first‐order kinetics, and this in turn results in very small average variations in the shape of the TL glow peak. The simulation results in this paper provide a convincing demonstration and explanation of the stability of the shape of TL glow curves in dosimetric materials, and for the prevalence of first‐order kinetics in TL.

Glow-curve de-convolution analysis of TL glow-curve from constant temperature hot gas TLD readers

Abstract The present work attempts the generalization of the computerized glow-curves de-convolution (CGCD) analysis of glow-curve received under an exponential heating function (EHF) used in stable temperature hot gas thermoluminescence (TL) readers. The analysis is based on single TL glow-peak analytical expressions derived for the EHF cases. A special normalization procedure is suggested which allows the deconvolution of very different glow-curves using the same set of the initial parameters during the CGCD analysis. More than two hundreds of glow-curves corresponding to TL measurements for dose response, for quality control, for low TL statistics, for background and finally glow-curves with undesired spurious signals. The results show that the CGCD analysis, which is widely used in the case of linear heating, can be used and be equally effective for the case of EHF as well.

The analysis of thermoluminescent glow peaks of natural calcite after beta irradiation

In this study, the thermoluminescence properties of natural calcite samples were examined in detail. The glow curve of the sample irradiated with beta radiation shows two main peaks, P1 (at 115 °C) and P4 (at 254 °C). The additive dose, variable heating rate, computer glow curve deconvolution, peak shape and three point methods have been used to evaluate the trapping parameters, namely the order of kinetics (b), activation energy (E) and the frequency factor (s) associated with the dosimetric thermoluminescent glow peaks (P1 and P4) of natural calcite after different dose levels with beta irradiation.

The 110<sup>0</sup> C Thermoluminescence Peak as a Probe in Bioactivity Study of the 58S Sol-Gel Bioactive Glass

Results of the present study provide strong indications towards the effective application of the 110oC Thermoluminescence (TL) peak in discriminating between different bioactive responses for the case of the 58S bioactive glass. The in vitro bioactivity of this glass in the form of powder in SBF solution was tested for various immersion times, ranging between 0 and 6 days. This TL peak is ubiquitously present in all 58S samples, for all immersion times. The intensity of the110oC TL peak was proven to be very sensitive to the different bioactive responses, indicating a strongly decreasing pattern with increasing immersion time in SBF, easily identifying thus the loss of silica. This loss is reflected to the decrease of the 110oC TL peak intensity, which appears to be fast even for the shorter immersion times. The 110oC TL glow peak intensity and sensitization could also be yielding a time scale regarding the beginning of some among the several stages included in the bioactivity sequence.