Thermoluminescence Data Research Articles

Isothermal Decay Analysis of Thermoluminescence Peaks of Nano-α-Alumina

This study investigates the thermoluminescence (TL) behavior of nano α-Al2O3 (40 nm) within the temperature range of 110 to 160°C to elucidate the kinetic mechanisms governing its TL response. The isothermal decay curves were analyzed to determine the order of kinetics and activation energies of the TL peaks. The ln(I) vs. time plot revealed a nonlinearity starting at 140°C, indicating that the TL peaks do not follow first-order kinetics in this temperature region. Subsequent analysis confirmed that the TL data align with second-order kinetics, with a kinetic-order parameter of b = 2.0 providing the best linear fit. Further examination of the ln(slope) vs. 1/kT relationship revealed a composite structure in the TL response, characterized by three distinct linear sections. These sections correspond to activation energies of 0.6±0.12 eV, 1.07±0.25 eV, and 1.61±0.47 eV, respectively, suggesting the presence of three different centers contributing to the dosimetric peak. The findings underscore the complex nature of the TL response in nano α-Al2O3, highlighting the necessity of considering multiple kinetic components in the analysis of its TL properties. This study enhances our understanding of the thermoluminescent behavior of nano α-Al2O3 and provides a basis for further research into its applications in dosimetry

A custom-made integrated system for thermoluminescence and radioluminescence spectroscopy

Thermoluminescence (TL) and Radioluminescence (RL) are widely used in dosimetry applications. We present a custom-built integrated system, designated LUMI22, for measuring TL, TL spectroscopy, RL, and RL as a function of temperature. LUMI22 includes a heating system based on Kanthal® A1 alloy (FeCrAl), a microcontroller to regulate the temperature ramps (e.g. 1–5 °C/s). To irradiate samples an X-ray tube (Moxtek 50 kV, 50 μA) is powered, controlled, and monitored by an FTC-200 standard controller. The dose rate at the sample position is 0.43 Gy/min. Light collection includes a Photomultiplier Tube (PMT, Hamamatsu H10493-012:HA, 185–850 nm). Additionally, a miniature fiber optic spectrometer (Ocean Optics, QE65000, range 200–1100 nm) coupled with a 1000 μm diameter fiber optic (QP1000- 2-UV-VIS) was employed for TL and RL spectroscopy measurements. To assess the functionality of the system, it was used to measure TL and RL from Al2O3:C,Mg, Al2O3:C and TLD-100 phosphors which have been previously well investigated. The measured TL and RL data were well compared to the published ones, confirming the functionality of the system.

Comparing thermoluminescence data on lanthanides in 36 compounds with predictions from vacuum referred binding energy diagrams

Thermoluminescence (TL) often involves the liberation of a charge carrier (an electron or a hole) from a charge carrier trapping centre into the conduction band (CB) or the valence band (VB) with subsequent recombination with a counter charge carrier at a luminescence centre. TL glow peak analysis can provide the energy ΔEt needed to liberate such charge carrier which then defines the location of the charge transition levels (CTL) of the carrier trapping centres below the CB-bottom or above the VB-top. The temperature at the maximum of the TL glow peak changes 3–4 K per 0.01 eV change in ΔEt thus providing an extremely sensitive probe of energy changes in CTLs. This work collects and reviews data on glow peaks due to electron or hole release from lanthanide dopants in 36 different inorganic compounds. To compare results from different literature sources, data were always re-analysed using the same method that is solely based on the temperature at the maximum of the glow peak. The changes in ΔEt along the lanthanides series provides insight at the sub 0.1 eV level on the changes in CTL energies. We will use a compound-dependent parameter to account for the nephelauxetic effect and a compound dependent parameter to account for lattice relaxation around the lanthanide. Together with information from lanthanide luminescence spectroscopy, the vacuum referred binding energy (VRBE) diagram will be constructed for each compound. The lanthanide electron or hole trap depth read from the VRBE scheme will be compared with that derived from the TL glow peak. Surprisingly good agreement will be demonstrated.

The Apollo 17 Regolith: Induced Thermoluminescence Evidence for Formation by a Single Event ∼100 Million Years Ago and Possibly the Presence of Tycho Material

AbstractWe explored the geological history of the Taurus‐Littrow Valley at the Apollo 17 landing site through the induced thermoluminescence (TL) properties of regolith samples collected from the foothills of the Northern and Southern Massifs, from near the landing site, and from the deep drill core taken in proximity to the landing site. The samples were recently made available by NASA through the Apollo Next Generation Sample Analysis program in anticipation of the forthcoming Artemis missions. We found that the two samples from the foothills of the massifs exhibit induced TL values approximately four times higher than those of the valley samples. This observation is consistent with their elevated plagioclase content, indicating their predominantly highland material composition. Conversely, the valley samples display induced TL values characteristic of lunar mare material. The samples from the deep drill core demonstrate uniformly induced TL properties, despite originating from depths of up to 3 m. Notably, one of the samples from the lower section of the deep drill core presents anomalous‐induced TL readings. This anomaly coincides with elevated levels of low‐potassium KREEP along with reduced quantities of anorthositic gabbro and orange glass, and could be due to the traces of phosphate minerals. Alternatively, this observation raises the possibility that this sample contains Tycho impact material. The induced TL data is consistent with the regolith, extending to a depth of at least 3 m, having been deposited by a singular event approximately 100 million years ago. This timing aligns with the hypothesized formation of the Tycho crater.

Chasing snails: Automating the processing of EMCCD images of luminescence from opercula

Opercula of the gastropod Bithynia tentaculata are composed of calcite, and are typically 2–4 mm in length. They emit a thermoluminescence (TL) signal that can be used for dose reconstruction, and spatially resolved TL data from them can be obtained using an electron multiplying charge coupled device (EMCCD). However, when multiple measurements are made of the same sample with imaging detectors such as the EMCCD, registering the different images is crucial so that when regions of interest (ROI) are defined they consistently relate to the same part of the specimen. Previous work on opercula has undertaken this registration by hand, but this is prohibitively time consuming and is also potentially prone to human error. An automated registration process is described, and its use is illustrated using a dose recovery experiment. Without registration more than half of the regions of interest defined across the operculum failed the recycling test, and for those ROIs which did pass recycling the dose recovery ratio varied from 0.7 to 1.2. After registration more than 97% of ROIs passed recycling and all these ROIs gave dose recovery ratios within two sigma of unity. The automated registration process described here has potential for application to other types of solid sample such as rock slices provided they are not perfectly circular.

Effect of temperature on lanthanide charge transition levels and vacuum referred binding energies

Location of lanthanide levels in the bandgap, vacuum referred binding energy (VRBE) in the lanthanide ground state and energy of lanthanide charge transition levels (CTLs) are just three different namings for the same concept. A concept of importance for the performance of lanthanide activated compounds. Energy differences of CTLs with the conduction band bottom and valence band top are important when it concerns e.g. lanthanide luminescence, charge carrier trapping, and valence stability. Effect of temperature on CTL energy or VRBE has so far never been addressed despite that luminescence application and thermoluminescence studies may span a temperature range from 10 K to 1000 K. In this work information on the bandgap (or energy of host exciton creation) around 10 K and at RT in compounds is gathered to demonstrate that bandgap decreases by 0.1 eV to 0.3 eV when temperature increases to RT. A similar decrease will be demonstrated for the energy of electron transfer from the VB to a trivalent lanthanide. The findings have consequences for VRBE-diagram construction, i.e. the experimental parameters for such construction should all apply to the same temperature. They also have consequences on how to relate luminescence thermal quenching energy barriers and TL derived electron and hole trap depths with a VRBE diagram. By proper evaluating the effects of temperature, accuracy of VRBE diagrams and consistency with luminescence and thermoluminescence data can be improved.

Role of Gd3+ ions in alumino borosilicate glasses studied through structural, optical and thermoluminescence characteristics for gamma dosimetry applications

This paper reports the structural, optical and thermoluminescence properties of Gd3+ ions incorporated alumino-borosilicate glasses, prepared through the melt-quench technique. The amorphous nature of the glasses is confirmed through XRD study. Network vibrations of borate and silicate groups, vibrations of hydrogen bonding and hydroxyl groups are realized via FTIR study. The Gd3+ transition peaks are absent in the near ultraviolet, visible and NIR regions, and the indirect bandgap values were determined through UV–Visible–NIR study. Photoluminescence measurements showed a concentration quenching in the glasses beyond 1.5 mol % of Gd3+ ions. Based on the thermoluminescence (TL) data, the 2 mol % of Gd2O3 doped glass (BSGD5) was chosen as optimum sample because of the presence of maximum TL intensity. The BSGD5 glass displayed TL response linearity in 0.25–1 kGy dose region giving a high signal sensitivity of 220,068 counts. g−1 kGy−1 in this region. With nearer tissue equivalence and a minimum detectable dose of 0.02 Gy, the suitability of BSGD5 glass for gamma dosimetry application was deducted. Electron spin resonance (ESR) study validated the presence of intrinsic defects in Gd3+ glasses which are responsible for changes in the intensity and shape of TL glow curves. Hence, from the obtained results Gd3+ doped alumino borosilicate glasses can be considered as potential candidates for gamma dosimetry application.

Radioluminescence Processes in Cerium-Doped Silica Glasses

Rare-earth-doped silica glasses are promising materials for ionizing radiation dosimetry. In this paper, a bulk glassy silica doped with Ce ions, was prepared via the sol-gel technique and drawn at about 2000 °C into a cylindrical capillary rod. Under X-rays, this sample presents a radioluminescence (RL) signal that can be exploited for dose rate real-time monitoring with remarkable linear response spanning 6 decimal orders of magnitude. In order to elucidate RL signal dynamics associated with free carriers trapping-detrapping and recombination during and after X-ray irradiation, we studied the obtained RL signals using a kinetic model involving one or several trapping states and one recombination center. With this model and using appropriate sets of trapping parameters, extracted from the thermoluminescence data, the RL signal was numerically simulated, along with the populations of the relevant traps and centers. Several experimentally observed characteristics of the RL signals were explained using the model.

Estimation of activation energy using skewness of TL data as symmetry parameter in peak shape method

The retrapping and recombination mechanism of charge carriers in a thermoluminescence (TL) process governs the shape of a glow curve. In peak shape method the shape of a glow curve is exploited through various symmetry parameters to estimate activation energy. In statistical sense, skewness is a measure of distribution asymmetry of a dataset and hence may be useful to reflect the shape of a TL curve through its asymmetry. In this work, we investigate the applicability of skewness as a symmetry parameter and propose a new set of peak shape relations in terms of skewness of the data to extract activation energy from an isolated TL peak. The applicability of present method is verified by employing it to the TL peaks simulated in General Order Kinetics (GOK) and One Trap One Recombination centre (OTOR) equations. The present method yields consistent results for all the glow curves except for highly saturated cases with heavy retrapping. This limitation is investigated by studying the dependence of skewness on the ratio of retrapping to recombination probabilities. Finally, the present peak shape formulae are tried on experimental TL curves reported in literature and the results are quite satisfactory. The present peak shape coefficients are listed explicitly so that they can be used to estimate activation energy using skewness of isolated peaks deconvoluted from experimental TL data.

Green synthesis, structural and luminescent characterization of BaZrO3:Eu3+ nanoparticles

This paper presents experimental results of the structural, morphological, and luminescence characterization of Eu 3+ doped BaZrO 3 powders produced by the green synthesis method. The highly crystalized cubic structure perovskite powders of the formula BaZrO 3 were synthesized by the chemical hydrothermal method. The phase of the compound and the average particle size were determined using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Powder samples were characterized also by photoluminescence (PL) and thermoluminescence (TL) techniques. Results showed that BaZrO 3 crystallizes in its perovskite cubic phase, with a crystal size circa 40 nm. The presence of each element of the compound was confirmed by the energy disperse spectroscopy (EDS) technique. The PL emission spectra, at room temperature, were obtained using 395 nm as excitation wavelength. The spectra showed the characteristic emissions of Eu 3+ ion. The intensity of the PL emission spectra varies with the Eu 3+ concentration and shows a maximum luminescence efficiency when the synthesis of BaZrO 3 was performed using a content of 5 mol% Eu³⁺. The thermoluminescence data shows that at the heating rate of 10 °C/s, BaZrO 3 :Eu 3+ doped with 5% of dopant concentration exhibits two TL peaks: first of them rapidly decaying peaks at about 110 °C and a high sensitivity peak at 235 °C TL. The correlation between luminescence intensity and concentration quenching of the prepared phosphor was investigated. Present findings substantiate the ability of the BaZrO 3 nanopowder sample to be a promising candidate for luminescence applications.

Behaviour of Radio- Thermoluminescence (X-Ray Irradiated), Thermal and Structural Characterization of Limestone

In this study, it was reported radioluminescence properties of limestone from Kütahya, Turkey for the first time in this study, which has been the subject of many studies in both mineralogical and gemological fields. Limestone is the general name of carbonate roks, which is the mineral with typical colors according to the impurity elements in rock and exhibited luminescence properties under x-ray irradiation. The radio&thermoluminescence data were analyzed for limestone. Besides, x-ray diffraction pattern was created for structural characterization, scanning electron microscope images and energy dispersive x-ray spectroscopy maps were taken to determine morphological features. When the radioluminescence spectrum of the limestone was detailed, a broad emission consisting of several peaks was observed in the visible region. In the thermoluminescence spectrum taken after the x-ray excitation of the limestone, three thermoluminescence peaks were observed at 97 oC, 170oC and 320 oC. Also; TL kinetic parameters are reported; The activation energy (E) and frequency factor (s) of the first peak were determined in detail using the methods of peak shape and varying heating rates.

Dosimetric and TL investigation of natural and heat-treated Pakistani Onyx at high beta doses

Extensive Thermoluminescence (TL) glow curve analysis of natural (S1) and heat-treated (S4) Pakistani Onyx marble is reported exploring an alternative natural radiation dosimeter. TL curves for β-doses ranging from 0.5 Gy to 10 kGy are measured within the temperature range of 25–500 °C and analyzed to generate dose response curves (DRCs). Single saturation exponential function and DRCs are used to evaluate the characteristic dose value and the intensity saturation level. The glow peak repeatability test identifies unstable TL trapping sites in S1 at high temperatures (≥350 °C). Fading analysis of S4 shows that a major signal loss (40%) occurs within 24 h because of low temperature (<130 °C) peaks. After irradiation, time-temperature investigations are performed to optimize the pre-heat condition and remove fast fading peaks. The kinetic parameters are estimated using the TM-Tstop technique and the curve deconvolution method. The post-irradiation preheat at 100 °C for 10 s and TL data collection up to 400 °C with a heating rate of 5 °C/s is concluded as appropriate measurement condition to perform dosimetric studies of S4. The quantitative analysis of S4 dose response showed a linear behavior from 2 to 20 Gy, supra-linear from 20 to 5000 Gy, and sublinear response after 5–10 kGy. The minimum detectable dose (MDD) and percentage coefficient of variation (COV) of repeatability for S4 are 236 ± 8 mGy and 1.53% respectively. The study concludes that Pakistani Onyx marble, with thermal treatment of 500 °C for 1 h, can be a radiation dosimeter for high dose applications.

Enhancing the optical information storage performance of Ca3Ga4O9: Bi3+ by co-doping with Zn2+ ions

The generation of optical storage based on phosphor materials is a significant new technology for data storage. A key material is Ca3Ga4O9: Bi3+ which has the potential for real-time reading of optical information. This paper describes data from a series of Ca3Ga4O9: Bi3+, Zn2+ phosphors synthesized via a high temperature solid-state reaction. Zn2+ ions had been co-doped as charge compensators to improve the performance of optical information storage. The influence of Zn2+ ions on both structure and luminescence properties are reported. It is clear that co-doping of Zn2+ ions can enhance the emission of Ca3Ga4O9: Bi3+ phosphors via charge compensation and lattice distortions. Photoluminescence peaks of the sample at 528 nm, 500 nm and 484 nm correspond to the transition of Bi3+ due to changes in occupancy of different Ca2+ positions. Thermoluminescence data suggest that Zn2+ ions associate with the defects inside the Ca3Ga4O9: Bi3+ which reduce cation vacancies so as to reduce the number of shallow traps, and increase the concentration of the valuable deeper traps.

Study of Spectrally Resolved Thermoluminescence in Tsarev and Chelyabinsk Chondrites with a Versatile High-Sensitive Setup.

Thermoluminescence (TL) research provides a powerful tool for characterizing radiation-induced processes in extraterrestrial matter. One of the challenges in studying the spectral features of the natural TL of stony meteorites is its weak intensity. The present work showcases the capabilities of a high-sensitive original module for measuring the spectrally resolved TL characteristics of the Chelyabinsk and Tsarev chondrites. We have analyzed the emission spectra and glow curves of natural and induced TL over the 300–650 nm and RT–873 K ranges. A quasi-continuous distribution of traps active within the 350–650 K range was found in the silicate substructure of both meteorites under study. Based on the general order kinetic formalism and using the natural TL data, we also estimated the activation energies of EA = 0.86 and 1.08 eV for the Chelyabinsk and Tsarev chondrites, respectively.

Influence of co-doping germanium ions on the long persistent near-infrared luminescence of ZnAl2O4:Cr3+

A series of infrared long persistent phosphor samples of ZnAl2O4: Cr3+ with various doping concentrations of Ge4+ ions were synthesized via a high temperature solid state reaction method. Powder X-ray diffraction, persistent spectra, afterglow decay curves, photoluminescence and isometric thermoluminescence spectra were collected to identify the influence of the Ge4+ ions on the luminescence in the spinel structure. The results define an optimal co-doping of germanium ions (2 mol%) in the ZnAl2O4: Cr3+ can enhance the afterglow time of the phosphor. With the increase of co-doping, the diffraction peaks shift to the shorter angles which confirm a swelling of the crystal cell. Thermoluminescence data emphasise there are modifications from the presence of the Ge ions. The phenomenon that the long-wave emission reaches the maximum value of the spectral spread before the short-wave signal provides interesting insights into the charge transfer process.

THREE-POINT AREA METHOD FOR THERMOLUMINESCENCE GLOW CURVE ANALYSIS AND ITS APPLICATION TO THE GLOW PEAK OF K2SRP2O7:PR.

A method has been proposed to evaluate the kinetic parameters, viz. activation energy ($E$) and order of kinetics ($b$) from a single or isolated thermoluminescence (TL) glow peak. Along with the area under the entire curve, this method uses a set of three arbitrary data points and calculates the partial area under the curve from each point to the endpoint. In this way, the entire information associated with the curve is used and the method is named as 'Three-Point Area' (TPA) method. We have applied it successfully on a number of theoretically simulated TL curves generated in One Trap One Recombination centre (OTOR) model and General-Order Kinetics (GOK) model under quasi-equilibrium approximations with linear heating scheme. The activation energies are found in good agreement with input values for both the models. For OTOR model, temperature average of order of kinetics is estimated to compare with the present result. Systematic analysis is carried out for estimation of errors inherent in the method in the purview of GOK model. A closer look on the results reveals that any set of three points, preferably chosen from the rising side of the curve, can yield activation energy and order of kinetics. The validity of the method to extract $E$ and $b$ from experimental glow curves is exemplified by considering experimental TL data reported in literature. Finally, a complete study starting from the synthesis of a new phosphor $\mathrm{K_2SrP_2O_7:Pr} $ and analysis of the recorded TL data to estimate $E$ and $b$ employing the TPA method has been reported.

Blue and near infrared luminescence degradation by electron beam irradiation in Y2O3:Tm3+ nanophosphors

Cathodoluminescence (CL) degradation measurements on Y2O3:Tm3+ nanoparticles were made to test for potential application as a blue phosphor in low-voltage field emission displays. The incorporation of Tm3+ into the Y3+ sites in the Y2O3 lattice was confirmed by x-ray photoelectron spectroscopy and CL spectra. The Y2O3:Tm3+ nanophosphor was investigated under vacuum and oxygen (O2) backfilled conditions in order to control surface chemical adsorption. The Auger electron spectroscopy (AES) and the CL data collection were performed simultaneously when the nanophosphor was bombarded with a beam of electrons with a 3 μA beam current and an accelerated voltage of 2 keV in both atmospheres. The Y2O3:Tm3+ nanophosphor displayed strong blue (457 nm) and relatively weak near infrared (812 nm) emissions. The CL intensity decreased as a function of electron dose in vacuum, while in the O2 backfilled pressure it only started to decrease after an electron dose of ∼250 C/cm2 after removal of C from the surface. The CL emission’s intensity increased at an initial electron dose in the O2 backfilled pressure due to the desorption of C from the surface. The removal of C and other surface impurities from the surface was ascribed to be due to electron stimulated surface chemical reactions. The AES and the thermoluminescence (TL) data suggested that an O deficient layer was formed on the surface. TL glow curves confirmed that the electron beam induced deep traps at activation energies of 1.28, 1.37, and 1.42 eV in the Y2O3:Tm3+ nanophosphor that was attributed to oxygen vacancies. Mechanisms, where O deficiency leads to an improvement in the CL intensity, were also discussed.

Extraction of some trapping parameters from experimental thermoluminescence (TL) signal of alumina (α-Al2O3) using analytical models

The exploitation of thermoluminescence (TL) signals constitutes the background of important and phenomenological methods used for estimating the kinetic parameters such as the activation energy (E), the frequency factor (s) and the general order of kinetics (b). These parameters are, in general, poorly known and all the used methods often diverge on their determined values. In the present paper, we investigate the suitability of the general phenomenological equations used to extract some trapping parameters from experimental TL signals of alumina (α-Al2O3). α-Al2O3 TL signal exhibits, under hard uv-irradiation (4.8 eV), two TL-main peaks located at 415 nm and 696 nm corresponding to F and Cr3+ centers respectively. To this aim, we numerically computed the analytical expression of TL which results from general order kinetic (b) taking into account the trapped charge concentration and the radiative/retrapping yield R. The computed curves for R = 1 fit perfectly the experimental data, allowing the extraction of some TL data as E, b and s from TL bands of alumina.

Effect of Ce3+ concentration on persistent luminescence of YAGG:Ce3+,Cr3+,Nd3+ nanophosphors obtained by the co-precipitation method

Synthesis of Y3Al2Ga3O12 garnet (YAGG) nanophosphors co-doped with Ce3+, Cr3+, and Nd3+ ions by co-precipitation is reported. The effect of Ce3+ concentration on the structure of garnet and on optical properties including persistent luminescence was investigated. The X-ray diffraction measurements showed that single garnet phase was obtained. The contraction of the crystallites size was observed with increasing the cerium concentration. The combined emission of three used co-dopants together allows to extend persistent luminescence spectral range. The photoluminescence, excitation and persistent luminescence spectra were collected and the optimal Ce3+ concentration for the highest efficiency conversion of UV and blue light into the red and the near infrared emission was determined. Based on thermoluminescence data, the effect of Ce3+ concentration on the traps redistribution was also investigated.

Comparisons of thermoluminescence signals between crystal and powder samples

Thermoluminescence data for several materials show that there are measurable differences between signals from crystalline and powder variants. With examples starting with crystalline calcite, Iceland Spar, and aragonite, and calcium fluoride (with rare earth impurities) the crushed material has altered signals. The changes are variously (i) alterations in the relative intensities of the glow peaks, (ii) modifications of the emission spectra, (iii) higher intensity per unit weight from the powdered material and (iv) examples with different numbers of peaks. (v) Whilst the thermoluminescence peaks sometimes appear at lower temperatures, which is consistent with features (i) to (iv), caution is required as there can be experimental reasons which also result in lowered temperatures. These include altered thermal coupling and/or temperature gradients at the sample heater. The scale of potential experimental variations is surprisingly large, and they have relevance to all thermoluminescence studies. Examples of such effects have been noted and new suggestions to minimise them are presented.