Thermoluminescence Research Articles

Li9Mg3[PO4]4F3 fluorophosphate as a new thermoluminescent material: Experimental and theoretical study

In this work, radioluminescence (RL), thermoluminescence (TL) and photoluminescence (PL) of fluorophosphate Li9Mg3[PO4]4F3 as a possible dosimetry material are studied for the first time. It was found that the irradiated sample exhibits significant thermoluminescence in the temperature range of 100–300°С with the main peak at 205°С. The RL, PL and TL spectra consist of one broad band centered at 400 nm which was attributed to defects in the structure of Li9Mg3[PO4]4F3. The energy required to excite defects in Li9Mg3[PO4]4F3 determined by UV–vis spectroscopy is 4.4 eV (λ ≈ 280 nm). Additional evidence for intrinsic defects was obtained from the electron paramagnetic resonance (EPR) in Li9Mg3[PO4]4F3. The DFT method was employed to simulate various defects including single and complex, neutral and charged vacancies. The formation energies of vacancies were predicted and their effect on the electronic structure and optical properties was established. These intrinsic defects introduce additional electronic states into the band gap and absorption bands in the visible region, the position and intensity of which strongly depend on the type of defect. Our experimental and theoretical studies reveal that Li9Mg3[PO4]4F3 can be a promising optical matrix suitable for dosimetric applications. As evidence, the main functional characteristics of the new material are given.

Time-resolved photoluminescence analysis of ceramic Ce:GAGG scintillators.

This paper introduces the characteristics and efficiency of post-treatment methods for enhancing the timing resolution of ceramic Ce:GAGG scintillators. The thermal annealing and surface treatments were included to analyze their impact on time-resolved photoluminescence (TRPL) and thermoluminescence (TL) characteristics. Optical properties were improved by suppressing nonradiative recombination due to the reduced surface defects, while heat-treatment removes traps as confirmed by TL measurements. TRPL decay characteristics revealed that samples treated with mechanical polishing followed by heat treatment exhibited the best scintillation performance, with a slow component of 272.3 ns. These findings will aid in developing techniques for improving the luminescence of other inorganic scintillators.

Thermoluminescence properties of nano-alumina with two different particle sizes

This research aims to examine the thermoluminescence (TL) properties of nano-sized alumina, including the relationship between TL intensity and absorbed dose, the identification of individual luminescence peaks, and determining trap parameters for use as a possible dosimeter. The samples were exposed to 530 to 2646 Gy doses from 60Co irradiation. The results show that micro-sized α-Al2O3 had a main dosimetry peak at Tm = 435 K, while nano-α-Al2O3 samples with particle sizes of 40 and 50 nm displayed a TL luminescence glow curve, with the primary dosimetry peak located in the low-temperature range and a complex structure at higher temperatures (above 500 K). The primary dosimetry peak was influenced by nanoparticle size, with a maximum of 460 K for the 40 nm sample and 467 K for the 50 nm sample. The main dosimetry peak was described by the superposition of two peaks

Oxygen vacancy induced luminescence in Y2Zr2O7 and its removal on Eu3+ doping leading to enhanced quantum efficiency

To circumvent the low color rendering index and high color temperature of existing white light emitting diodes (LEDs), a lot of attention has been given on designing efficient red emitting luminophores for phosphor converted LEDs (pcLEDs). Utilizing the favorable properties of Y2Zr2O7 (YZO) pyrochlore and Eu3+ as dopant ion we could produce bluish white light emitting YZO and red light emitting YZO:Eu3+ (YZOE). Based on monoexponential luminescent decay, we could infer europium ion occupies Y3+ site which is in line with density functional theory (DFT) calculated defect formation energy and positron annihilation lifetime spectroscopy (PALS). YZO on UV irradiation generates bluish white light endowed by both neutral and singly ionized oxygen vacancies but with very meager photoluminescence quantum yield (PLQY∼1.2%). On doping Eu3+ ion in YZO; oxygen vacancy is completely removed with efficient host to dopant energy transfer leading to bright red emission with PLQY∼ 8.2%. The feasibility of YZO to Eu energy transfer is well established using DFT calculations. Reduction in density of oxygen vacancies on doping is well corroborated using electron paramagnetic resonance (EPR) and thermoluminescence (TL) spectroscopy and very well supported by DFT calculations. In this work by harnessing the potential of pyrochlore lattice defects and doping engineering we could enable almost 8-fold increase in PLQY in YZOE.

Gonads Exposure to Scattered Radiation and Associated Second Cancer Risk from Pelvic Radiotherapy

Purpose: The purpose of this study was to evaluate the risk of gonad cancer induction in adults with pelvic cancer (bladder, rectum, endometriosis) after radiation therapy.
 Materials and Methods: In two fractions of radiotherapy, Thermo Luminescence Dosimeters (TLDs) measured the peripheral dose to the testis and ovary. With 3D planning, all patients received a 45 Gy total dose in four fields in the prone position. Researchers investigated the doses produced by linear accelerators operating at 18 MeV.
 Results: The mean Excess Relative Risk (ERR) was measured based on the BEIR IIV models. Right pelvic radiotherapy of men was 0.795 ± 0.168 and 0.675 ± 0.134, and for women was 1.015 ± 0.561 and 0.884 ± 0.468 after 5 and 10 years of treatment, respectively. Left pelvic radiotherapy was 0.855 ± 0.172, 0.725 ± 0.138 for men and 0.880 ± 0.464, 0.722 ± 0.342 for women respectively (95% confidence interval). These values for women were higher (p < 0.05).
 Conclusion: Estimating the second cancer risk of untargeted organs is crucial in radiotherapy. The out-of-field doses can be minimized by using a linear accelerator with a single energy mode and proper shields.

Synthesis, characterization and thermoluminescence properties of LiCaPO4 phosphor for ionizing radiation dosimetry

Many minerals and compounds show thermoluminescence (TL) properties but only a few of them can meet the requirements of an ideal dosimeter. Several phosphate materials have been studied for low-dose dosimetryin recent times. Among the various phosphates, ABPO4-type material shows interesting TL properties. In this study, an ABPO4-type (A = Lithium, B=Calcium) phosphor is synthesized using a modified solid-state diffusion method. Temperature is maintained below 800 °C in every step of phosphor preparation to obtain the pure phase of Lithium calcium phosphate (LiCaPO4). The purpose of this work is to synthesize LiCaPO4 using a simple method, examine its structural and luminescence properties in order to gain a deeper understanding of its TL characteristics. The general TL properties, such as TL glow curve, dose linearity, sensitivity, and fading, are investigated. Additionally, this study aims to determine various kinetic parameters through Glow Curve Deconvolution (GCD) method using the Origin Lab software together with the Chen model. XRD analysis confirmed the phase purity of the phosphor with a rhombohedral structure. Lattice parameters, unit cell volume, grain size, dislocated density, and microstrain were also calculated from XRD data. Raman analysis and Fourier Transform Infrared analysis were used to collect information about molecular bonds, vibrations, identity, and structure of the phosphor. To investigate TL properties and associated kinetic parameters, the phosphor was irradiated with 6.0 MV (photon energy) and 6.0 MeV (electron energy) from a linear accelerator for doses ranging from 0.5 Gy to 6.0 Gy. For both photon and electron energy, TL glow curves have two identical peaks near 200 °C and 240 °C.The TL glow curves for 0.5 Gy–6 Gy are deconvoluted, then fitted with the appropriate model and then calculated the kinetic parameters. Kinetic parameters such as geometric factor (μg), order of kinetics, activation energy (E), and frequency factor (s) are obtained from Chen's peak shape method. The dose against the TL intensity curve shows that the response is almost linear in the investigated dose range. For photon and electron energy, the phosphor is found to be the most sensitive at 2.0 Gy and 4.0 Gy, respectively. The phosphor shows a low fading and after 28 days of exposure, it shows a signal loss of better than 3%. The studied TL properties suggest the suitability of LiCaPO4 in radiation dosimetry and associated fields.

Photoluminescence and thermoluminescence properties of pure and rare-earth-doped ZrO2 prepared by Pechini-type sol-gel.

In this article, photoluminescence (PL) and thermoluminescence (TL) properties of ZrO2 , ZrO2 :Dy3+ , ZrO2 :Dy3+ -Gd3+ , ZrO2 :Dy3+ -Yb3+ , ZrO2 :Dy3+ -Er3+ , and ZrO2 :Dy3+ -Sm3+ phosphors synthesized by the Pechini method were investigated. The crystal structure, thermal properties, morphology, PL and TL properties were investigated using X-ray powder diffraction (XRD), differential thermal analysis/thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), PL and TL, respectively. The room temperature emission bands corresponding to 4 F9/2 →6 HJ (J= 9/2, 11/2, 13/2 and 15/2) transitions of Dy3+ ions were measured. The phosphors were analysed using Tm -TSTOP , variable dose, and computerized glow curve fitting methods. Reusability, dose-response, and fading characteristics were investigated. The phosphors have a natural TL emission that vanished by heating treatment. Moreover, new peaks with similar properties to the natural emissions were observed after high-dose irradiation and long-term fading experiments. The glow curves of the phosphors have 13 individual peaks and many low- and high-temperature satellite peaks. The origin of the peaks is ZrO2 host material and doping with rare-earth ions (Gd3+ , Dy3+ , Yb3+ , Er3+ and Sm3+ ) does not lead to a new glow peak. The dopants cause drastic changes in individual peak intensities of ZrO2 .The initial fading rates of all the phosphors are relatively fast, but they slow down as time goes on.

Assessment of structural and thermoluminescence characteristics of porcelain used as an electrical insulator

AbstractIn the present work, the thermoluminescence (TL) properties and kinetics of beta‐irradiated porcelain used as an electrical insulator are investigated in great depth. Thermal annealing at 1100°C slightly changes the trap system, whereas heating over 500°C increases the visual TL intensity of the peaks. X‐ray diffraction, scanning electron microscopy with energy dispersive X‐ray spectroscopy, atomic absorption spectroscopy, and Fourier transform infrared spectroscopy were used to confirm the structural, morphological, and chemical investigations of the materials. The TL glow curve characteristics, repeatability, storage time properties, and dose–response behavior of non‐annealed and annealed porcelain have all been well investigated. Within the confidence interval, the material has been demonstrated to have excellent reusability. A linear response in the dose range of 0.1–3 Gy was observed. TM–Ts, initial rise, and computerized glow curve deconvolution methodologies were used to complete the kinetic study. The outcomes of the detailed investigations demonstrated that the sample was suitable for TL dosimetry potential uses.

Thermoluminescence study of ϒ irradiated SrSO4 nanoparticles doped with Eu for feasible application in dosimetry

SrSO4 nanoparticles doped with different concentrations of Eu were synthesised by using co-precipitation method and annealed at 500 °C, 700 °C and 900 °C respectively. The prepared SrSO4:Eu nanophosphors shows highly crystalline orthorhombic structure with crystallite size of about 30 nm as observed from the X-ray diffraction (XRD) pattern. TEM (Transmission Electron Microscopy) analysis confirms the particle size to be around 40 nm for the synthesised nanophosphors. Energy Dispersive X-ray (EDX) spectrum showed the presence of only Eu dopant without any other impurity into the SrSO4 sample. The thermoluminescence (TL) glow curve of 1 Gy of gamma ray irradiated SrSO4:Eu measured at heating rates 1 K/s has a well-defined single peak at around 468 K. The TL kinetic parameters for the synthesised nanoparticles evaluated using initial rise method, peak shape method, Booth method and deconvolution method were all in agreement and found to be activation energy (E), order of kinetics (b) and frequency factors (s).

Testing the [formula omitted] procedure using TLDs and OSLDs and a lexsyg smart automated reader for precise dosimetry

This work demonstrates the precision achieved with thermoluminescence (TL) and optically stimulated luminescence (OSL) detectors (TLDs and OSLDs) using a procedure that takes advantage of the capabilities of automated TL/OSL readers (lexsyg smart), for potential applications in medical dosimetry. The procedure makes use of the 90Sr/90Y beta source present in the reader to correct for sample-to-sample sensitivity variations. Typical data obtained using four types of TLDs (LiF:Mg,Ti, LiF:Mg,Cu,P, CaF2:Tm, Al2O3:C single crystal) and two types of OSLDs (BeO and Al2O3:C film) are presented along with the estimated uncertainties achieved. The results demonstrate that the material-specific optimized procedure enables a precision (standard deviation of the data) better than 3% in the 0.2Gy–2Gy dose range with all the materials, except for the TL signal of Al2O3:C single crystal. The highest precision (¡ 1%) is achieved using the OSL from Al2O3:C film over a wide dose range (∼0.2Gy to 10Gy).

Studying the kinetic parameters of BaTi5O11 by using the thermoluminescence technique

The present study discusses the thermoluminescence (TL) characteristics of monoclinic barium titanate (BaTi5O11) which is chemically prepared using the sol–gel technique. The crystallinity is confirmed by X-ray diffraction, and the oxidation state of each element, morphology, and particle size of the prepared powder are chemically probed by different spectroscopic tools including X-ray Photoelectron Spectroscopy and Energy dispersive X-Ray spectroscopy. The sample is irradiated by a beta (β)-source with different applied doses in the range of 1.1––385 Gy. The kinetic parameters which correspond to the charge carrier traps were determined. The analysis methods indicated that the TL glow curve of BaTi5O11 consists of 6 overlapped peaks corresponding to 6 electron traps. The values for the trap depth are found to be in the range 0.94–1.40 eV and the TL glow peaks are located between 380.4 and 560.5 K. The study confirms the potential of BaTi5O11 for β-dosimetry.

TL, OSL, EPR, and defect centers in Tb-doped strontium silicate phosphor synthesized by a solid-state reaction method

Strong thermoluminescence (TL) was observed in Tb-doped strontium silicate phosphor prepared by the solid-state reaction method. Two glow peaks are observed at 100 and 190 °C. TL emission spectra indicate three recombination centers. The number of peaks and the kinetic parameters associated with the TL glow peaks of Tb-doped Sr2SiO4 phosphor after gamma irradiation were analyzed by Tm-Tstop and deconvolution methods. A study of defect centers induced by γ-irradiation and identification of defect centers responsible for the observed TL glow peaks has been carried out using the electron paramagnetic resonance (EPR) technique. The observed spectrum at room temperature is a superposition of at least three defect centers. Center I is characterized by an axially symmetric g-tensor with principal values g|| = 2.019, and g⊥ = 2.0013 and is ascribed to a O2− ion. Center II has a rhombic g-tensor with principal values 2.0072, 2.0024, and 1.995 and is assigned to an F+ center (singly ionized oxygen vacancy) and correlates with the 190 °C TL peak. The third center (center III) has an isotropic g-value of 1.991 and is identified as an F+ center.

Comprehensive Investigation of Neolithic Ceramic Samples: Firing Technology and Age Insights

Thermogravimetric (TG/DTG), thermoluminescence (TL), and X-ray powder diffraction (XRD) techniques were applied to characterize samples collected from the archaeological site of Polutepe in Azerbaijan, dating to the Neolithic period, and gave new information on the firing technology. The thermogravimetric analysis of ceramic shards from Polutepe revealed that the firing temperature of the samples was in the range of 700°C, based on the presence of calcite in the sample. XRD analysis confirmed the presence of quartz, feldspar, and clay minerals in the ceramic samples. According to XTD analysis the mineral composition of the ceramic sample from Polutepe site was as follows: Quartz-33.8 mass%, Feldspar (albite)-21.7 mass%, Muscovite- 33.6 mass%, and Calcite- 10.9 mass%.
 TL glow-curve intensity at 325°C was measured to estimate the historical dose of the sample, which was found to be 22.19±1.36 Gy. The concentration of U, Th, and K were 2.24±0.20 ppm , 8.31±0.80 ppm, 2.39±0.23% respectively. Dose rate and age calculation were conducted using the DRAC, version 1.2 and output results are as follows: Environmental dose rate: 3.46±0.19 mGy/a; Age of the sample: 4.400±530 BC years which are in line with the stratigraphically estimated age of this area and with the radiocarbon age (4270±160 BC) reported in our previous work. The results obtained from this multidisciplinary approach provide insights into the firing technology and age of the ceramic samples.

Structural and luminescence studies of Eu3+ doped K2BaSr(PO4)2 phosphor

Eu3+ doped K2BaSr(PO4)2 phosphor which gave red emission, was successfully synthesized by using the solid-state reaction method. The X-ray powder diffraction technique determined the crystal structure and the photoluminescence (PL), and thermoluminescence (TL) were also measured. The XRD pattern of prepared K2BaSr(PO4)2 is good matched with the COD CIF File number 00-100-7161. The structure of the phosphor is orthorhombic. The crystallite sizes are evaluated from diffraction peaks using the Scherrer formula. In PL emission, two peaks are found at 592 nm and 614 nm at 395 nm excitation wavelength. The as-developed phosphor can be used in the development of WLEDs.

The effects of heat treatment on the OSL signal in sodium chloride crystals

Luminescence studies focusing on sodium chloride crystals have been conducted in various parts of the world, including Brazil, India, Greece, Türkiye, Australia, Spain, and Poland. This material shows great promise in the field of dosimetry, as it has demonstrated high sensitivity, excellent reproducibility, a linear response, and a low minimum detectable dose. Moreover, it holds significant potential for applications in accidental dosimetry, providing valuable results for dating and retrospective dosimetry purposes. Natural sodium chloride encompasses different types of salts, such as Himalayan black salt, pink salt, and sea salt. The presence of these salt variations is attributed to their composition, which includes not only pure sodium chloride but also other elements like magnesium, potassium, sulfur, and calcium. These additional elements contribute to the unique characteristics and properties exhibited by these types of salts. A comprehensive study was conducted to investigate the effects of thermal treatments on pink salt crystals, aiming to enhance their luminescent intensity and thereby improve their sensibility to detect ionizing radiation. By subjecting the crystals to various thermal treatments, we observed significant changes in their luminescent signals. Firstly, we observed a change in the shape of the Thermoluminescence (TL) curve, indicating modifications in the properties of the luminescent F-centers present in the crystals. Additionally, we noticed a significant increase in the Optically Stimulated Luminescence (OSL) signal, indicating a greater ability of the crystals to store and release energy under optical stimulation. A particularly interesting discovery was the reduction in intensity of the third component of the OSL signal in darker-toned crystals. Also the spontaneous regeneration reported by other researchers was almost eliminated. Furthermore, our results demonstrated only a 2.5% fluctuation in experimental repeatability, indicating high consistency and reliability of the obtained data.

Correlation between figure of merit function and deviation in the assessment of kinetic parameters in realistic TLD-100 behavior using fully-connected neural networks

In this study, a realistic model was employed to research the LiF:Mg:Ti behavior (commercially known as TLD-100), a widely employed as thermoluminescent (TL) material in dosimetry services. The research was focused on exploring the association between the Figure of Merit (FOM) function and deviations from the true kinetic parameter values, that were obtained through fitting experimental measures. FOM function is the most used magnitude to measure the quality of a fit achieved between a mathematical model and experimental data. Indeed, FOM function is particularly relevant when the TL glow curve deconvolution method is implemented to obtain the kinetic parameters: Activation Energy E (eV), Frequency Factor s (s−1), value of kinetic order b, Temperature at which the intensity maximum TMax(oC), Intensity Maximum IMax (a.u.) and Distribution Width σ (eV) of every peak. FOM function is subject to degeneracy under certain conditions, this means that different sets of kinetic parameters can lead to similar FOM values. Furthermore, as the obtained kinetic parameters are deemed acceptable when the FOM value is below 5%, then the physical degeneracy is greater than the mathematical ones. This contribution provides a rigorous analysis of how the FOM values can be impacted by deviations between experimental and estimated data of kinetic parameters from the analysis process. This studio was carried out using a mathematical method based on Artificial Intelligence with a high capability to manage a large volume of data. Another advantage of this method is that the analysis to be extended to a wide range of experimental data.

Thermoluminescence studies of NaMgF3:Tb for gamma dosimetry applications

NaMgF3 is a recognized sensitive thermoluminescence (TL) dosimeter but it shows fading at room temperature which limits its use as a radiation dosimeter. It is important to improve this parameter of NaMgF3 for its potential application in the field of radiation dosimetry. Thus, the current work focuses on enhancing the dosimetric properties of NaMgF3 exclusively the TL fading characteristics. In the present study, Tb doped NaMgF3 has been synthesized by two different methods i.e. solid state reaction method (SSR) and melting method (MT). A comparative and detailed TL studies have been carried out after irradiation with gamma rays which has not been reported so far. Detailed analysis of TL and Photoluminescence (PL) properties reveal that NaMgF3:Tb prepared via MT shows good luminescence properties in comparison to SSR and previously reported results. Thus, Tb doped NaMgF3 synthesized by melting method can be a potential dosimeter for the detection of gamma rays.

A novel long persistent luminescent material CaGeO3:Tb3+ with photo-stimulation properties

A novel green long afterglow material CaGeO3:Tb3+ was synthesized by high temperature solid phase method. According to the experimental results, CaGeO3:Tb3+ is a green long persistent luminescent (LPL) material with excellent performance. CaGeO3:Tb3+ shows LPL emission peak at 442, 490.9, 548.7, 588.5 and 623.8 nm, corresponding to 5D3 to 7F4 and 5D4 to 7FJ (J = 6, 5, 4, 3) transitions of Tb3+. Its CIE coordinates are (0.27, 0.50), indicating that the afterglow emission is close to the light of green region. In addition, after the excitation source is turned off, the afterglow time is longer than 90 min. After an interval of 7 h, the photo-stimulation luminescence (PSL) can be observed by using 980 nm laser cyclic excitation. The thermoluminescence (ThL) results show that there are three types of traps in the material and their depths are 0.666, 0.774 and 0.892 eV respectively, which are caused by the doping of Tb3+. All the results show that CaGeO3:Tb3+ is an excellent long afterglow luminescent material.

Luminescence characterization of BioGlass undoped and doped with europium and silver ions

The objective of this study was to investigate the properties of BioGlass, with and without doping with europium and silver, with a specific focus on its potential application in thermoluminescent (TL) and optically stimulated luminescent (OSL) dosimetry. The structural and optical characteristics of the samples were also analyzed using techniques such as X-ray diffraction (XRD), optical absorption (OA), and fluorescence spectroscopy (FL). An XRD analysis confirmed the amorphous phase of the BioGlass. OA and FL spectra were obtained at room temperature, and characteristic bands of dopant ions were observed which confirmed the incorporation of the Eu3+ ions and silver nanoparticles Ag(NP) ion into the BioGlass. The OSL decay curves exhibited a characteristic exponential behavior, with a notable presence of fast and medium decay components; this suggests that the charge traps within the BioGlass samples possess a high photoionization cross section when exposed to blue LEDs, which are commonly used as the light source in OSL readers. Different TL glow peaks with varying shapes of the glow curve were observed when the dopant, the co-dopant, and the concentration of silver were altered in the samples. The TL kinetic parameters were determined, such as the order value, activation energy, and frequency factor, and the OSL parameters for the compound were also analyzed, including an exponential fit to the curves. Based on these initial results, we conclude that BioGlass has the potential for use in radiation dosimetry.

Persistent luminescence of commercial TLD-100 dosimeter: Using shallow traps for radiation dosimetry

This work reports the persistent luminescence (PersL) properties of the commercial LiF:Mg,Ti (TLD-100) dosimeter and its performance in dosimetry applications. The thermoluminescence (TL) glow curve of the TLD-100 exhibits a peak at 96 °C that rapidly vanishes at room temperature, enabling the PersL phenomenon. The TLD-100 was exposed to beta particle irradiation within in the range of 0.22–32 Gy. The resulting PersL intensity was measured and found to increase as the irradiation dose increased. Notably, there was no saturation of the PersL intensity within this dose range with linear dependence from 0.55 to up 32 Gy. The TLD-100 showed good repeatability with a deviation of 0.1% after seven irradiation-readout cycles for twenty irradiations. The calculated lower detection limit was 2 mGy. Our results indicate that the TLD-100 can be used as a PersL and TL dosimeter for dosimetry applications, with the advantages of fast post-irradiation measurements.