Thermoluminescence Glow Curves Research Articles

Undoped and Eu doped LaCa₄O(BO₃)₃ phosphors: Thermoluminescence characteristics with a focus on kinetic parameters, anomalous heating rate, and dose response

The thermoluminescence (TL) properties of LaCa₄O(BO₃)₃ (LACOB) phosphors, both undoped and doped with 0.5 % Eu³⁺, were synthesized using a microwave-assisted sol-gel method and analysed under beta irradiation doses ranging from 0.1 Gy to 700 Gy. The TL glow curves revealed prominent peaks at 100 °C and 285 °C for the Eu-doped sample. Activation energy values were calculated using the Hoogenstraaten and Booth-Bohun-Parfianovitch methods, yielding 1.52 eV and 1.48 eV for the undoped sample, and 2.07 eV and 2.01 eV for the Eu-doped sample, respectively. Eu³⁺ ions introduced deeper traps and enhanced the thermal stability of the material. Anomalous increases in TL intensity with rising heating rates were observed, deviating from typical thermal quenching behaviour; this phenomenon was explained using a semi-localized transition (SLT) model. The TL reusability measurements demonstrated a standard deviation of less than 5 %, indicating consistent and reliable performance across multiple cycles. The TL glow curve deconvolution identified six distinct peaks in the undoped sample, while the Eu-doped sample showed a more complex trap structure with eight peaks, indicating the introduction of additional or modified trapping sites by Eu doping. The figure of merit (FOM) values obtained from the deconvolution analysis were all below 2.5 %, indicating a good fit between the observed and fitted TL signals. These findings suggest that Eu³⁺-doped LACOB is a robust material for radiation dosimetry, with its enhanced sensitivity, stability, and versatility across various dosimetric applications.

TEMPERATURE EFFECT ON THERMOLUMINESCENCE KINETIC PARAMETERS OF NANO-ALUMINA

This research explores the fundamental thermoluminescence characteristics of irradiated nano-α-alumina particles, investigating their response to varying heating rates. The study involves recording TL luminescence curves, revealing a distinct peak with a maximum at approximately 202°C. As dose levels increase, the peak consistently shifts towards lower temperatures, indicating adherence to non-first-order kinetics (b≠1). The crystallite size was calculated using XRD analysis and estimated as 40nm. To examine the impact of the heating rate on the TL glow curve and derive kinetic parameters for nano α-Al2O3, specimens were exposed to a 6 kGy dose. Subsequently, TL glow curves were documented over a temperature range from room temperature to 300°C, employing different heating rates (2, 4, 6, 8 and 12°C/s). The peak temperature of the glow peak shifts towards higher temperatures as the heating rate increases and the peak intensity continuously diminishes, aligning with TL theory. The observed decrease in TL glow peak intensity with escalating heating rates is attributed to thermal quenching, where quenching efficiency rises at higher temperatures. Normalizing maximum TL intensities to the lowest heating rate (2°C/s) reveals a substantial 22% decrease in peak intensity.

Dy3+ doped Zn0.66Mg0.3Al2O4 nanophosphor for high dose radiation thermoluminescence dosimetric applications

Zinc Magnesium Aluminate doped with Dysprosium (Zn (1-x-y) Mg(y)Al2O4:x Dy (x=0.04 and y=0.3 mol%)) was prepared using the solution combustion synthesis method. The prepared phosphor was characterized using energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and Fourier transform infrared, respectively, to study crystal structure, surface morphology, and vibrational properties. The thermoluminescence peak temperatures were 250°C, 248°C, and 246°C at irradiating doses of 600–1000 Gy, respectively. Through the computation of the activation energy (E), order of kinetics (b), and frequency factor (s−1), the kinetic parameters were assessed using the TL glow curve. It is observed from the TL dose-response curve that the intensity rises nearly linearly for all doses between 600 and 1000 Gy. Nanophosphor Zn0.66Mg0.3Al2O4:0.04Dy shows almost linear dose-response for a dose range of 600–1000 Gy and an optimum activation energy (E) of 0.93–0.97 eV, which makes it suitable for high-dose radiation thermoluminescence dosimetric applications.

Thermoluminescence and kinetic parameters of irradiated dopant calcium aluminate nanophosphors

CaAl2O4:0.1% La nanoparticles doped with different concentrations of Mg were prepared using the sol–gel method and annealed at 400 °C, 500 °C, and 800 °C, respectively. The prepared nanophosphors show a highly crystalline orthorhombic structure with a crystallite size of about 81.2 nm. The optimum concentration of Mg dopants is about 0.7 mol%. The thermoluminescence (TL) glow curve of 11 Gy of beta-ray irradiated CaAl2O4:0.1% La:0.7% Mg measured at heating rates of 5 K/s has 16 overlapping glow peaks. The TL kinetic parameters for the prepared nanoparticles were evaluated using two different methods and they exhibited good agreement. Moreover, the linearity dose response of dosimetric peaks follows a good linearity up to 220 Gy in nanophosphor. The minimum detectable dose of the prepared nanophosphor was 125.7 mGy. The results of the prepared nanophosphors suggest good candidates for dosimetric applications.Graphical abstract

Correlation between thermoluminescence and optically stimulated luminescence of LiMgPO4:Tb,Sm,B phosphor

LiMgPO4:Tb,Sm,B is a promising material for dosimetry applications, particularly in optically stimulated luminescence (OSL). This study aimed to explore residual thermoluminescence (R-TL) glow curves after different light bleaching times to establish a connection between TL traps and OSL components for the first time. The OSL decay curves and R-TL glow curve intensities were analyzed using exponential decay functions to account for optical decay, enabling identification of the OSL components and bleaching decay rates of each TL peak. A correlation between the decay rates of OSL components and bleaching decay rates of TL peaks, as well as the relationship between increased OSL intensity and decreased TL intensity were studied for different irradiation doses. Various bleaching models were evaluated to determine the most appropriate one for LiMgPO4:Tb,Sm,B. A non-thermally sensitive deep electron trap is proposed to enhance the understanding of the luminescence mechanism in LiMgPO4:Tb,Sm,B.

Thermoluminescence and Kinetic Parameters of Beta Rays Irradiated Egyptian Muscovite.

The current work was going to study the dosimetric properties of Egyptian muscovite minerals irradiated with β-rays using the thermoluminescence technique (TL). The analysis of the TL glow curves was done using the (Tm - Tstop) and the initial rise methods. The deconvolution of the muscovite glow curves was analyzed to have eight superimposed trapping peaks. These trapes were located at 0.72, 0.80, 0.98, 1.09, 1.19, 1.30, 1.50, and 1.59 eV. Muscovite samples were studied at doses up to 330 Gy and exhibited good linearity in relation to beta radiation. The kinetic parameters, sensitivity, and dosimetric characteristics were evaluated. High accuracy was achieved through the repeatability of TL measurements.

Persistence luminescence and thermoluminescence of 260 nm UVC irradiated mixed-phase (BaAl2O4 - BaAl12O19) barium aluminate

Persistence luminescence (PerL) and thermoluminescence (TL) of BaAl2O4 - BaAl12O19 mixed phase compound under 260 nm UVC irradiation are studied. The sample shows PerL for more than 1 hour post irradiation. TL glow curves of the sample recorded at 1 oC/s following irradiation to UVC radiation shows a composite glow peak between 30 and 230 oC. The TL intensity is found to be affected by thermal quenching. The activation energy for thermal quenching is estimated to be W=0.85±0.12 eV. A Tm-Tstop analysis reveals that the TL glow peak is composed of multiple first order components. The activation energy associated with the electron traps are found to vary from 0.66 to 1.70 eV. The density of traps is high between 0.60 and 1.20 eV. Due to presence of continuous distribution of electron traps, there is an excellent scope of developing colour tuneable persistence luminescence phosphor using mixed phase barium aluminate.

Structural and luminescence properties of Y2O3:Ho3+ phosphor: Potential applications in plant cultivation LEDs and thermoluminescent dosimetry

Current research on Y2O3:Ho3+ phosphors highlight their promising luminescence properties, but often lacks an environmentally friendly synthesis method and comprehensive analysis of their applications. In this study, we address these gaps by successfully synthesizing Y2O3:Ho3+ phosphors using a green synthesis route with varying concentrations of Ho3+. Our work provides detailed characterization of their photoluminescence (PL) and thermoluminescent (TL) properties. The PL excitation (PLE) spectra reveal a distinct peak at 439 nm, attributed to the 5I8→(5K5; 5G5) transition of Ho3+ions. Upon excitation at 439 nm, the emission spectra show a sharp emission peak around 660 nm from the 5F5→5I8 transition, with the 0.1 mol% Ho3+ phosphors exhibiting particularly strong red emission, indicating their suitability for indoor plant cultivation under LED lighting. Additionally, TL properties were evaluated after gamma-ray exposure, with the highest emission intensity at 0.1 mol% Ho3+ concentration. TL glow curves were analyzed for various radiation doses using the Computerized Glow Curve Deconvolution (CGCD) method, and TL trapping parameters were determined through Chen's peak shape and the Initial Rise methods. This work demonstrates significant potential for using these phosphors to enhance indoor plant growth and for applications in thermoluminescent dosimetry (TLD).

Thermoluminescence and optically stimulated luminescence studies of Gypsum for retrospective dosimetry

This study examines the use of gypsum for radiation dosimetry using Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) techniques. It is observed that gypsum preserves the information of radiation dose despite the loss of water upon heating in a laboratory. Deconvolution of the thermoluminescence glow curve suggests thermoluminescence glow peaks at 125, 150, 280, 320, and 440 °C. The glow peak at 440 °C has a minimum detectable dose of 200 mGy, and it bleaches to approximately 50% with 300 min of daylight exposure. The Blue Light Stimulated Luminescence (BLSL) comprises a slow component and is correlated to 255 °C TL glow peak. The alpha efficiency of luminescence production per unit Gy of alpha dose with respect to the beta dose for the TL glow peaks at 440 °C is calculated at 0.18 ± 0.01. For BLSL, the value is calculated at 0.15 ± 0.01. A measurement protocol for the use of gypsum for retrospective dosimetry is also presented.

Thermoluminescence (TL) properties of Eu3+ incorporated with CaB4O7 phosphors prepared by solution-combustion process

The solution-combustion approach was used to create CaB4O7:Eu3+phosphors using Ba (NO3)2, Eu (NO3)3·5H2O, H3BO3, NH3(ON)H2, and NH4NO3 as source materials. We investigated the thermoluminescence (TL) characteristics of beta (β)-irradiated CaB4O7:Eu3+. When the TL intensity was evaluated at different dosages of β, it rose with the dose. Changes in peak temperature were observed because of the investigation of the effects of varying heating rates on TL glow curves. Moreover, the positions of the peak temperature and the TL intensity did not change when the same sample was measured again, suggesting that the sample was stable. Additionally, the study calculated several kinetic parameters, including activation energy (E), frequency factor (s), and geometrical factor (μg), for distinct TL glow curves. Through geometric analysis of TL glow peaks, the study determined activation energies and kinetic orders, enabling the calculation of the frequency factor. The findings highlight the suitability of the prepared phosphor for dosimetry and provide insights into trap characteristics crucial for continuous illumination at room temperature. The study also emphasises the importance of optimising trap depth for prolonged afterglow, shedding light on the interplay between trap energies and luminescence characteristics. These findings deepen our comprehension of phosphor behavior and open the door to better dosimetry applications.

Use of a Machine Learning based method to detect anomalous Thermoluminescence Glow Curves (TL-GC) in routine Dosimetry Services

This contribution describes the development of a set of numerical methods based on Machine Learning algorithms to generate an automated classification of experimental Thermoluminescence (TL) Glow Curves obtained routinely by Dosimetry Services. This classification will use experimental data historically recorded by Thermoluminescence Dosimeter (TLD) devices and will be based on the search for possible anomalies in the curves. The classifier tool will ease the labelling of experimental data and the detection of anomalies without previous supervision, implying an improvement in the control evaluations in Quality Guarantee Systems often implemented by Dosimetry Services. Furthermore, this study shows that each curve provides information about the status of each dosimeter, and can be used to perform unsupervised classifications of the measurements.

Thermoluminescence properties of β-ray irradiated LuAGG:Ce nanophosphors prepared by sol-gel method for potential applications in dosimetry

In this paper, Lu2.97Al5–xGaxO12:Ce0.03 (x = 0, 1, 2, 3) nanophosphors were synthesized using sol-gel method and calcined at 1100 °C for 3 h. The effect of Ga content on the structural, photoluminescence (PL), and notably thermoluminescence (TL) glow curve, dose response, repeatability and fading properties were investigated. X-ray diffraction (XRD) results indicated that all synthesized samples were crystallized in a pure garnet phase. The PL emission spectra exhibited a broad emission band corresponding to the 5 d → 4f (2F5/2, 2F7/2) transition of Ce3+ ions in the garnet lattice. Furthermore, a significant decrease in emission intensity was observed upon increasing Ga content. The TL characteristics of nanopowders irradiated with β-rays revealed a significant effect of Ga content on the peak position, shape and intensities of TL Glow curves, which can be explained by the reduction of the energy gap and the distribution of trap levels. The dose response linearity in the range of 0.125–100 Gy was examined for different Ga content, revealing a good linear behavior for x = 0 and 1 Ga. Additionally, samples prepared with x = 0, 1, and 2 Ga exhibited a high level of repeatability across a batch of 10 samples. Also, fading studies were performed for 128 h and revealed strong fading in samples synthesized with x = 0 and 1 Ga. These results suggest potential applications of Lu3Al5O12:Ce and Lu3Al4Ga1O12:Ce in ionizing radiation dosimetry.

Study on the effects of preparation processes on OSL and TL properties of NaMgF3:Dy,Eu

OSL fading with storage time after irradiation remains a major obstacle in the development of ideal OSL materials. Dy and Eu co-doped NaMgF3 are attractive candidates for various rare earth doped matrix materials. In this study, NaMgF3:Dy,Eu was synthesized by a solid-state reaction, and the effects of heating temperature, duration, atmosphere, and cooling rate on XRD, TL and OSL properties were studied. A simple, safe, efficient, and time-saving solid-state reaction was identified as a potential method for the preparation of NaMgF3:Dy,Eu, which could be optimally prepared by heating at 750 °C for 2 h under nitrogen atmosphere (2 l/min) followed by rapid cooling. The results show that NaMgF3:Dy,Eu has a more stable OSL response and an excellent TL glow curve, with only a 0.4% decrease in the OSL signal read after 1 d of dose irradiation compared to that immediately after irradiation, and a high main TL peak at ∼320 °C. It has been indicated the OSL signal in this material seems to be strongly related to the main TL peak. The material has a considerable OSL sensitivity and decay rate than the Luxel Detector. NaMgF3:Dy,Eu will have a promising future in the field of OSL dosimetry due to its near tissue equivalence, low OSL fading without preheating, fast OSL decay rate, and predictable and easily reusable dose elimination.

An investigation on thermoluminescence properties and kinetic parameters of Çankırı rock salt

This study investigates the thermoluminescence (TL) dosimetric properties and kinetic parameters of natural salt samples sourced from the Çankırı rock salt cave in Turkey using β irradiation. Obvious effective TL maximum observed at around 85 and 230°C. A preheat condition was determined to apply a thermal cleaning for the lower temperature side of TL spectrum. Dose sensitivity, linearity and reusability characteristics were investigated for effective TL maximum on the high temperature side of the spectrum. TL kinetic parameters were determined via various heating rates (VHR) experiment, and whole TL glow curve was studied via Tm−Tstop experiment and glow curve deconvolution. General order kinetics approach was utilized for glow curve deconvolution analysis. Kinetic parameters were determined for at least eight electron trap levels which has activation energies in the range of 0.8–1.53 eV.

Exploring γ and UV irradiation responses on thermoluminescence and optical thermometry studies on Y4Al2O9:Ho3+ nanophosphor

A series of green emitting Ho3+ (1–9 mol%) doped Y4Al2O9 nanophosphors (NPs) are synthesized via solution combustion technique. Photoluminescence (PL) studies shows emission peaks recorded at ∼ 522 nm (5F3→5I8), 545 (5F4, 5S2→5I8), 659 (5F5→5I8) and 730 (5F4→5I7) upon excited at 460 nm wavelength. With a tremendous potential for application in white light-emitting diodes (w-LEDs), the phosphors show a bright green emission under 460 nm excitation. They also have a notable activation energy (0.31 eV), high color purity (98.2 %), and a remarkable quantum yield (87.1 %). Most astonishingly, even at temperatures as high as 420 K, YAO:5Ho3+nanoparticles retain 88.9 % of their initial fluorescence intensity. Using the fluorescence intensity ratio (FIR) method, the temperature sensing potential is also investigated. Thermoluminescence (TL) glow curves of γ (1 kGy) and UV (1 h) irradiated YAO:Ho3+(1–9 mol%) NPs exhibit two glow curves and highest intensity is recorded for YAO:5Ho3+NPs. TL characteristics of 5 mol% Ho3+ doped YAO NPs are subjected to γ (1 Gy-5 kGy) and UV (0.25–6 h) irradiation. Two glow curves recorded at 475 K (major peak) and 567 K (shouldered peak) for γ irradiation. However, for UV irradiation two glow curves at 478 K (major peak) and 575 K (shouldered peak) are recorded utilizing a 5 °C per minute heating rate. TL intensity varies with γ and UV exposure is recorded for optimized NPs and major glow peaks showcase linear response for both γ and UV irradiations, indicating that the prepared phosphor can be used in TL personal dosimetry. Furthermore, compared to γ-irradiated phosphor, UV-irradiated phosphor shows greater fading. The overall results clearly demonstrate that the optimized phosphor has proven to be an outstanding candidate for multifunctional applications.

High quantum yield luminescence and scintillation properties of high-Ce-doped MgF2–Al2O3–B2O3 glasses and their glass structure

Ce-doped inorganic single crystals are currently used in scintillators in various instruments because of their outstanding luminescence properties. However, these crystals are expensive to manufacture and are inefficient in terms of their energy consumption. In this study, xCeF3-doped 40MgF2–20Al2O3–40B2O3 glasses (x = 0−30 mol%) were prepared by a melt-quenching method in N2 atmosphere, and their photoluminescence, scintillation, and dosimetry properties were investigated. The X-ray absorption fine edge spectroscopy of the Ce L3-edge indicated that the doped Ce exists in the form of Ce3+ ions, and that Ce4+ does not form because of the low basicity of the glass. The glasses underwent photoluminescence at 380 nm due to the 5d-4f transition of Ce3+, with a very high quantum yield of up to ∼100 % and low concentration quenching. The peak shape of the X-ray-induced luminescence was similar to that of the PL with a decay time of 110−70 ns. The light yields for gamma rays (137Cs source) were obtained from the pulse-height spectra, and the highest light yield among the present samples was 1071 photons/MeV with the energy resolution of 17 %. The thermoluminescence glow curves had peaks at 365 and 460 K and a good linear relationship existed in the range of 0.5–1000 mGy, with the dose response being comparable to that of a commercial dosimeter. The origin of the high quantum yield was probed by analyzing the glass structure using molecular dynamics simulation based on a graph neural network. A strong tendency to selectively bind cations and anion pairs was found: Mg preferably binds to F, B preferably binds to O, and Al binds to O and F, which can be explained by soft and hard acid and base theories. Because of this selectivity the glass forms fluoride- and oxide-rich domains, which seem to be responsible for the more effective dispersal of the luminescent center. The results of this study are expected to contribute to the development of glasses with enhanced photoluminescence and scintillation luminescence properties.

Fabrication and investigation of thermoluminescence properties of Zn2SiO4/SiO2 nanophosphor with manganese impurity

Considering the widespread use of radioactive materials and ionizing rays in most fields, such as agriculture, medicine, industry, and energy supply, The presence of a dosimeter is necessary to measure the dose of these rays to reduce their damage. The present study involves the synthesis of Zn2SiO4/SiO2:Mn nanophosphors utilizing ZnC4H6O4 powder, NaOH, and SiO2, followed by heating at 950 °C to develop a thermoluminescence dosimeter for potential use in various applications. Structure and morphology of the Zn2SiO4/SiO2:Mn nanophosphor were studied utilizing techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The thermoluminescence (TL) glow curves of the Zn2SiO4/SiO2:Mn nanophosphor were meticulously analyzed under controlled laboratory conditions. Analysis results revealed that the nanophosphor has a remarkable sensitivity towards low doses of ultraviolet rays. The study demonstrated the effectiveness of Zn2SiO4/SiO2:Mn nanophosphor in detecting and measuring ultraviolet radiation.

Synthesis and thermoluminescence characterization of either Cu- or Ag-doped lithium triborate

Lithium Triborate (LiB3O5 or LTB), is characterized by chemical stability and good mechanical properties, and it has an effective atomic number (Zeff = 7.39) close to that of the human tissue (Zeff = 7.42), making it a potential dosimeter. The objective of this research is to examine the Thermoluminescence (TL) features and dosimetric characteristics of both Cu-doped and Ag-doped LTB. The material was synthesized using the solid-state synthesis method and four different dopant levels were used for each element (0.1%, 0.5%, 1%, 3%); various techniques such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy were used for structural and compositional characterization, for samples annealed at 500 °C for 1 h in all cases. Specific TL features were studied, such as TL glow curve shape, sensitization and sensitivity, fading behavior as well as kinetic characterization using two supplementary techniques, namely fractional glow technique and deconvolution analysis. The effect of each dopant element is different in the (same) lithium triborate matrix in terms of sensitivity. TL dosimetric peaks are yielded for both dopant elements; however, the optimum doping level is 3% for Ag but just 0.1% for Cu. Furthermore, the samples were irradiated at different doses, ranging from 0.5 to 2048 Gy, in order to study the corresponding dose response. A remarkable dose response linearity was observed for the main dosimetric peak of both materials, ranging up to ∼1 kGy.The fading results suggest that LTB doped with 0.1% Cu is the most promising material for dosimetric applications.

Study of Thermoluminescence and Optically Stimulated Luminescence Properties of Synthesised CaB2O4 Nanoparticles Doped with Copper.

CaB2O4 nanorods doped with different concentrations of Cu were prepared by using co-precipitation method. The recorded Thermoluminescence (TL) and Optically stimulated luminescence (OSL) of CaB2O4:Cu samples for different concentrations of Cu irradiated with 6Gy of X-Ray shows that 0.05 at.wt% of Cu concentrations have higher sensitivity. The TL and OSL kinetic parameters of glow curves were evaluated using "tgcd" and conventional fitting methods. The TL glow curve of the CaB2O4:Cu have three individual glow peaks with maximum peak temperatures at 404.50, 453.04 and 484.02K respectively. The OSL glow curves of the CaB2O4:Cu nanoparticles follow non-first order kinetics which can be fitted with the sum of two first order decay curves.

Exploring the thermoluminescence characteristics of smartphone screen safety glasses for retrospective dosimetry applications

In clinical settings, standard dosimeters might miss radiation mishaps. Retrospective dosimeters could help to track personnel (such as patients and other staff who don't wear dosimeters) exceeding safe limits and assess long-term exposure trends. This study has investigated key thermoluminescence (TL) dosimetric characteristics, including the glow curve structure, dose-response, energy dependence, sensitivity and fading of various safety glasses that are used as screen protectors of smartphones subjected to photon irradiation. Among the studied glasses, the HD Anti-Peep safety glass for iPhone has been found to exhibit a linear dose-response with a regression coefficient of 99% within the dose range of 2–10 Gy. Moreover, all the safety glasses showed independence with respect to photon energy of 6 MV and 10 MV. The TL glow curves of the samples showed a broad glow peak between 125 °C and 325 °C at 10 Gy. The TL kinetic parameters of the safety glasses were also studied by analyzing the glow curves using the peak shape and initial rise method. The geometric factor (μg) is found to be within the range of 0.43–0.53, which indicates the suitability of applying Chen's general-order formula to calculate the kinetic parameters such as activation energy, frequency factor and trap lifetime. The activation energy (E) and frequency factor (s) are found in the range of 0.31–0.54 eV and 4.55 × 103 to 2.12 × 106 s−1 respectively obtained via the peak shape method. The relatively long trap lifetime and observed thermoluminescence features indicate that the HD Anti-Peep safety glass offers a better option to estimate dose retrospectively to ensure the safety of human health.