Computerized Glow Curve Deconvolution Research Articles

Extended study of the influence of europium doping on phosphate glass

The phosphate glasses with various Eu2O3 concentrations (0.1–3.0 w/w%) were synthesized and studied regarding the influence of europium dopant on the properties of irradiated phosphate glasses. During studies, samples were irradiated using two types of ionizing radiation sources (β− and γ), with obtained doses up to 40 kGy. TL studies were investigated using various methods, such as TL response vs. radiation dose and the TMax-Tstop method. To further investigate, if increasing the europium concentration affects the structure of electron traps, Computer Glow Curve Deconvolution studies linked with various heating rates methods were applied –increasing the concentration of dopant does not influence the number and energy of electron traps in irradiated samples. This fact was also supported by the results of the thermoluminescence spectrum – where no additional signals, besides wide signals from native glass were observed. OSL and IRSL studies were also conducted, for OSL we observed quenching of the signals, similar as in the TLD case. For IRSL studies all samples didn't display any signals. Finally, to understand if Eu3+ also has a “protective” effect, decreasing the yield of generating F-centers during irradiation, UV-VIS spectroscopy was used. It was established that samples doped with europium oxide possess ca. 20% lower signals at F-center maximum (at 475 nm), the building-up maximum at 320 nm was observed, characteristic of the absorption band of Eu2+. All data indicate that europium in phosphate glass is taking the role of an efficient electron quencher. This quenching phenomenon occurs in three ways: first (direct) when the ion reduction process (Eu3+→Eu2+) competes with the formation of F-centers, and second (indirect) when during heating electrons coming from F-centers were quenched by near Eu3+ ions. The third mechanism of quenching occurs through the electron's non-radiative transition induced by increased stress in the glass matrix caused by a large ionic radius of the dopant.

Beta irradiation-induced thermoluminescence: Glow curve analysis and kinetic parameters in combustion-synthesized undoped Ca4YO(BO3)3

This study examines the thermoluminescent (TL) properties of undoped Ca4YO(BO3)3 phosphor, focusing on how it behaves under a variety of experimental conditions. The IRSL-TL 565 nm was chosen as the appropriate detection filter among various optical detection filter combinations. During the preheating trials conducted at a rate of 2 °C/s, the TL peak exhibited increased intensity, particularly around 200 °C. The experimental outcomes demonstrated a reliable linear relationship (R2 = 0.996 and b = 1.015) in the dose response of undoped preheated Ca4YO(BO3)3 within the range of 1–200 Gy. The investigation encompasses a range of techniques, including the TM-Tstop method, computerized glow curve deconvolution (CGCD) analysis, and theoretical modelling. The application of the TM-Tstop method to samples irradiated with a 5 Gy dose revealed distinct zones on the TM versus Tstop diagram, signifying the presence of at least two discernible components within the TL glow curve, specifically, a single general order kinetics peak and a continuous distribution. The analysis of activation energy versus preheated temperature exhibited a stepwise curve, indicating five trap levels with depths ranging between 1.13 eV and 1.40 eV. The CGCD method also revealed the superposition of at least five distinct TL glow peaks. It was observed that their activation energies were consistent with the Tm-Tstop experiment. Furthermore, the low Figure of Merit (FOM) value of 1.18% indicates high reliability in the goodness-of-fit measure. These findings affirm the reliability and effectiveness of the employed methods in characterizing the TL properties of the Ca4YO(BO3)3 phosphor under investigation. Theoretical models, including the semi-localized transition model, were introduced to explain anomalous observations in TL glow peak intensities and heating rate patterns. While providing a conceptual framework, these models may require adjustments to accurately capture the specific characteristics uncovered through CGCD analysis. As a potential application, the study suggests that the characterized TL properties of Ca4YO(BO3)3 phosphor could be utilized in dosimetric applications, such as radiation dose measurements, owing to its reliable linear response within a broad dose range.

Luminescence properties of Ce and Be-doped CaAl12O19 for dosimetric and light-emitting applications

In this study, we reported the sol-gel production of cerium (Ce) and beryllium (Be)-doped calcium aluminate (CaAl12O19) and its luminescence properties for optically stimulated luminescence (OSL) dosimetry and light-emitting applications. Structural, morphological and elemental characteristics of the samples were examined by x-ray diffraction (XRD), Scanning electron microscope (SEM)/energy dispersive spectrum (EDS), x-ray fluorescence (XRF) and Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) techniques. The maximum OSL intensity was achieved with 0.5 and 2% mol concentrations of Ce and Be dopants, respectively. We investigated the OSL and thermoluminescence (TL) properties of Ce and Be-doped CaAl12O19 by measuring energy storage for 24 h, dose-response in the range of 0.1 and 20 Gy, and reusability of the samples for 15 cycles. Photometric properties of the phosphors were investigated by evaluation of CIE chromaticity coordinate (x, y), CCT, and colour purity using its corresponding photoluminescence (PL) emission spectra. We also applied computerized glow curve deconvolution (CGCD), various heating rate methods, and the Tm-Tstop procedure to determine the trap localizations associated with the TL glow curve. The results of this study point out that CaAl12O19 crystals have the potential to be used as OSL dosimetry when appropriate dopants are used. This study may offer new possibilities in radiation dose detection and monitoring.

Thermoluminescence characteristics of gamma-irradiated nano-alumina

The focus of this study lies in exploring the properties of thermoluminescence (TL) in nano-alumina, including the correlation between TL intensity and absorbed dose, identification of individual luminescence peaks, and investigation of trap parameters for potential dosimetry applications. The samples were irradiated by 60Co with doses ranging from 530 to 2646 Gy. Micro-sized α-Al2O3 had a prominent dosimetry peak at maximum temperature Tm = 435 K. Nano-α-Al2O3 samples with 40 and 50 nm particle sizes exhibited a TL luminescence glow curve, with the main dosimetry peak in the low-temperature region and a complex structure at higher temperatures (above 500 K). The observed maximum of the main dosimetry peak depended on the nanoparticle size and was 460 K for the sample with particle size of 40 nm and 467 K for 50 nm. The main dosimetry peak was described by the superposition of the two peaks.A computerized glow curve deconvolution method was applied to determine the parameters of the traps responsible for TL using the Microsoft Windows-operated GlowFit program, assuming first-order kinetics. The found values of the activation energies were 0.97 ± 0.01 eV for the trapping center responsible for the peak with Tm = 458 ± 3 K and, accordingly, 1.05 eV for the peak with Tm = 473 ± 3 K. The estimated values of the frequency factor were s ≈ 1.01 × 1010 and 1.3 × 1010 s−1 for the peak with Tm = 458 ± 3 K, and 2.06 × 1011 s−1 for the peak with Tm = 473 ± 3K, respectively. The lifetime for the traps in nano-α-Al2O3 was estimated as 43–56 days for the first trap and approximately 65 days for the second trap. It is assumed that these traps are responsible for TL emission at the low-temperature part of the glow curve.

Synthesis and thermoluminescence characteristics of beta irradiated nanocrystalline calcium aluminate doped with lanthanum oxides

This study investigated the thermoluminescence (TL) characteristics of calcium, a nano-phosphor doped with a rare earth element (lanthanum, La). Six different concentrations of dopants were prepared by the sol-gel method. The XRD data displayed that the particle size was 52.48 nm. The surface morphology was examined by SEM analysis. The highest TL response of the nano-phosphor CaAl2O4 was found with a dopant of 0.1 % La, which has the most intense TL peak. The Computerized Glow Curve Deconvolution (CGCD) and Variable Heating Rate (VHR) methods were carried out for trap-level analyses and activation energy determination. The deconvolution of the glow curves displayed thirteen superimposed TL glow peaks located between 362 and 717 K. The TL response of CaAl2O4:0.1 % La nano-phosphor showed linearity in the beta dose range from 2.2 Gy up to 330 Gy for all the deconvoluted glow peaks. The minimum detectable dose of the prepared samples is 284 μGy. Other parameters, such as the sensitivity and reproducibility of the prepared samples, were determined. It is concluded that CaAl2O4 with a dopant of 0.1 % La is a good material for dosimetry applications.

B2O3–TeO2–ZnO–Na2O–Nd2O3 glass matrices: A comprehensive study of physical, structural, optical, and thermoluminescence properties

The present study reveals the effect of Nd3+ in sodium zinc borotellurite glasses for photonic and dosimetric applications. The melt quenching technique was employed to prepare glass samples for different Nd2O3 compositions (0.0–1.0 mol%) with the empirical chemical relation (60-x)B2O3+20TeO2+10ZnO+10Na2O+xNd2O3. The glass samples were characterized via different techniques for their physical, structural, optical and thermoluminescence behaviour. The Archimede's principle was used to analyse the physical parameters, including density (ρ), molar volume (Vm), and oxygen packing density (OPD). XRD spectra indicated the amorphous nature of fabricated glasses and Fourier transform infrared spectroscopy (FTIR) revealed ZnO, TeO3, TeO4, BO3, BO4 units and Nd–O bonds present in the glass matrix. The values for indirect (Eopt1) gap, Urbach energy (ΔE), cut-off wavelength (λc) and other optical parameters were determined from the optical absorption spectra. Thermoluminescence (TL) response of the prepared glasses was analyzed for gamma dose of 1 kGy–13 kGy, among which NBT 0.2 glass sample showed strongest TL intensity at 5 kGy with non-monotonic behaviour. With the use of Computerised Glow Curve Deconvolution (CGCD), various trap parameters, including activation energy (E), order of kinetics (b) and frequency factor (s) have been identified. Low effective atomic number of these glasses, along with their optimal TL response makes them effective for radiation monitoring, pasteurization of sea food and decomposition of drugs at high doses.

Luminescence characteristics and kinetic parameters of LiBaPO4: Tb3+, Dy3+ phosphors synthesized by sol-gel method

LiBaPO4: Tb3+, Dy3+ phosphors were prepared via sol-gel method by using the stoichiometric amounts of lithium nitrate LiNO3, barium nitrate Ba(NO3)2 and ammonium dihydrogen phosphate NH4H2PO4 as base materials. Morphology by scanning electron microscopy (SEM), structure by X-ray diffraction (XRD), thermal properties by Differential thermal analysis (DTA)/Thermogravimetric Analysis (TGA) and structural characteristics by Fourier transform infrared spectroscopy (FT-IR) were investigated. This paper presents luminescence properties using spectra from radioluminescence (RL), photoluminescence (PL), cathodoluminescence (CL) and, thermoluminescence (TL) and the influence of RE dopants (Tb3+, Dy3+) on the luminescent behavior of LiBaPO4. Computerized Glow Curve Deconvolution (CGCD) and Peak Shape Method were used to determine the kinetic parameters and the obtained results were evaluated. The RL results of un-doped LiBaPO4 showed the presence of a well-defined peak at 417 nm and a weaker band around 685 nm. Strong emissions were detected in the sample doped with Dy3+ correspond to 4F9/2→6Hj transitions. Blue, yellow and red emissions were observed with transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2, respectively. As for LiBaPO4: Tb3+, green emissions originated from the characteristic transitions (5D3 → 7FJ (j = 6–3) and 5D4 → 7FJ (j = 6–1)) of Tb+3 ion was seen. The RL, PL and CL spectra were identical, suggesting these green emissions. Dy3+ doped sample has three glow curves located at 72 °C, 145 °C and 204 °C, while the main temperature peak is measured at 240 °C for Tb3+ doped sample. Chromotographic studies of LiBa0·98PO4: Dy3+0.02 reveals that calculated x and y color coordinates (0.3122, 0.3233) are very close to the white light.

Thermoluminescence studies of Pakistani limestone pellets for X-rays

The quest to identify low-cost thermoluminescence (TL) materials is vital, and the identification and assessment of natural materials suitable for radiation detection is a rapidly growing area of research. In addition to their specific dosimetric characteristics, such materials must be rigid, insoluble, and chemically inert. One such promising low-cost material can be a limestone having vast deposits in Pakistan. The present study reports the TL and dosimetric features of Pakistani limestone pellets and their comparison with TLD-100.The quarried crystalline limestone rock was hand crushed, sieved, and compressed into the standard TLD chip-sized pellets. The TL response, kinetic parameters, batch homogeneity, dose linearity, individual sensitivity correction factor (i.e., elemental correction coefficient ECC), lowest detectable dose limit (LDDL), coefficient of variation (COV), energy dependency, and fading were determined, and compared with TLD-100. For TL analysis, the pellets were exposed to an 8 Gy dose of 250 kVp X-rays. These exhibited complex TL showing four peaks (P1: 90–110 °C, P2: 130–170 °C, P3: 240–280 °C and P4: 320–350 °C). The limestone response was linear in the studied dose range of X-rays (1–10 Gy), unlike the supra-linear behavior of TLD-100. The kinetic parameters (i.e., the frequency factor (f), activation energy (E), and the kinetic order (b)) were estimated through computerized glow curve deconvolution using the general order of kinetics while confirmed by the Tm-Tstop method. The values of E and f were observed in the ranges of 0.85–1.27 eV and 5.98 × 107 to 1.81 × 1013 s−1, respectively. The calculated value of figure-of-merit (FOM) (i.e., 2.37%) showed a good agreement between the experimental and fitted glow curves. The overall variation in the ECCs for TLD-100 and limestone was found within ±4% and ±7%, respectively. The results of the ECC confirmed batch homogeneity. The calculated value of LDDL was ∼1.01 Gy. The investigation found that the maximum variation in normalized intensity and COV was within the tolerance limit of 5%. The limestone pellets showed less sensitivity than TLD-100. Like TLD-100 at high energy, the pellets showed an independent response. In contrast to TLD-100, the limestone pellets showed a higher response dependency for low-energy X-rays.During the fading study, the total TL intensity decreased by 20% within the initial 24 h of irradiation and then sustained stability for the subsequent week. The results of this study indicate that limestone pellets are effective as an X-ray dosimeter for doses between 1 and 10 Gy.

Influence of Annealing Temperature on the Structural and Luminescence Features and Thermoluminescence Trap Parameters of Ca2Al2SiO7: Ce3+ Phosphors

Cerium-doped Ca2Al2SiO7 phosphors were synthesized via the combustion technique and annealed at 1073 K, 1173 K, and 1373 K. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), photoluminescence (PL), and thermoluminescence (TL) studies were performed to explore the variation of structural, morphological, luminescence, and TL properties with annealing temperature. The XRD plot showed an increase in crystallinity with an increase in annealing temperature. Similarly, the enhancement of PL intensity with an increase in annealing temperature supports the increased crystallinity of the phosphor samples. Detailed analysis of traps and trap parameters was carried out using the principle of TL. Samples were irradiated with different γ-ray doses, and, on heating, luminescence was observed. Thus, TL glow curves were drawn and deconvoluted using computerized glow curve deconvolution (CGCD) and Chen’s peak shape method to study the traps and trap parameters. With increasing annealing temperature, an increase in TL intensity was observed. Regardless of annealing temperature, every sample displayed a linear dose–response for doses ranging from 3 Gy to 500 Gy. TL investigations suggested that the produced phosphors are suitable candidates for gamma dosimetry applications.

Anomalous heating rate effect in GdAl3(BO3)4:Dy3+ under beta radiation stimulation: Analysis of dose response and kinetic parameters

This study presents a comprehensive investigation into the thermoluminescence (TL) properties of Dy3+-activated gadolinium aluminate garnet (Dy3+:GdAl3(BO3)4 or Dy3+-GAB) phosphor materials. The research aims to unravel the intricate interplay among heating rate, radiation dose, and TL glow curve responses to optimize dosimetry applications. The TL response of the material is scrutinized across diverse heating rates (HR) and dose levels, while accounting for temperature lag correction. Concentration quenching effects are explored through Dy3+ concentrations spanning from 0.5 to 7 wt%, revealing the optimal doping concentration to be 3 wt%. The study underscores the critical role of choosing an appropriate band-pass filter, revealing the effectiveness of the “IRSL-TL wideband blue” filter's in capturing TL signals. Furthermore, the study examines kinetic parameter estimated using different approaches and shedding light on how heating rate and radiation dose affect activation energy values. Intriguingly, the study observes an anomalous heating rate effect, resulting in elevated TL peak intensities at higher HR. This effect is attributed to non-radiative transitions and the semi-localized transition model. The reusability of Dy3+-doped GAB is also examined, confirming its consistency and reproducibility across multiple uses. This study significantly contributes to the advancement of TL dosimetry methodologies and enhances our understanding of luminescent material behaviours. We utilized both the Tm-Tstop technique in conjunction with the Initial Rise (IR) method and Computerized Glow Curve Deconvolution (CGCD) techniques, revealing the presence of seven overlapping glow peaks alongside the main ones. Both methods appear to provide excellent agreement in terms of activation energy values, ranging from 0.70 to 1.50 eV for each peak. Furthermore, the findings strongly indicate the effective utilization of TL signals in radiation dosimetry applications.

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.

UV irradiated thermally stimulated luminescence investigation of SrWO4: Pr3+ phosphor

The article explores the thermally stimulated luminescence (TSL) properties of SrWO4: Pr3+ phosphor. The material exhibits excellent glow response due to the presence of traps after excitation at 254 nm UV light. The effect of change of linear heating rate and irradiation doses on TSL glow curve parameters is explained properly. The reusability of the material is ensured by repeating the same measurement several times. Trap parameters are calculated using computerized glow curve deconvolution (CGCD) mthod by considering the general order kinetics of the peaks.

Investigation in dosimetric properties of α-Al2O3 luminescence dosimeters for diagnostic radiology energy range

In this study, the TL dosimetric properties of α-Al2O3:C dosimeters were investigated within the diagnostic radiology energy range, using different radiation sources (beta, gamma, and X-ray). The TL glow curve kinetic parameters of the dosimeter were calculated using different methods such as initial rise, fractional glow, various heating rates and numerical methods of computerized glow curve deconvolution (CGCD) and peak shape (PS) methods. As a result, the activation energy of the dosimetric TL peak, (Tmax = 170 °C) was obtained as ⁓1.28 eV with 25% uncertainty in all methods. Furthermore, the dosimetric properties of this dosimeter, essentially dose response, energy dependency, fading effect, repeatability, and minimum detectable dose, were investigated. For high doses under a beta source (1 Gy–1 kGy) a linear behavior up to 40 Gy was observed, on the other hand, perfect linear response was obtained for all three X-ray energies (60, 80, 100 kVp). In addition to those two parts, the handling and light-induced effect of the dosimeter were investigated for daylight, ultraviolet lamp (UV-254 nm) fluorescent, and red and blue LEDs. The results of the light-induced effect following irradiation showed that the TL intensity was rapidly affected in the case of daylight, exhibiting a reduction of ⁓99% after 30 min of exposure. The effect of red and blue LEDs was observed to be approximately ⁓58% and ⁓64%, respectively. However, relatively less intensity loss was observed for ultraviolet and fluorescent after 120 min, with values of 75% and 39%, respectively.

Thermoluminescence behavior of Ce3+ doped lanthanum tri-borate phosphor for dosimetry applications

The combustion method was used to synthesize Ce3+ doped LaB3O6 phosphors in a range of dopant concentrations. Both the un-doped and Ce3+ doped LaB3O6 samples matched the required reference card, according to X-ray diffraction patterns. TL glow curves of Ce3+ doped LaB3O6 samples at various dopant concentrations were examined by employing various optical detection filter combinations to define TL characteristics. LaB3O6:Ce3+ (1%) and IRSL-TL 565 nm were selected as the suitable sample and appropriate detection filter pairing. The TL maximum with a higher intensity was seen during preheating trials (with 2 °Cs−1) at around 270 °C. The experimental results showed feasible linearity (R2 = 0.998 and b = 1.054) between 5 and 1000 Gy for the dose response of LaB3O6:Ce3+ (1%). The short-term fading test was conducted at various time intervals up to a week. The findings showed that the dosimetric peak strength was almost constant for up to 5 days. However, an additional spurious maximum appeared at the higher temperature zone. Each sample showed an abnormal heating rate effect, which can be explained by localized electrons caught in the intermediate excited state, which is capable of radiative transitions via the conduction band. To find the overlapping peak numbers and determine the kinetic parameters of preheated LaB3O6:Ce3+ (1%), various heating rates, TM-Ts, initial rise, and computerized glow curve deconvolution techniques were utilized. The results suggest that LaB3O6:Ce3+ may be an appropriate material for TL dosimetry applications due to its efficient TL characteristics.

Unravelling the impact of unusual heating rate, dose-response and trap parameters on the thermoluminescence of Sm3+ activated GdAl3(BO3)4 phosphors exposed to beta particle irradiation

The thermoluminescence of GdAl3(BO3)4 (GAB) doped with various concentrations of Sm3+ (i.e. from 0.5 to 7 wt%), prepared by gel combustion, was studied. TL glow peaks at 78 °C and 225 °C are observed. The intensity of the glow peak at 225 °C increased with a faster heating rate. To gain insight into the trap activation energies, the methods of Hoogenstraaten and Booth-Bohun-Parfianovitch were used, where the calculated activation energies are 0.57 eV and 0.60 eV for Peak I and 1.69 eV and 1.71 eV for Peak II respectively. The dose-response of GAB:0.5 wt%Sm3+ demonstrates robust linearity up to 40 Gy, with a strong correlation coefficient of 0.999. Both TM-Tstop combined with the Initial Rise (IR) and Computerized Glow Curve Deconvolution (CGCD) techniques were employed, which revealed six overlapping glow peaks beneath the main peaks. Additionally, the results suggest that the TL signal can be efficiently exploited for radiation dosimetry applications.

Intense green light emission and thermoluminescence glow curve analysis of Tb3+ -activated CaY2 O4 phosphor.

Here, the synthesis and luminescence analysis of the Tb3+ -activated phosphor were reported. The CaY2 O4 phosphors were synthesized using a modified solid-state reaction method with a variable doping concentration of Tb3+ ion (0.1-2.5mol%). As synthesized, the phosphor was characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis techniques for the optimized concentration of doping ions. The prepared phosphor showed a cubic structure, and FTIR analysis confirmed functional group analysis. It was discovered that the intensity of 1.5mol% was higher than at other concentrations after the photoluminescence (PL) excitation and emission spectra were recorded for different concentrations of doping ions. The excitation was monitored at 542 nm, and the emission was monitored at 237 nm. At 237 nm excitation, the emission peaks were found at 620 nm (5 D4 →7 F3 ), 582 nm (5 D4 →7 F4 ), 542 nm (5 D4 →7 F5 ), and 484 nm (5 D4 →7 F6 ). The 1931 CIE (x, y) chromaticity coordinates showed the distribution of the spectral region calculated from the PL emission spectra. The values of (x = 0.34 and y = 0.60) were very close to dark green emission. Therefore, the produced phosphor would be very useful for light-emitting diode (green component) applications. Thermoluminescence glow curve analysis for various concentrations of doping ions and various ultraviolet (UV) exposure times was carried out, and a single broad peak was found at 252°C. The computerized glow curve deconvolution method was used to obtain the related kinetic parameters. The prepared phosphor exhibited an excellent response to UV dose and could be useful for UV ray dosimetry.

Nanostructured TLDs: Studying the impact of crystalline size on the Thermoluminescence glow-curve shape and electron trapping parameters

Nanostructured thermoluminescent dosimeters (TLDs) and their relevance in the field of Stimulated Luminescence has grown over the past years. Particularly, since preparation methods and characterization techniques have been improved, while their integration in technological advancements which has also significantly increased. Despite the numerous case studies dealing with applications and properties of nanomaterials, there is a limited number of studies investigating cases from a basic research point of view, like studying the transition of a material from bulk to nanoscale and the dominant features of this transition. Specifically, in Thermally Stimulated Luminescence or Thermoluminescence (TL), the extensive study via geometrical signal processing with the well-established techniques of Peak Shape Methods (PSM) and Computerized Glow-Curve Deconvolution (CGCD), and the estimation of trapping parameters of certain TL peaks, along with possible dependence of the activation energy of electron traps inside the crystal structure for different crystalline sizes, are missing from the literature. The present study includes several popular TLDs like BeO, LiF, CaSO4 and other more complex crystal structures such as NaLi2PO4, K2Ca2(SO4)3, LiNaSO4 and a geological Fluorapatite in different crystalline size fractions. Special emphasis has been devoted to the estimation of activation energies and the geometrical characteristics in the nanoscale by analyzing each TL signal accordingly. While the analysis imposes several interesting cases on the implementation of the results, the study has shown that under different crystalline sizes, most of materials follow a normal downtrend on their signal with some insignificant alterations on their physical parameters.

Determination of the kinetic parameters of BeO luminescent material using different methods towards X-ray irradiation

In this work, the thermoluminescence (TL) and optically stimulated luminescence (OSL) kinetics of a recently developed beryllium-oxide dosimeter (BeOR) were studied with different methods. The TL and OSL dose responses were also established for an X-ray dose interval of 2–10 Gy. The TL kinetic parameters were determined using three methods, namely: the peak shape (PS), the first-order kinetics (FOK) using Glow-Fit, and the general-order kinetics (GOK) using computerized glow-curve deconvolution (CGCD). TL glow curves of the irradiated BeOR show two distinct TL experimental peaks at ∼250 and ∼379 °C under a heating rate of 5 °C/s. The PS method demonstrates a kinetics order of about two (∼2) for the first peak, whereas the second peak follows first-order kinetics. The activation energies resulting from PS method range from 0.98±0.03 to 1.01±0.05 eV for the first peak and from 1.56±0.07 to 1.58±0.08 for the second peak. The FOK-Glow-Fit show three deconvolution peaks (1.02, 1.05, and 1.07 eV) for the first TL experimental peak and one peak (1.94 eV) for the second experimental peak. The GOK-CGCD method reveals three peaks of ∼1.04, 1.6 (experimental peak1), and ∼2.1 eV (experimental peak2). The TL kinetic parameters were established and compared for the three considered methods. Based on the TL kinetics study, OSL kinetics parameters of BeOR were also determined. The established TL and OSL dose responses of studied dosimeter show linear behaviour that allow effective dosimetry application in photon radiotherapy.

Photoluminescence and thermoluminescence kinetic features of Eu3+ doped Sr2YVO6 double perovskite phosphor

Through traditional high-temperature combustion synthesis, a series of luminescent orange-red emitting Sr2YVO6:Eu3+ double perovskite phosphors were prepared, and their luminescence properties were examined. Through X-ray diffraction (XRD) and Rietveld analysis, the monoclinic crystal structure of all prepared Sr2YVO6:Eu3+ phosphors were confirmed. Scanning electron microscopy (SEM) was used to analyse the morphology of the phosphor. Under 320 nm excitation, Eu3+ doped Sr2YVO6 phosphors exhibit very strong red photoluminescence (PL) emission bands at 595 nm, 616 nm and 620 nm as well as distinct red emission bands at 653 nm and 699 nm, which are originated due to the 5D0-7FJ (J = 1,2,3,4) transition of Eu3+. A series of phosphor also exhibit orange-red emission at 595 nm, 612 nm, 616 nm and 620 nm under the excitation wavelength of 396 nm. High color purity of the phosphors is revealed by calculated color purity and excellent chromaticity coordinates, which also confirms the presence of far-red luminescence emission. After the irradiation of the phosphors at various beta doses via 90Sr/90Y beta source, the thermoluminescence (TL) studies of Eu3+ activated Sr2YVO6 phosphors was conducted. Exposer of beta irradiation revises a prominent TL glow curve at 124 °C with a small hump at around 290 °C, indicating the development of different trap centres in the phosphor. As the dose of beta radiation increased, a linear dose response was observed in TL intensity. Computerised Glow Curve Deconvolution (CGCD) method and Chen's Peak Shape Method (PSM) were used to determine the activation energies and trapping parameters of TL glow curves. According to CGCD fitting of TL glow curves, it is found that all glow curves consist of five deconvoluted peaks, which follows general order kinetics. Activation energies calculated through different methods were comparable and significant.

Thermoluminescence and optically stimulated luminescence properties of NaMgF3:Dy,Eu synthesized by hydrothermal method and DFT calculations for the bandgap

This study indicates Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) radiation dosimetry characteristics for NaMgF3:Dy1%,Eu0.1% fluoroperovskite. Nanocrystalline NaMgF3:Dy1%,Eu0.1% material was synthesized by hydrothermal technique. The structure and optical properties were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG), derivative thermogravimetry (DTG), radioluminescence (RL) and photoluminescence (PL) techniques. The bands on RL spectrum at 365, 488 and 477 nm might be attributed to Eu,2+ Eu3+ and Dy3+ ion emissions, respectively. The experimentally obtained TL glow curve was analyzed by the computerized glow curve deconvolution (CGCD) and various heating rate (VHR) methods and the order of kinetics (b), activation energy (E), and frequency factor (s) were determined for the appeared four peaks of the TL glow curve with 2°C /s heating rate. The energy bandgaps were calculated and the dependence of bandgap on composition was reported through the Density Functional Theory (DFT) computation.