Thermoluminescence Research Articles

Dating mortars and bricks of Santalla de Bóveda Monument (Lugo, NW Spain)

Santalla de Bóveda Monument (Lugo, NW Spain) is a small semi-buried building, under the Bóveda parish church, built in the 18th century, with an apsidal quadrangular floor plan, which was divided into three naves, a small vaulted apse and a rectangular floor plan vaulted, where paintings depicting birds and plant elements have been well preserved. The monument has aroused great interest since its discovery, but its chronology and functionality has always been the subject of controversy. Several hypotheses have suggested that the monument was built in the Roman period and some others around the 5h, 8th or 9th century AD. However, any direct evidence or absolute age has been provided until today. The stratigraphic analysis of the building suggests five constructive phases. Bricks and mortars of all phases were sampling to perform absolute dating techniques and to get a precise and accurate chronology. Radiocarbon dating of mortars and Optically Stimulated Luminescence (OSL) dating of bricks and mortars have been used to this purpose. A total of 34 samples were taken, being 20 used for luminescence (mortars and quartz aggregates) and 15 used for 14C ages (charcoal fragments of lime mortars). 5 brick samples were also dated by Thermoluminescence (TL). The obtained ages have allowed, for the first time, stablishing an accurate and precise chronology being the first phase assigned to the 4th Century AD. Alterations of the building and the vault paintings were performed in the early 7th century, while the construction of the second floor and occasional repairs were performed during the 10th-12th centuries.

Correlations between quartz OSL dose-response curve and TL glow curve characteristics, and their implications for equivalent dose estimation

Optically stimulated luminescence (OSL) dating of quartz using the single-aliquot regenerative-dose (SAR) procedure requires construction of dose-response curves (DRCs). The shapes of DRCs and their characteristic saturation doses (D0 values) are well-known to be highly variable between samples and among individual grains from the same sample, but the factors that control DRC characteristics are imperfectly understood. Here we report correlations between OSL DRC shapes and thermoluminescence (TL) glow curve characteristics for a sample of quartz from northern Australia. Individual grains were measured using the SAR procedure and one of two preheat temperatures (160 °C and 260 °C), and grouped according to similarities in their DRC shapes. Grains from each DRC group were then physically transferred onto a separate disc for TL measurement as a multi-grain aliquot. A strong correlation was observed between DRC group and laboratory-irradiated TL glow curve shapes, along with some differences between the two preheats. Irrespective of the selected preheat, earlier saturating DRC groups are associated with the most intense 110 °C TL signal, and the least intense 325 °C TL signal, which corresponds to the main OSL trap. Later saturating DRC groups generally show the opposite trend. There are also trends within other regions of the glow curve and DRC group, such as prominent TL responses at 140–160 °C, 220–240 °C and 390–410 °C. We assessed the effect on the accuracy of equivalent dose (De) estimation using an associated radiocarbon age as an independent cross-check of the OSL ages for the DRC groups. De over- and under-estimates were obtained for some DRC groups. Most notably, grains preheated to 160 °C displayed a pattern of De values which decreased with an increase in D0. We relate this to variable concentrations of charge at the ∼230 °C TL trap prior to regenerative dose OSL measurements. OSL ages for most DRC groups preheated to 260 °C are close to the radiocarbon age, as are those of later saturating DRC groups preheated to 160 °C; the latter DRC groups have the smallest TL signals at ∼230 °C relative to the TL peak at 325 °C. The results of this study suggest that correlations between single-grain De and D0 values can occur due to underlying differences in the TL characteristics of grains with different DRC shapes. In the absence of independent age control and prior to measuring multi-grain aliquots of quartz, we recommend that OSL dating practitioners screen their samples for any single-grain patterns of De as a function of DRC shape, to determine the optimal SAR measurement conditions and data-analysis procedures for De estimation.

Thermoluminescence dosimetry and microstructural characteristics of gamma-irradiated natural flake graphite

Thermoluminescence (TL) and microstructural analysis were conducted on natural flake graphite (NFG) to assess its suitability for radiotherapeutic x-ray dose measurements. The investigations encompassed the examination of TL glow curves, linearity, sensitivity, signal decay, and repeatability. NFG samples were exposed to 60Co gamma radiation doses ranging from 2 Gy to 20 Gy. The microstructure of the irradiated NFG was probed using a 532 nm laser Raman spectrometer. Promisingly, the NFG exhibited remarkable characteristics, including a moderately higher response to dose (R2 of about 96%), increased sensitivity at lower doses, and good repeatability (∼4%). Nevertheless, its fading rate reached about 80% after 14 days of irradiation. Additionally, the NFG intensity ratios of defect (D) to graphite (G), denoted as ID/IG, closely mirrored the oscillatory pattern observed in 50 μm thick graphite sheets and were approximately 1.6 times lower than those of similar graphite sheets with comparable carbon content (about 98% carbon). These findings suggest that NFG holds potential for the development of an affordable, non-hygroscopic, and tissue-equivalent TL dosimeter, with possible applications in the medical field.

Investigation of structural, photo and thermoluminescence properties of YAGG:Ce nanogarnet for medical dosimetry application

Cerium-doped yttrium aluminum gallium garnet (YAGG:Ce3+) nanophosphors were synthesized using the sol-gel method. Mixed garnet of Y2.97Al5-xGaxO12:Ce0.03 was prepared with varying gallium content: x = 0, 1, 2 and 3 Ga. The effect of gallium substitutions on the structural, photo and thermoluminescence properties of the prepared nanophosphors were studied by X-ray diffraction (XRD), photoluminescence (PL) and thermoluminescence (TL) techniques. XRD results indicated that the single and pure cubic crystal phase was formed for all nanophosphor samples regardless of the Ga content. The PL spectra of all the samples exhibited a green-yellow emission band centered at 522 nm attributed to the 5d → 4f transitions of Ce3+ ions. The TL glow curve spectra recorded after β-particle irradiation showed a strong dependence in terms of position, shape and intensity, of all temperature peaks with the Ga content. The highest TL sensitivity was observed for the sample prepared with x = 2 Ga, with main peak arising at low temperature (85 °C). The sample prepared at x = 1 Ga exhibited also high TL sensitivity with a simple glow curve spectrum showing a main peak at high temperature (∼158 °C). Thus, the linear dose response of this sample has been investigated in the wide dose range from 0.125 to 100 Gy in order to evaluate the potentiality of this material for radiation dosimetry applications.

Determination of the Kinetic Parameters of Thermoluminescent Glow Curves of Sintered Al2O3 Pills by Three Points Method

The three points analysis method, proposed by Rasheedy, was applied to separate a complex thermoluminescence (TL) glow curve into its individual components and determine, for each component, the kinetic parameters. These are the order of kinetics b, the activation energy E (eV), and the pre-exponential factor S'' (s^-1) associated with the TL glow peaks in sintered pure Al2O3 pills in response to gamma irradiation. The three points analysis method indicated that the glow curve of this material is the superposition of three general-order components, in which the recombination processes predominate over retrapping processes.

Kinetic analysis and dosimetric characteristics of the thermoluminescent glow curve of aquamarine (Be3Al2(SiO3)6:Fe)

Kinetic analysis of the thermoluminescent (TL) glow curve of aquamarine, a cyan variety of beryl (Be3Al2(SiO3)6), is reported. Samples were irradiated at room temperature using a90Sr/90Y β source at a rate of 0.10 Gy-1. Measurements made at 1 °C/s after irradiation from 1 to 100 Gy show a high intensity peak at 75 °C followed by three secondary peaks at 115, 189 and 302 °C respectively. The dose response of the high intensity peak (called the main peak) is linear within the first 20 Gy, but tends towards sub-linearity as the dose is close to 100 Gy. The signal decays with the time delay between irradiation and reading. It decays about 14% of its initial value, 600 s after irradiation. Reproducibility analysis shows that the material reproduces its response under identical experimental conditions with an uncertainty of 0.8% after 10 Gy beta dose irradiation. The kinetic analysis of the TL glow curve was carried out using the curve fitting method. The results show that the main peak follows first order kinetics, its activation energy is of the order of 1 eV and the frequency factor is between 1012 and 1014 s−1, while some secondary peaks follow general order kinetics.

Burn After Read: A Rewritable Multiplexing Optical Information Storage and Encryption Method

AbstractInformation storage and security are the building blocks of the information age. Optical information storage is a low‐cost, robust, and high‐capacity storage technique. Discovering new optical information storage media and techniques with beyond binary capacity and enhanced security is in demand. Here a beyond‐binary, “burn after read” and rewritable multiplexing optical information storage and encryption method is demonstrated via Ce:YAG trapping states. It is found that the thermo‐luminescence (TL) intensity of Ce:YAG trapping states is writing light power dependent, enabling multi‐gray‐level information storage and encoding.A new strategy to encode multiplexing information in a single pixel, increasing the storage capability is presented. Meanwhile, the burn after read feature protects the data from secondary leakage. This method has wide applications in data storage, anti‐counterfeiting, and encryption.

Thermoluminescence dosimetric characteristics and glow curve analysis of Eocene rock salt, the gray halite, mined from Bahadur Khel site, Pakistan

Thermoluminescence (TL) response of naturally occurring Eocene rock salt (Gray halite) is assessed for its potential use as a cost-effective phosphor for dosimetric applications. Natural deposits of the Eocene salt lie on the Himalayan foothills in Pakistan. The grayish color of the halite is due to the intermixing of black bitumen/shale. EDS and ICP-OES techniques are used for the analytical study of the sample. It confirms the presence of Ca, K, Mg, Sr, Zn SO4, Mn, Al, Si and Fe along with the main matrix-NaCl. The Eocene salt is sulfur (S) rich, and potassium (K) poor mineral as compared to the other regional halite. The XRD analysis shows that lattice structure of the halite is composed of two interpenetrating FCC-sublattices of Na and Cl. Cold pressed pellets weighing 40 mg are produced for dosimetric study of the material. Standard gamma source is used for pellet irradiaition. Three different samples of Eocene salt (i.e. rock salt, naturally precipitated salt and refined salt) are prepared. It is observed that, if the material is used as such in its natural form, the dosimetric peak of the glow curve occurs at higher temperature >260 °C. The raw form of rock salt is therefore pre-processed (refined) whereby the major glow peak has shifted onto the dosimetrically significant position at 230 °C. Because of the optimal shape of the glow curve, the refined salt sample is investigated in detail: TL glow curves are acquired from 50 °C to 300 °C, the phosphor reveals a composite glow curve where four peaks are observed at approximate positions of 110 °C (P1), 145 °C (P2), 180 °C (P3) & 230 °C (P4). TL response is studied in the range of 5 mGy to 2 Gy; where a linear/superalinear dose-response behavior is observed for the current material. The Minimum Detectable Dose Limit (MDDL) is measured from the linear region and found to be 0.37 mGy. The first readout results in very low residues <0.005 % and is sufficient to afresh the dosimeter for the next reading. A repeatability test is performed up to 20 identical cycles: the resultant COV, obtained for refined salt sample, is 2.3 % (and 1.5 % in 10 cycles). The irradiated pellets show about 20 % loss of the initial signal for one month fading study. Tm-Tstop method and CGCD techniques are used for kinetic analysis. Kinetic parameters (b, E and s) are estimated from multiple glow curves and found similarities in the results. The results of the preliminary investigations suggest that the pellet prepared from Eocene salt has a potential for use in TL dosimetry.

Photoluminescence and afterglow of Tb3+ doped BaAl2O4

Tb3+ doped BaAl2O4 phosphors (0–9.0 mol%) were prepared through sol–gel combustion method. The crystal structure, morphology, chemical composition, photoluminescence (PL), afterglow and thermoluminescence (TL) glow curve of Tb3+ doped BaAl2O4 were investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, PL spectroscopy, afterglow spectroscopy, and TL dosimetry. Characterizations of the PL and afterglow spectra indicate that both Tb3+ doping species and oxygen vacancies act as the luminescence center of PL whereas only Tb3+ dopant works as the luminescence center of afterglow for Tb3+ doped BaAl2O4. The green afterglow of Tb3+ doped BaAl2O4 lasts for about 214 min at the optimal doping concentration of about 1.0 mol%. The profile of TL glow curve of Tb3+ doped BaAl2O4 heavily depends on the doping concentration, and the evolution of the TL glow curve with doping concentration reveals that doping BaAl2O4 with Tb3+ can significantly modify the distribution of carrier traps in the phosphor. The effects of Tb3+ doping on the PL, afterglow, and TL glow curve of Tb3+ doped BaAl2O4 are discussed in terms of the creation, recombination, and neutralization of defects in BaAl2O4. This work proves that doing with Tb3+ species is a general and robust strategy for endowing BaAl2O4 with highly efficient green afterglow. This “defect engineering” approach enables ultra-long afterglow for Tb3+ doped BaAl2O4 when defect centers in the phosphors are optimized.

Thermoluminescence and optically stimulated luminescence of α-Al2O3 with different carbon concentrations

Carbon-doped α-Al2O3 (α-Al2O3:C) single crystals (nominal carbon concentrations with 500, 1000, 1500 and 2000 ppm) were grown by the vertical gradient freezing (VGF) method. Thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of as-grown α-Al2O3:C crystals were studied. F and F+ center absorption (except for the sample with 500-ppm carbon) at 205 and 256 nm was enhanced with increasing carbon concentration. The results show that TL and OSL intensities from α-Al2O3:C are strongly correlated with the ratio of absorption coefficients from the F-center to the F + -center. Both TL and OSL intensities of the sample doped with 1000 ppm reach maximum when the ratio of absorption coefficients from the F-center to F + -center is at its highest. The OSL response of the sample doped with 1000 ppm carbon is 3.43 times that of the sample doped with 500 ppm carbon and is 2.47 times higher than that of the TLD-500 K. The activation energies for samples with 500, 1000, 1500 and 2000 ppm carbon were calculated as 1.33 ± 0.11, 1.58 ± 0.02, 1.52 ± 0.02 and 1.52 ± 0.04 eV, respectively. The OSL intensities from α-Al2O3:C appear strongly correlated with the ratio of absorption coefficients F-center to F + -center. These attractive features may pave the way for the VGF method to improve the luminescence and dosimetry properties.

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.

Smart windows based on ultraviolet-B persistent luminescence phosphors for bacterial inhibition and food preservation

Herein, ultraviolet B (UVB) persistent luminescence phosphors containing SrAl12O19: Ce3+, Sc3+ nanoparticles were reported. Thermoluminescence (TL) spectrum analysis reveals that the shallow trap induced by Sc3+ co-doping plays an important role in photoluminescence persistent luminescence (PersL) development, while the deep trap dominates the generation of optical stimulated luminescence (OSL). Owing the appearance of deep trap, the OSL is observed under light (700 nm - 900 nm) excitation. UVB luminescence exerts good bactericidal effects on pathogenic bacteria involved in the process of food spoilage. Thus, the smart window with SrAl12O19: Ce3+, Sc3+/PDMS produces UVB PersL to efficiently inactivate Escherichia coli and Staphylococcus aureus. In addition, the presence of the smart window delays the critical point of pork decay, and greatly reduces the time of pork spoilage. It maximizes the convenience of eradicating bacteria and preserving food, thus offering a fresh perspective on the use of UV light for food sterilization and preservation.

Optically-stimulated luminescence and thermoluminescence properties of RbI:Eu single crystals

Optically-stimulated luminescence (OSL) and thermoluminescence (TL) properties of RbI:Eu single crystals synthesized by the vertical Bridgman-Stockberger method were evaluated. OSL peak at 430 nm due to 4f65d1-4f7 transition of Eu2+ was observed under stimulation at 750 nm. The 0.5% Eu-doped sample exhibited the highest OSL intensity among all the sample, and the detection limit was 1 mGy. TL glow peaks at ∼100 and ∼200 °C were observed and were ascribed to Fz-center (F-center near Eu2+-cation vacancy dipole) and F-center, respectively. The 0.5% Eu-doped sample showed the highest TL intensity among all the sample, and the detection limit was 0.01 mGy.

Evaluation of TL and OSL signals of MgB4O7:Tm,Li prepared by the solution combustion method

Magnesium tetraborate (MgB4O7) doped with rare-earth elements is recognized for its suitability in thermoluminescence (TL) dosimetry due to its low effective atomic number (Zeff = 8.4) and the potential applications in neutron dosimetry. The study investigates the luminescent (TL and OSL) properties of MgB4O7 doped with thulium (Tm3+) and lithium (Li+). Samples were synthesized using the solution combustion method and TL and OSL responses were evaluated using a spectrometer and an automated OSL/TL reader. The emission lines of Tm3+ are consistent with previous literature, with Li+ enhancing TL and OSL responses. TL emission spectra unveil distinct bands corresponding to [Tm3+]* transitions. The electron paramagnetic resonance (EPR) spectroscopy analysis carried out in unirradiated, irradiated and annealed samples.The results show that the signals corresponding to BO32− and O2− are seen upon irradiation and disappear after annealing at 200 °C, indicating the participation of these centers in the TL process. The results show that the TL response of MgB4O7:Tm,Li is much more sensitive to gamma radiation than MgB4O7:Tm, with a minimum detectable value of 0.084 mGy and a linear response with dose for the range studied, from 0 to 500 mGy, with R2 of 0.998.

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.

Neutron-induced thermoluminescence of Dy3+-doped B2O3–Na2O–CaO–P2O5 glasses

Thermoluminescence (TL) materials based on Dy3+-doped B2O3–Na2O–CaO–P2O5 glasses have been developed for neutron detection. After X-ray irradiation, the TL glow peaks were observed at 360 K, and the TL intensities of the 10B- and 11B-enriched samples were similar. After neutron irradiation, a significant difference in the TL intensities was observed between the 10B- and 11B-enriched samples, which indicates that γ-rays and high-energy particles in the 10B (n, α)7Li reaction efficiently induced TL. The TL intensities derived from the 10B (n, α)7Li reaction linearly increased with neutron fluence of 106–1011 neutrons cm−2. Therefore, TL glass materials were successfully developed for neutron detection.

A promising route for developing green phosphor with mechanoluminescence and long persistent luminescence in Sr2Ga2GeO7: Tb3+

Mechanoluminescence (ML) materials featuring photon emission under mechanical stimulation have attracted the attention of scientists doing researches on structure monitoring, stress sensing, anti-counterfeiting and imaging. In this study, a novel series of ML green phosphors Sr2-xGa2GeO7: xTb3+ (0 ≤ x ≤ 0.05) have been synthesized by a high-temperature solid-state method for the first time. Their crystal structure, optical properties and attenuation profiles have been investigated. X-ray diffraction (XRD) analysis reveals that the sample is tetragonal with a space group of P4‾ 21m, and Tb3+ partially replaces the lattice position of Sr2+ in the Sr2Ga2GeO7 crystals. The green ML emission mechanism is attributable to the typical 5D4 → 7F5 transition of Tb3+ ions, similar to persistent luminescence (LPL) and the photoluminescence (PL). To better understand the mechanism of potential LPL and ML in this system, the trap regulation is comprehensively investigated by a series of thermoluminescence (TL) measurements.

Investigations of swift heavy ion induced thermoluminescence effect, trapping parameter analysis, and density functional theory of MgB4O7: Eu phosphor

The present work reports swift heavy ion (SHI) induced thermoluminescence (TL) dosimetric properties and density functional theory (DFT) studies of Eu doped MgB4O7 phosphor. Comparative investigations of structural, and luminescent properties of MgB4O7:Eu phosphor upon irradiation by 100 MeV Ag7+ and Ni7+ ion beams at the varied fluence range from 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2 are presented systematically. Eu doped MgB4O7 phosphor is prepared by facile hydrothermal method. X-ray diffraction pattern of the material reveals its orthorhombic structure with crystallite size of ∼30 nm. Fourier transform infrared spectroscopy (FTIR) studies demonstrate loss of crystallinity of material after the SHI irradiations. Correlation of stopping powers and projectile range calculations is performed using SRIM software. The investigated photoluminescence properties show emission bands located in the orange-red region with prominent peaks centered at ∼593 nm and ∼625 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions of Eu3+ion. The influence of ion beam fluence on the photoluminescence properties has been explored. Variation in the intensity of the PL peaks without any shift in the peak positions is observed at different ion fluence. The TL glow curve of phosphor exhibits two major dosimetric peaks (a) at 185 °C and 275 °C and (b) at 172 °C and 273 °C upon Ag7+ and Ni7+ ion beam irradiation respectively. The phosphor shows fairly good linear dose response in the range of 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2. Fading measurements reveal 10% and 12% fading for the irradiation of Ag7+ and Ni7+ ions respectively in two months. Trapping parameter calculations of SHI irradiated phosphors are carried out via various TL glow curve analysis methods such as, peak shape method, whole glow peak method, and glow curve deconvolution method. Efficient thermoluminescence properties of MgB4O7:Eu make it a potential phosphor material and promise to provide avenue into swift heavy ion dosimetry applications. DFT computational studies performed to obtain the electronic structure of Eu doped MgB4O7 phosphor support the experimental results of crystal structure, symmetry and electronic structure studies.

Dosimetric properties of Cr–La, Cr–Cu, and Cu–La ions codoped Ca9 Al (PO4)7 nanostructure

In the present work, Cr–La, Cr–Cu, and Cu–La ions codoped Ca9Al (PO4)7 nanostructures (symbolized as Cr–La, Cr–Cu, and Cu–La) were prepared using the sol-gel method for their dosimetric properties. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results reflected the existence of the nanoparticle structure. This confirmed the successful sol-gel preparation method used. The surface morphological properties of the prepared samples were scrutinized by scanning electron microscopy (SEM). The presence and distribution of the constituent elements of the samples were determined using energy-dispersive X-ray (EDX) spectroscopy. The thermoluminescence (TL) sensitivity enhancement and homogenous properties of the prepared samples were assessed using a γ-radiation dose of 5 Gy. TL sensitivity of the Cr–Cu sample was found to be optimum. The relative standard deviations (RSD) of the homogenous study were found to be 6.5, 5.7, and 3.9% for Cr–La, Cr–Cu, and Cu–La, respectively, which were acceptable according to the ISO requirements (<10%). The dose-linearity response was investigated in 0.5 up to 20 Gy γ-dose ranges. The sample Cr–Cu had a good dose-linearity of up to 20 Gy while the others (Cr–La and Cu–La samples) had a dose-linearity of up to 13 Gy. The threshold doses (MDD) of the Cr–La, Cr–Cu, and Cu–La samples were computed and found to be approximately 110, 32, and 134 μGy, respectively. The photon attenuation parameters of the prepared samples were computed using the Phy-X PSD program, and the acquired data showed that the Ca9Al (PO4)7 composition had bone-equivalent material characteristics. Results of the dosimetric properties of Cr–La, Cr–Cu, and Cu–La co-doped Ca9Al (PO4)7 samples suggested that these compositions had potentially excellent TL characteristics to be used in various dosimetric applications across a broad range of gamma doses.