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Phototransferred thermoluminescence (PTTL) induced from natural calcite using 470, 525, and 405 nm illumination is reported. We consider the measurement and analysis of time-response profiles, the dependence of PTTL intensity on the sample temperature during illumination to induce phototransfer, the role of deep electron traps, and discuss mechanisms for phototransfer in calcite. The conventional TL glow curve is a complex collection of closely overlapping glow peaks, but there are three stand-out ones near 90, 210, and 330 °C, denoted as I–III. These are reproduced under phototransfer. The dependence of PTTL intensity on illumination can be properly described by systems of acceptors and donors, where the number of the latter depends on the preheating temperature. The systems have been analyzed by phenomenological and kinetics models. The intensity of the PTTL is influenced by the illumination temperature, and the attendant thermal assistance and thermal quenching have been quantified. Electronic processes relevant to the PTTL of calcite are thought to involve the relaxation of (CO3)2− and Mn2+ ions. An anomalous increase in PTTL induced from deep electron traps has been deduced to be a possible result of quantum tunneling of charge between (CO3)3− stabilized close to Mn3+ cations. [ABSTRACT FROM AUTHOR]

The x-ray spectrum of a flash radiography source based on wire-shorted rod-pinch diode (RPD) is measured by an absorption spectrometer and calculated by the Geant4 Monte-Carlo code. The RPD is driven by a two-stage linear transformer driver (charging voltage ±45 kV per stage), which delivers ∼300 kA current within ∼200 ns on a short-circuit inductive load (∼30 nH). The spectrometer consists of LiF thermoluminescence dosimeters and metal filters of different materials and thicknesses, and the spectrum is reconstructed based on the Geant4 simulated dosimeter responses to various photon energies through different filters. The measured spectrum reaches an endpoint photon energy of ∼130 keV. The radiation characteristics of the RPD in the experiment are also modeled in Geant4 using measured voltage and current waveforms, and the results show an overestimation in photon number and endpoint energy (∼147 keV) compared to the measured spectrum, which indicates that during the bremsstrahlung process, the effective electron current is ∼27% of the total current, and the effective voltage is ∼12% lower than the directly reconstructed resistive voltage. A rough agreement is found between the spectra results and the non-relativistic Bethe–Heitler model with Sommerfeld correction; therefore, the analytic result can serve as an initial guess for spectrum reconstruction methods such as the perturbation method. [ABSTRACT FROM AUTHOR]

This study investigates the luminescent properties and dosimetric potential of YCa 4 O(BO 3) 3 :0.5%Sm3+ phosphor synthesized via the combustion method. Dose-response investigations unveil a noteworthy linear increment in thermoluminescence (TL) intensity, emphasizing a remarkable linearity spanning a broad dose range from 0.1 to 300 Gy. Unusual heating rate effects are explored, revealing a shift in TL glow curve peak temperature (i.e 200 °C) towards higher temperatures with increasing heating rate. Speculative models, including Kinetic Trapping Effect, Thermal Quenching Compensation, and Defect Activation Energy Changes, are proposed. The study employs the T max - T stop method to identify characterize glow curve peaks, and the Initial Rise method for the low-temperature segment analysis, revealing seven distinct trap levels at various depths within the bandgap. Glow curve deconvolution using the Complex Glow Curve Deconvolution (CGCD) method delineates a multi-peak structure, offering valuable insights into luminescent mechanisms. The model exhibits a Figure of Merit (FOM) of 1.71%, within an acceptable range, affirming its reliability. However, interpretation of the activation energy and frequency factor values suggests intricate site processes, necessitating a nuanced analysis to understand the material's luminescent characteristics. The YCa 4 O(BO 3) 3 :0.5%Sm3+ phosphor demonstrates promising characteristics for precise dosimetry, with linear dose response, absence of saturation effects, and intriguing heating rate behavior. [ABSTRACT FROM AUTHOR]

Scintillators with high light yield, spatial resolution, and detection sensitivity are desirable for X‐ray imaging. Howerer, it remains challenging to improve the light yield and radiation detection capability of alkali metal rare‐earth fluoride (ALnF4). Herein, a type of Cu2+ ion heterovalent co‐doped LiLuF4:Tb,Cu microcrystalline scintillation material with high light yield, persistent, and thermostimulated luminescence is obtained by defect engineering. The heterovalent codoping strategy not only increases the radioluminescence (RL) intensity, but also introduces more carrier traps in the material to enhance the long‐afterglow and thermoluminescence intensity of LiLuF4:Tb microcrystals. After doping of 3 mol% Cu2+ ions, the RL efficiency is increased by 88.61%, and the X‐ray detection limit of LiLuF4:Tb,Cu reaches 2.7928 nGy·s‒1. This detectivity is considerably lower than the medical imaging requirements (5.5 µGy·s‒1). Furthermore, a large‐area flexible scintillation film of dimensions 30 × 30 cm2 is prepared to achieve high spatial resolution X‐ray imaging of 22 LP mm−1@MTF(modulation transfer function) = 0.2. Besides, this flexible film enables X‐ray imaging of curved objects and stores optical information for >48 h. This work provides a paradigm for improving the RL intensity and X‐ray detection sensitivity of alkali rare‐earth fluorides by crystal defect engineering, and enriches X‐ray high resolution extended imaging applications. [ABSTRACT FROM AUTHOR]

ZrO2 samples were obtained using three different synthesis methods (Calcination, Co-precipitation and Hydrothermal). The samples were characterized to analyze the effect of the crystalline phase on their thermoluminescent (TL) and photoluminescent (PL) responses. The ZrO2 phase was analyzed by X-Ray diffraction (XRD) and Raman. Nanoparticle size distribution was obtained by scanning electron microscopy (SEM). For optical analysis, characterizations included absorbance measurements, where samples exhibited modifications in color centers, PL emission and experimental fluorescence lifetime decay (τexp) measurements. Additionally, their TL response was studied under UV (245nm and 385nm), and 6MV photon energy from LINAC excitation. The obtained results show the improvement of TL and PL properties due to ZrO2 phase while an amorphous ZrO2 synthesized by hydrothermal method is an excellent prospect to be used as TL material and it may be a promising scintillator material at 254nm. [ABSTRACT FROM AUTHOR]

Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce3+-doped Tb3Al5−xScxO12 crystals (where x ranges from 0.5 to 3.0), revealing a novel approach to control luminescence and photoconversion through atomic size mismatch engineering. Raman spectroscopy confirmed the coexistence of garnet and perovskite phases, with Sc substitution significantly influencing the garnet lattice and induced A1g mode softening up to Sc concentration x = 2.0. The Sc atoms controlled sub-eutectic inclusion formation, creating efficient light scattering centers and unveiling a compositional threshold for octahedral site saturation. This modulation enabled the control of energy transfer dynamics between Ce3+ and Tb3+ ions, enhancing luminescence and mitigating quenching. The Sc admixing process regulated luminous efficacy (LE), color rendering index (CRI), and correlated color temperature (CCT), with adjustments in CRI from 68 to 84 and CCT from 3545 K to 12,958 K. The Ce3+-doped Tb3Al5−xScxO12 crystal (where x = 2.0) achieved the highest LE of 114.6 lm/W and emitted light at a CCT of 4942 K, similar to daylight white. This approach enables the design and development of functional materials with tailored optical properties applicable to lighting technology, persistent phosphors, scintillators, and storage phosphors. [ABSTRACT FROM AUTHOR]

In this paper, X‐ray‐activated super long persistent ultraviolet A luminescence from Ca3(PO4)2: Ce3+ has been observed. The crystal structure analysis has shown that the as‐prepared samples are pure β‐Ca3(PO4)2 phases with rhombohedral structure and R3c space group. The photoluminescent spectra of the samples all consist of a broad band in 340–400 nm UVA1 region, which is assigned to the 5d1–4f1 electronic transition of Ce3+ ions. More important, under the 3 min X‐ray irradiation, Ca3(PO4)2: Ce3+ show super long persistent luminescence in the UVA1 region, which can persist for more than 16 h. And its afterglow intensity after 16 h decay is still 4.10 times stronger of the back ground intensity. Furthermore, only 10 s X‐ray irradiation can induce excellent long persistent UVA luminescence of Ca3(PO4)2: 0.08Ce3+, which can persist for more than 5 h and afterglow emission intensity is about 3.03 times of the background intensity. The trap analysis has confirmed that the different X‐ray irradiation time do not create new traps and there is the same trap with 0.75 eV trap depth existing even under the extremely low X‐ray dose (10 s X‐ray irradiation). Furthermore, under 10 s X‐ray irradiation, the thermoluminescence (TL) intensity of Ca3(PO4)2: 0.08Ce3+ still reaches 0.32 times of the initial TL intensity even after 120 min, which thus leads to the super long persistent luminescence. Thus, the large amounts of trapped electrons induced by the high energy X‐ray irradiation are the principal cause for super long persistent UVA luminescence of Ca3(PO4)2: Ce3+. [ABSTRACT FROM AUTHOR]

The purpose of this research was to develop glasses that are thermally reflective, radiation-resistant, and mechanically robust. We have synthesized the La(20-x)Pb10B70:Eux series of glasses in this regard. Then, characterization, radiation shielding, structural analysis (Raman, FT-IR, DTA, SEM, XRD, and EDX), dielectrics, thermoluminescence are planned. The XRD and SEM analyses of the test samples reveal a vitreous appearance. The chemical constituents are identified by the EDX analysis in terms of their percentage of atomic weight. The density (2.592 g/cm3) and molar volume (45.44 cm3 mol−1) of the fabricated glass were evaluated as physical properties. The glass transition temperature (approximately 273 °C) and thermal stabilities (0.656 percent) of glasses are determined to be solely dependent on Eu3+ ions, according to DTA investigations. FT-IR and Raman analyses were employed to determine the various structural vibrations of the sample glass. By employing the ultrasonic velocities of the test glasses, an assessment was conducted on the micro-hardness of the glass (5.01 GPa). The shielding characteristics of radiation, such as RPE (31.6 percent) and MAC (16.9 cm2/g), indicate that the shielding behavior is solely the result of the Eu3+ ions. It has been observed that TL properties are examined at gamma irradiation intensities ranging from 5 to 25 kGy. An evaluation was conducted on the frequency factor (3.225 × 1021 S−1) and A.E. (1.785 eV) of glasses. The findings indicate that the TL characteristics of glasses are solely influenced by the Eu3+ ions. Additionally, the investigation of the dielectric properties of glasses was ascertained. The analysis focused on the dielectric constant (8.891), dielectric loss (0.026), ac conductivity (0.735 × 10–8 Ω−1 cm−1), and A.E. (1.051 eV) values of the fabricated glass. The findings suggest that the dielectric properties of glasses are entirely determined by the presence of Eu3+ ions. Overall the LBPE-1.5 glass found to be best in the structural, mechanical, optical, dielectric, radiation shielding and thermoluminescence properties. [ABSTRACT FROM AUTHOR]

This study analyzes thermoluminescence (TL) glow curves simulated in general order kinetics (GOK), one trap one recombination center (OTOR), and non‐interactive multi‐trap system (NMTS) models using various heating rates (VHR) method in linear heating scheme to extract the activation energy. A theoretical analysis to determine activation energy from TL curves using OTOR and NMTS models in an iterative manner, where the TL intensity is determined by using the Lambert‐W function, is proposed with its limitations. It is established that the activation energies in OTOR and NMTS models consist of the relevant GOK term and a respective correction term. Systematic analysis is carried out to study the improvement of the accuracy of activation energy derived from OTOR and NMTS model TL curves over the GOK model calculation. A quantitative analysis of the quasi‐equilibrium (QE) approximations is carried out for choosing appropriate system parameters. The validity of QE conditions are determined by studying variations of full width at half maximum as well as area under the curve as a function of heating rate. The present method is applied on some experimental data to estimate activation energies. This investigation reveals that the activation energy derived in VHR method has negligible dependence on the underlying theoretical models, i.e., the activation energy derived from GOK model calculation is significantly accurate for experimental scenario. [ABSTRACT FROM AUTHOR]

To fully harness the potential of molecular machines, it is crucial to develop methods by which to exert control over their speed of motion through the application of external stimuli. A conformationally strained macrocyclic fluorescent rotamer, CarROT, displays a reproducible and linear fluorescence decrease towards temperature over the physiological temperature range. Through the external addition of anions, cations or through deprotonation, the compound can access four discreet rotational speeds via supramolecular interactions (very slow, slow, fast and very fast) which in turn stop, reduce or enhance the thermoluminescent properties due to increasing or decreasing non‐radiative decay processes, thereby providing a means to externally control the temperature sensitivity of the system. Through comparison with analogues with a higher degree of conformational freedom, the high thermosensitivity of CarROT over the physiological temperature range was determined to be due to conformational strain, which causes a high energy barrier to rotation over this range. Analogues with a higher degree of conformational freedom display lower sensitivities towards temperature over the same temperature range. This study provides an example of an information rich small molecule, in which programable rotational speed states can be observed with facile read‐out. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) is a fascinating phenomenon with diverse applications in pressure sensing, damage detection, and stress distribution visualization. However, most ML materials exhibit instantaneous photon emission that requires real‐time recording with a photodetector, and thereby circumscribing their applicability predominantly to real‐time stress‐sensing scenarios. In this work, a novel method is introduced for non‐real‐time stress sensing utilizing Li0.1Na0.9NbO3:Pr3+ phosphor, which allows for the retrieval of pressure location and intensity even 20 days after the event. The influence of heat and pressure on the trap depth distribution is analyzed using thermoluminescence (TL) and ML measurements, and it is proved that both heat and pressure release the captured electrons in the same traps. Leveraging the intricate competition between mechanical and thermal detrapping processes, stress information can be accessed through TL imaging. Furthermore, an algorithm is proposed based on this phenomenon to authenticate the stress information. This research not only advances the fundamental understanding of ML phenomena but also introduces a novel approach for applications such as mechano‐history indicators, security papers, and advanced data storage systems. [ABSTRACT FROM AUTHOR]

When KCl:Eu2+ single crystals were exposed to X-ray and were plastically deformed by compression at 50 µm min−1, the peak appears around 330 K on the thermoluminescence (TL) glow curve under the influence of the compressive load below 200 N. The peak is termed 330 K peak here. Its intensity becomes slightly large with the compressive load and also depends on the quenching temperature above about 473 K for the preparation of sample. Furthermore, the 330 K peak disappears on the TL glow curve by the heat treatment: annealing at 953 K for 16 h, followed by gradually cooling to room temperature within 24 h. The variations in the 330 K peak height are related to the density of dislocations in the sample. On the absorption spectrum for the crystal, the peak height at the wavelength of 560 nm decreases by the heat treatment. This result is supposed to be caused by the phenomenon that dislocation density is reduced and some colour centres on the 330 K peak etc. are removed in the annealing process of the crystal. [ABSTRACT FROM AUTHOR]

The dependence of thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of LiMgPO4:Tb,Sm,B samples prepared by the high-temperature solid-state method on maximum heating temperatures was investigated for the first time. The TL glow curves showed the ratio of peak 3 to peak 2 increased with the increase of maximum heating temperature. The influence of OSL on maximum heating temperatures showed that the sensitivity of OSL reached the maximum at the maximum heating temperature of 1000°C, which is 11.6 times higher than that of 800 °C. The relative standard deviation of the repeatability is less than 1.5% regardless of the maximum heating temperature. The minimum measurable dose (MMD) could be significantly improved by optimizing OSL parameters, such as maximum heating temperature and readout time. The MMD as low as 0.31 µGy has been achieved. The residual OSL is up to 92.3% after irradiation for 24 h. LiMgPO4:Tb,Sm,B is highly sensitive to the maximum heating temperature. Considering fast decay time, high OSL sensitivity, good repeatability, low MMD and little fading, it is recommended that the maximum heating temperature of LiMgPO4:Tb,Sm,B is 1000°C. LiMgPO4:Tb,Sm,B has great potential for daily personal and environmental cumulative dose monitoring. [ABSTRACT FROM AUTHOR]

This research investigates the structural and thermoluminescence (TL) properties of Sr2+-doped Ca 5 (PO 4) 3 OH (HAp) phosphors. X-ray diffraction (XRD) analysis confirms that HAp has a hexagonal structure with a P63/m space group. The TL behaviour of HAp:Sr2+ phosphors is examined under beta irradiation in the temperature range of 25–500 °C. The study reveals three TL glow peaks at temperatures of 75, 212, and 296 °C. Investigation of TL responses across heating rates (HR) ranging from 0.1 to 5 °C/s shows that higher HRs result in increased maximum TL peak temperatures and reduced TL intensities. This trend suggests an augmented contribution from non-radiative transitions as the heating rate increases. Importantly, no evidence of thermal quenching is found in the HAp samples. Two different methods, Hoogenstraaten's and Booth-Bohun-Porfianovitch, yield consistent activation energy values of 0.50, 1.22, 1.67 eV, and 0.48, 1.19, 1.63 eV, respectively. Reusability assessments indicate a standard deviation of less than 5 %, confirming the reliability of the materials. T m − T stop analysis reveals a continuous distribution of trap levels. TL properties in HAp samples have been comprehensively characterized, contributing not only to enhancing our understanding of their behaviour, but also highlighting their potential applications in various areas. The findings of this study have provided valuable insight into the development of efficient catalysts that are suitable for a variety of applications. [ABSTRACT FROM AUTHOR]

The Li 9 Mg 3 [PO 4 ] 4 F 3 fluorophosphate, which is considered as a promising dosimetric material, was prepared by the conventional solid-phase and microwave-assisted methods. The dosimetric properties of the obtained materials were examined and compared. The results revealed that the microwave-assisted synthesis leads to a fourfold enhancement of the thermoluminescence. Analysis of structural data showed that prolonged contact with the atmosphere can cause the loss of fluorine, resulting in the deterioration of material properties. This effect is also evidenced by the increase in the ESR signal, which is associated with a larger number of antisite defects, for the fluorophosphate obtained by the microwave-assisted method. The additional synthesis of Li 9 Mg 3 [PO 4 ] 4 F 3 with an excess of LiF allowed us to suppress the fluorine losses, thereby leading to an additional manifold increase of the thermoluminescence. [ABSTRACT FROM AUTHOR]

Here, we have developed a novel ultra long ultraviolet-A afterglow material CaMgGeO 4 : Bi3+, which shows more than 24 h UVA afterglow emission peaked at 346 nm. The crystal structure shows that the prepared sample is a pure phase with an orthogonal system of Pmnb space group. The composition of valence band and conduction band was analyzed by the density of states, which reveals that the bandgap of the CaMgGeO 4 matrix is 3.69 eV. The photoluminescence spectrum of the sample consists of a broadband in the 320–400 nm UVA region, which belongs to the 3P 1 → 1S 0 electron transition of Bi3+. More importantly, under the excitation of ultraviolet lamp for 3 min, CaMgGeO 4 : Bi3+ exhibited an UVA ultra long persistent luminescence (LPL) with a duration of more than 24 h, which afterglow emission intensity still reaches 1500 cps and is about 6 times of the background intensity. In addition, the UVA emission of CaMgGeO 4 : Bi3+ after 13 h day can be repeatedly by short periods of low-energy light sources stimulation. The thermoluminescence analysis indicates that the presence of shallow and deep traps is responsible for excellent UVA-LPL and photo-stimulate luminescence (PSL). The excellent LPL and PSL properties can prompt CaMgGeO4: Bi3+ phosphor to be widely used in the field of photodynamic therapy. [ABSTRACT FROM AUTHOR]

Thermoluminescence and its kinetic analysis, and defects in SrAl 2 O 4 have been investigated. SrAl 2 O 4 was synthesized by the solution combustion method. Rietveld refined X-ray diffraction pattern of SrAl 2 O 4 reveals a monoclinic phase with space group P 2 1. The average crystallite size and stain are 48 nm and 0.04 %, respectively. The chemical composition of the sample is examined by the X-ray fluorescence technique. The micrographs of SrAl 2 O 4 revealed that the particles are agglomerated with a porous nature. Defect centers involved in TL process is identified by EPR studies. TL of beta irradiated (40 Gy) SrAl 2 O 4 displays three peaks and these peaks are reproducible at 104.4 ± 1.6 οC, 133.5 ± 1.0 οC and 260.5 ± 1.5 οC. In view of the TL curve being complex, the peaks analyzed using thermal cleaning and T m -T stop methods revealed that there are four peaks associated with the glow curve. The kinetic parameters are calculated using different techniques. TL peaks observed at 134 and 260 οC follow first order kinetics that is confirmed from qualitative and quantitative results. TL peak at 104 οC completely fades within 108000 s (30 h) whereas the intensity of 134 οC and 206 οC peak drops down to 63 % and 2 % of its initial value within 108000 s of irradiation. TL main peaks 1 and 2 are subject to thermal quenching, the activation is found to be 0.54 ± 0.09 and 0.77 ± 0.03 eV, respectively. This work elucidates the dosimetric features, kinetic analysis, and defects in undoped SrAl 2 O 4. [ABSTRACT FROM AUTHOR]

A series of Tb3+ substituted layered perovskite Sr(La 1- x Tb x)AlO 4 (x = 0–1) was synthesized via solid-state reaction. The influence of Tb3+ on the phase, structure, photoluminescence, and long afterglow properties of the SrLaAlO 4 product was investigated. The fully substituted product SrTbAlO 4 was found to be isostructural with its SrLaAlO 4 counterpart, and the crystal structure parameters were first reported in this work. Photoluminescence investigation found that benefiting from the unique layered crystal structure, the activator Tb3+ was well separated and the optimal doping concentration was found to be as high as 20 at%. Except for photoluminescence, the products simultaneously show long afterglow properties due to disorder cations distribution in the local structure and thus induced defect condition. When the UV light source is turned off, the afterglow luminescence of SrLaAlO 4 : 0.03 Tb3+ can last over 1 h. The trap distribution of SrLaAlO 4 : Tb3+ was analyzed in detail by thermoluminescence. The trap depth is calculated to be around 0.7–0.81 eV, the value of which highly coincides with the ideal energy level for trapping and releasing electrons at room temperature. On the basis of the experimental results, the mechanism of long afterglow luminescence of SrLaAlO 4 : Tb3+ is elaborated and discussed. [ABSTRACT FROM AUTHOR]

Establishing the absolute age of palaeoearthquakes is of great significance for the assessment of the seismicity and seismic hazards of a region. As such, several different geochronological techniques to date earthquake-related material have been developed to provide answers on the time of past earthquakes. The present study is part of a wider palaeoseismic research project conducted in the Nojima Fault Zone (NFZ), where the 1995 Mw 6.9 Kobe (Japan) earthquake was triggered, to assess the suitability of the isothermal thermoluminescence (ITL) dating technique on fine-grained quartz and medium-grained feldspar and to provide a sequence of ages for fault-rock samples separated from a drilled core that was retrieved from a depth of ~506 m. Our analysis reveals that ITL can produce consistent dating results and can be considered a reliable luminescence technique for the absolute dating of fault-gouge material. The produced ITL ages signified the existence of repeated seismic events within the NFZ that took place through the late Pleistocene period, with gouge ages spanning from 78.6 ± 4.2 to 13.4 ± 1.4 ka; however, overestimation of the produced ITL dating results may be apparent. Nonetheless, even though some degree of overestimation is considered, ITL dating results denote the oldest possible age boundary of formation (or luminescence signal resetting) of the collected fault-gouge layers. [ABSTRACT FROM AUTHOR]

Various yellowish-green persistent phosphors of Y2.95−x−yLuxGdyAl5−zGazO12:0.05Ce3+ (x = 0–1, y = 0–1, z = 1–4) were successfully synthesized by the one-step high-temperature solid-state reaction method in air. The effects of simultaneous doping of Lu3+, Gd3+ and Ga3+ on the luminescence properties of the phosphors were investigated in detail for the first time. Herein, the microstructure, morphology, afterglow performance, luminescence properties, thermoluminescence, thermal quenching and flicker index of the efficient blue-light-activated Y2.95−x−yLuxGdyAl5−zGazO12:0.05Ce3+ phosphors were tested. The τ90 and τ80 values of Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ are 10.8 ms and 33.2 ms, respectively. These parameters are important in terms of effectiveness in reducing flicker in alternating current (AC) LEDs. Compared with the conventional Y3Al2Ga3O12:Ce3+ phosphor, the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor has a better luminescence performance, stronger afterglow performance, and lower flicker index. The quantum yield of the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor was 86.42% and the luminous efficiency of the LED devices prepared with it reached 92.12 lm W−1 when operated at 100 mA. Integrating sphere and spectroradiometer tests as well as CIE chromaticity diagrams indicate that the AC-WLEDs assembled by mixing the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor and a commercial red phosphor in an appropriate ratio could obtain ideal white light with a high color-rendering index (87.9) and the flickering index was successfully reduced from 100% to 61.4%. [ABSTRACT FROM AUTHOR]

Samples of ZrO2 ceramics with different concentrations of impurity titanium ions were synthesized by mixing zirconium and titanium oxide powders in different mass ratios. The X-ray diffraction analysis was used to determine the phase composition, lattice parameters, and crystallite size of the ceramics with varying dopant concentrations. Upon irradiation of the samples with 220 MeV Xe ions to a fluence of 1010 ions/cm2, a decrease in the intensity of the pulsed cathodoluminescence band at 2.5 eV was observed. Additionally, ion irradiation resulted in the emergence of a new thermoluminescence peak at 450–650 K attributed to radiation-induced traps of charge carriers. Further analysis revealed that the thermoluminescence curves of samples irradiated with electrons and ions comprise a superposition of several elementary peaks. Notably, a complex non-monotonic dependence of cathodo- and thermoluminescence intensity on titanium concentration was observed, suggesting the influence of concentration quenching and the presence of tunneling transitions. [ABSTRACT FROM AUTHOR]

Mechanoluminescent materials, which are capable of converting some ignored mechanical stimuli like friction, pressure, and distortion into useful photons, are gathering increasing attention nowadays, especially considering that a new round of energy crisis is sweeping across the globe. However, the wavelength of mechanoluminescence (ML) reported so far overlaps seriously with the solar spectrum, limiting the practical applications of mechanoluminescent materials to some extent. Here, we report the ultraviolet-C (UVC) ML from NaYF4:Pr3+ with the central wavelength at ∼250 nm, which is one of the shortest wavelengths for ML and is ascribed to the 1S0 → 3F4 transition of Pr3+. After being charged by x rays, NaYF4:Pr3+ is able to emit ML under the stimulation of external stress. The presence of UVC ML has been confirmed by both a spectrometer and a solar-blind camera. We confirm that the UVC ML belongs to the trap-controlled ML via thermoluminescence and related trap-filling-emptying measurements. With the aid of the density functional theory, we discuss the possible mechanism of the UVC ML from NaYF4:Pr3+. [ABSTRACT FROM AUTHOR]

Silica fibre thermoluminescence (TL) dosimeters have demonstrated versatility in medical and industrial, offering high spatial resolution, sensitivity, water resistance, and insensitivity to electromagnetic fields. A systematic review focusing on the medical applications of silica fibre TLDs is conducted, highlighting the potential of these materials in medical radiation dosimetry. Despite some limitations, such as non-linearity at low energies and relatively high signal fading, silica fibre TL dosimeters have shown excellent TL performance. However, their application in clinical practice is yet to be established since the TL responses for a wide range of doses and energies are not accurately certified yet. [ABSTRACT FROM AUTHOR]

While several devices can monitor temperature, measuring non-volatile thermal history is far more challenging, especially for sensors placed in hazardous settings like fires and explosions. Herein, the utilisation of thermoluminescent microparticles in thermal history sensors is discussed. These transparent dielectric microparticles can store charge carriers for very extended periods due to their wide distribution of trap states. In its most basic form, an Arrhenius expression is strongly temperature-dependent for determining the population of the trap states. When exposed to high temperatures for a brief period, a particle with filled traps will preferentially lose carriers in shallow traps. To ascertain the temperature and timing of the thermal event, this depopulation creates a mark on the particle luminescence. By being exposed to deep ultraviolet, X-ray, beta, or gamma radiation, which fills the traps with charge carriers, particles are prepared many months before a test, if required. No matter if they are embedded in garbage or other inert materials, one or more particles can nevertheless be made to emit light. Laboratory tests using microheaters and high-energy explosives in the field are used to test and analyse the technology. It is demonstrated that a variety of high-explosive conditions may be used to accurately detect temperatures in the $ 200\mathrm{^\circ C} $ 200 ∘ C to $ 500\mathrm{^\circ C} $ 500 ∘ C range using thermoluminescent materials like LiF:Mg,Ti, MgB4O7:Dy,Li, and CaSO4:Ce,Tb. The article will provide the utilisation of different luminescent materials for sensing thermal history and analysing the particle luminescence mechanism through different thermal models for developing improved thermal history sensing technologies. The thermal history reconstruction techniques are also discussed to predict the thermal history. Therefore, the article will pave the way to understanding the luminescent properties of thermoluminescent microparticles for developing state-of-the-art thermal history sensors for measuring non-volatile thermal history and temperature in extreme environments such as fires and explosions. [ABSTRACT FROM AUTHOR]

Discovering energy storage materials with rationally controlled trapping and de-trapping of electrons and holes upon x-rays, UV-light, or mechanical force stimulation is challenging. Such materials enable promising applications in various fields, for instance in multimode anti-counterfeiting, x-ray imaging, and non-real-time force recording. In this work, photoluminescence spectroscopy, the refined chemical shift model, and thermoluminescence studies will be combined to establish the vacuum referred binding energy (VRBE) diagrams for the LiSc1−xLuxGeO4 family of compounds containing the energy level locations of Bi2+, Bi3+, and the lanthanides. The established VRBE diagrams are used to rationally develop Bi3+ and lanthanides doped LiSc1−xLuxGeO4 storage phosphors and to understand trapping and de-trapping processes of charge carriers with various physical excitation means. The thermoluminescence intensity of x-ray irradiated LiSc0.25Lu0.75GeO4:0.001Bi3+,0.001Eu3+ is about two times higher than that of the state-of-the-art x-ray storage phosphor BaFBr(I):Eu2+. Particularly, a force induced charge carrier storage phenomenon appears in Eu3+ co-doped LiSc1−xLuxGeO4. Proof-of-concept non-real-time force recording, anti-counterfeiting, and x-ray imaging applications will be demonstrated. This work not only deepens our understanding of the capturing and de-trapping processes of electrons and holes with various physical excitation sources, but can also trigger scientists to rationally discover new storage phosphors by exploiting the VRBEs of bismuth and lanthanide levels. [ABSTRACT FROM AUTHOR]

Thermoluminescence (TL) response of newly synthetic silicon-activated Ca9AlP7O28 nanophosphor doped with different concentrations (0.3–10 mol%) (abbreviated as CAP: Six) were prepared by the sol–gel method. The optimum concentration of Si ions for the best TL response was found to be 0.3 mol% (CAP: Si0.3), which was selected for subsequent dosimetric measurements. Phase purity and the crystal structure of the CAP: Si0.3 sample were identified and verified using X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis, where results obtained confirmed the successful synthetic method used in the preparation of the nanophosphor samples. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) mapping revealed the localization of constituent elements and indicated the homogeneous distribution of Si-ions as well as the feasibility of dopants in the herein sample. The dosimetric properties of the CAP: Si0.3 sample, including glow curve structure, reproducibility, repeatability, dose–response and fading effect, were extensively investigated. The gamma irradiated CAP: Si0.3 sample exhibited a simple glow curve of a single prominent peak centred at 222 ± 1.33°C with considerably high TL intensity (1.22 relative to MTS-700 TLD detector). The relative standard deviation (RSD) of peak areas of CAP: Si0.3 were 5.25 and 2.7% for reproducibility and repeatability studies, respectively. These values of RSD were <10%, so they were acceptable internationally. A good linear dose–response relationship was achieved over a dose range of up to 20 Gy with an excellent correlation coefficient of R2 = 0.9969 and a calibration factor of F = 51.75 × 107 a.u./Gy. Almost no fading was registered from the studied CAP: Si0.3 sample after irradiation. Zeff values were found to be in the range 11.62 to 11.61, which are closely related to that of natural bone (11.3 to 11.8). Minimum detectable dose of CAP: Si0.3 had a value of 11 μGy. The outstanding features of this herein-prepared sample make it a good TLD nanophosphor, very suitable for personnel and environmental dosimetry of γ-radiation within the studied dose range. [ABSTRACT FROM AUTHOR]

The present investigation, aimed to prepare lead silicate glasses doped with samarium ions and to study it's structure, elastic, spectroscopic and thermoluminiscence properties with Al(10−x)Sbx composite influence. The objective of the investigation is to develop TL sustained good laser active resource by means of studying photo and thermoluminiscence properties. In this direction, we have prepared the glass series of Al(10−x)SbxSm0.1Pb30Si59.9 materials (where, 0 ≤ x ≤ 10, with steps of 0, 2, 4, 6, 8 and 10 mol%) after that planned for structural (XRD, FT-IR, DTA, EDS & SEM), Optical (UV & PL) and thermoluminescence characterization. The XRD and SEM studies reveal the glassy behavior of test samples. The EDX analysis signifies the chemical constitutes with atomic weight %. The physical properties such as density and molar volume of glasses were evaluated. The DTA studies of glasses reveal the glass transition and crystallization temperature points. The values of thermal stabilities of glasses found to be purely function of Sb3+ ions. Various structural vibrations of test glass conformed using FT-IR studies. Using ultrasonic velocities of the test glasses, the glasses' micro-hardness was evaluated. From the absorption spectra, the Judd–Ofelt intensity parameters (Ω2, Ω4, Ω6) have been calculated. The PL spectra under stimulation at 402 nm show a prominent reddish–orange emission at 602 nm. The experimental lifetimes (τr) of the 4G5/2 → 6H7/2 (602 nm) luminescence transition were measured using the decay spectral profiles of this transition. The evaluated emission cross-sections (σse), branching ratios (βr), and quantum efficiency (η) allow us to speculate that the lead silicate glasses doped with Sm3+ ions are ideally suitable as potential gain mediums for visible reddish orange lasers pumped directly by readily available 405 nm laser diodes. Quantum efficiencies of the produced glasses are obtained using a decay curve analysis. The emission spectra used to establish the developed glasses' reddish orange emission are used to compute the CIE chromaticity coordinates. It is evident from the stated fluorescent properties that the developed glasses are suited for reddish–orange laser applications, particularly in opto-electronic devices. From all of the values obtained, it can be observed that SAS6 glass code is ideally suited for reddish–orange laser applications. The TL properties are studied at 30 kGy gamma irradiation dose range. The frequency factor and A.E. of glasses were evaluated. This reveals that the TL behavior of glasses is a purely function of Sb3+ ions. Overall, the Al(10−x)SbxSm0.1Pb30Si59.9 glasses prepared are mechanical hard, TL effective, and optically useful resources. [ABSTRACT FROM AUTHOR]

Persistent luminescence is reported for a series of SrAl2O4 single crystals co-doped with 1.0 mol% Eu2O3 and (0.5–3.0 mol%) Nd2O3. Crystals were successfully grown under an Ar atmosphere in an optical floating zone furnace and consisted of a single phase with a monoclinic structure. The maximum intensity of the photoexcitation spectra (PLE) of all samples peaked at 421 nm. Under excitation at 421 nm, the photoluminescence (PL) spectra showed a broad emission in the visible region centered on 522 nm, which corresponds to the Eu2+ 4f65d1 → 4f7 transition, and three additional emissions in the near infrared region, corresponding to the 4F3/2 → 4I9/2 (880/907 nm), 4F3/2 → 4I11/2 (1062/1114 nm) and 4F3/2 → 4I13/2 (1332 nm) transitions from Nd3+. Thermoluminescence (TL) spectra showed that traps in the conduction band are shallower than that of the singly Eu-doped sample, and their concentration gradually increased with increasing Nd3+ content, reaching a maximum in the crystal prepared with 2.5 mol% Nd2O3. The lifetime of the afterglow decay curve also increased with increasing Nd3+ content of the crystals, reaching a maximum value of almost 35 seconds with 2.5 mol% Nd2O3. A mechanism for the long afterglow is proposed in which Eu2+ electrons are first excited, then transported through the conduction band to defect centers which function as traps (produced by Nd3+ doping), and the thermal energy at room temperature is sufficient to reverse this process, so that equilibrium is established and a long residual luminescence results. [ABSTRACT FROM AUTHOR]

In afterglow phosphors, luminescence appears and can be observed with the naked eye for minutes to hours or more, even after photoexcitation ceases. Red afterglow and photostimulated luminescence (PSL) at 650 nm are studied in CaS:Eu2+, Mn2+ phosphors. Infrared light at 980 nm from a laser diode induces the red PSL for 990 s. Two types of trap states are found to be present in the phosphors by using thermoluminescence (TL). Deep trap states are reflected in a TL peak in the temperature region of 520 K, and are related to PSL. Shallow trap states reflected in the other TL peak at 250 K are related to afterglow. The intensity dependence of photoexcitation on PSL shows that carriers are more easily accumulated in the deep trap states than shallow trap states. Experiments of electron paramagnetic resonance are conducted to discuss the possible origins of PSL and the afterglow. [ABSTRACT FROM AUTHOR]

A long afterglow material CaAl2O4:Eu2+,Pr3+ emitting blue light has been synthesized by a high-temperature solid-phase method. The effect of a series of preparation conditions on CaAl2O4:Eu2+,Pr3+ was first investigated using a single-factor preference method, and the optimal synthesis conditions were then obtained through orthogonal tests. The target products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), elemental mapping, fluorescence spectroscopy, and afterglow properties. The XRD results indicate the successful synthesis of CaAl2O4:Eu2+,Pr3+ materials, which was further verified by XPS analysis. The afterglow properties of the target products were further improved by doping with Nd3+ under optimum conditions obtained from orthogonal tests. The improvement was analyzed through XRD, fluorescence, afterglow and thermoluminescence analysis. The results indicate that doping with Nd3+ in CaAl2O4:Eu2+,Pr3+ materials significantly enhanced the afterglow properties, including an initial brightness of 2318 mcd m−2 and a duration of 26.5 hours. Thanks to its excellent blue long afterglow luminescence, the material is anticipated to have applications in energy-efficient lighting systems and solar energy systems. [ABSTRACT FROM AUTHOR]

Zinc selenide doped with Sn and (Sn, Dy) phosphors has been prepared by firing the samples in an atmosphere of nitrogen gas. The voltage and frequency dependence of electrolyte brightness has been studied. Voltage dependence of electroluminescence (EL) brightness reveals an acceleration collision mechanism in the Schottky barrier at the metal–semiconductor interfaces. EL and photoluminescence (PL) spectra and thermoluminescence (TL) glow curves of these phosphors have also been recorded to understand the nature and mechanism involved in the luminescence process. The trapping parameters are calculated for the glow curves of these phosphors. [ABSTRACT FROM AUTHOR]

With a view to understanding the luminescence mechanism in ZnSe, a systematic study of thermally stimulated luminescence (TSL) of UV ray (3650 Å) irradiated ZnSe:Ag and ZnSe:(Ag, Gd) phosphors has been undertaken. TSL glow curves of these phosphors are recorded in the temperature range 110–340 K. The TSL parameters like trap depth, frequency factor, order of kinetics, and capture cross‐section of the glow peaks are evaluated employing Cutie's method, various heating method, and peak shape method. [ABSTRACT FROM AUTHOR]

Terrestrial gamma‐ray flashes (TGFs) and other high‐energy radiation phenomena related to thunderstorms remain incompletely understood since their discovery nearly 30 years ago. Space and ground‐based platforms have provided insights, but limitations exist in temporal resolution, signal‐to‐noise ratios, and proximity to events. This study presents findings from a balloon‐borne gamma‐ray spectrometer flown into a thunderstorm over northern Mississippi on 19 June 2023. The instrument detected three distinct millisecond‐duration TGF events correlated with lightning strikes. Sustained gamma‐ray glows lasting up to 2 minutes were measured and tied to thunderstorm electrostatic fields. Notably, radiation was observed during a direct lightning strike to the payload. This complex 800‐millisecond event reveals insights into radiation from leader propagation and return strokes. These findings from a single balloon flight demonstrate the prevalence of energetic processes within thunderstorms. Finally, the balloon platform offered an exceptional combination of temporal resolution and validation capabilities to advance the understanding of thunderstorm radiation motivating future follow‐up studies. Plain Language Summary: In this study, a specialized balloon carrying a radiation detector was flown into a thunderstorm to better understand the bursts and glows of high‐energy radiation associated with thunderstorms. The balloon detected several bursts of radiation tied to lightning strikes, as well as more sustained glows of radiation. Key Points: A balloon‐borne gamma‐ray spectrometer was flown into a thunderstorm detecting various high‐energy radiation events: terrestrial gamma‐ray flashes and gamma‐ray glowRadiation detected during a direct lightning strike to the payload at 11.9 km altitude revealed insights into high‐energy emissionsThe variety of radiation spikes and glows observed indicates the prevalence and potential ubiquity of energetic processes in thunderstorms [ABSTRACT FROM AUTHOR]

In the present study, the dosimetric features of pink Himalayan salt pellets were studied. Energy dependence exhibited an over response up to 100 keV with a maximum factor of ~ 10 at 33 keV. The maximum angular dependence of ~ 46% was observed at 90° angle of incidence. The TL response was found to be dose rate independent and showed a good reproducibility with < 5% COV. The sample sensitivity was comparable to TLD-100 (beyond 500 mGy). The effective atomic number (Zeff) was found to be 15.20. Based on these dosimetric features, pink Himalayan salt can be a good potential candidate for therapeutic dosimetry applications. [ABSTRACT FROM AUTHOR]

The solution combustion synthesis method is employed to prepare Magnesium, Zinc, Aluminate doped with dysprosium (Dy3+) using the general formula Mg(1‐x‐y) Zn(y)Al2O4:xDy (x = 0.05 and y = 0.3 mol%). From X‐ray diffraction studies, the crystal structure belongs to a cubic close‐packed spinel structure with space group Fd3ˉm and an average crystallite size is 26.18 nm. In the Fourier transform infrared spectra, the peaks at 683.69 cm−1, 503.12 cm−1 correspond to the AlO6 groups. The peak temperature (Tm) from the Thermoluminescent glow curve is recorded at 235°C, 237°C, and 235°C, at irradiation doses of 600 Gy, 800 Gy, and 1000 Gy, respectively. The kinetic parameters are evaluated from the thermoluminescent glow curve by calculating the activation energy (E), order of kinetics (b), and frequency factor (s−1). Nanophosphor Mg0.65Zn0.3Al2O4:0.05Dy shows sub linear dose relationship at doses 600–675 Gy and 925–1000 Gy. Further, at doses between 675 and 925 Gy, it shows a super linear relationship. The optimum activation energy (E) of 0.77–0.82 eV and negligible fading make it suitable for high radiation thermoluminescent dosimetry. [ABSTRACT FROM AUTHOR]

The current research aims to develop an optically active, thermally luminescent, and radiation-shielding glass resources. For that, we have planned to develop a glasses of the chemical composition Ba(25-x)La15Si60Nix (where, 'x' = 0, 0.2, 0.4, 0.6, 0.8 & 1.0 mol%). There after the developed glasses are planned for structure, physical, mechanical, radiation shielding, optical and thermoluminescence characterization. The XRD & SEM studies reveal the glassy behavior. The EDS analysis signifies the chemical constitutes with atomic weight %. The physical properties such as density (~ 2.625 gm/cm3), molar volume (~ 48.48 cm3 mol−1) and refractive index (1.649) of glasses are evaluated. The DTA studies of glasses reveal the GTT (~ 429.5 °C) and thermal stabilities (1.593) evolutions are purely function of Ni2+ ions. Using ultrasonic velocities of the test glasses, the glasses' micro-hardness (~ 2.82 GPa) was evaluated. Radiation shielding properties such as RPE (~ 36.55%) and MAC (~ 16.556) reveal the shielding behavior is purely a function of Ni2+ ions. Using the optical absorption spectra, the bandgap (~ 1.21 eV) of the glasses evaluated. These values also purely function of Ni2+ ions. Using the photoluminescence spectra the luminescence analysis of glasses studied. The variations in values of emission cross section (~ 1.21 × 109, cm2) and Chromacity colour co-ordinates also suggesting emission range of glasses is purely function of Ni2+ ions. The TL properties are studied at 0 and 50 kGy gamma irradiation dose range. The frequency factor (~ 3.062 × 1021, S−1) and A.E. (~ 1.798 eV) of glasses were evaluated. This reveals that the TL behavior of glasses is a purely function of Ni2+ ions. Overall, the NSBL glasses prepared are mechanical hard, TL effective, optical and radiation shielding resources. [ABSTRACT FROM AUTHOR]

The present investigation reports the swift heavy ion induced effects on cerium oxide (CeO2) thin films. These thin films were deposited on Si (111) substrates by the electron-beam evaporation method and irradiated by a 100 MeV O7+ ion beam with different ion fluences. X-ray diffraction analysis of these films confirms the stable fluorite phase of CeO2 even after the higher fluence of irradiations. Raman measurement also supports the presence of the F2g phase of CeO2 and the presence of defect states. The Gaussian deconvolution of photoluminescence (PL) spectra reveals various defect-associated peaks. The broad peaks in the PL spectra are associated with oxygen vacancies and are red-shifted (494–520 nm) with ion fluences. The surface morphological images show the modification in the surface roughness with ion irradiation and the re-growth of smaller circular-formed nanoparticles on the surface is observed at the fluence of 5 × 1011 ions/cm2. Magnetic measurements show an enhancement in magnetic ordering with ion irradiation. All the samples demonstrate room temperature ferromagnetism with magnetic saturation (Ms) up to 14.57 emu/cm3. The saturation magnetization in irradiated thin films is directly correlated to the area under the peak of defect-associated PL emission. The mechanism such as the oxygen vacancy-based F-center exchange model is considered to understand the enhancement of ferromagnetism in ion irradiated CeO2 thin films. Some popular theoretical models are also employed to determine various magnetic parameters. [ABSTRACT FROM AUTHOR]

Phototransferred thermoluminescence (PTTL) of natural fluorite induced by 470 nm blue-, 525 nm green-, and 870 nm infrared light is reported. Although its conventional thermoluminescence (TL) glow curve measured during heating to 600 °C has six peaks, only five are reproduced under phototransfer. One of them corresponds to a hole trap. The sixth peak counterintuitively increases in intensity with illumination in a change suggestive of competition effects involving deep electron traps. The dependence of PTTL intensity on duration of illumination for each PTTL peak is analyzed using phenomenological and kinetic models as systems of acceptors and donors with the number of the latter informed by experiment. The intensity of PTTL increases with the temperature of illumination with an activation energy of thermal assistance of 0.14 ± 0.01 eV and decreases at elevated temperatures with an activation energy of thermal quenching of 1.1 ± 0.3 eV. The long-term behavior of time-response profiles and the interaction of holes with stimulated electrons as studied by stability theory show unstable critical points. Supplementary tests show that exposing CaF2 to UV illumination achieves the same effect as beta irradiation, and any resultant peaks relate to conventional TL rather than phototransfer. [ABSTRACT FROM AUTHOR]

We report the existence of a hole trap in α-Al2O3:C,Mg as determined using thermoluminescence (TL) and optically stimulated luminescence (OSL). The associated experiments are based on the hypotheses that if a TL glow peak is associated with a hole trap in the glow curve of α-Al2O3:C,Mg, that hole trap will not participate in any light-induced electron-transfer process and its removal will not cause the OSL intensity to decrease. To examine the first hypothesis, a TL glow curve was recorded at 1 °C/s to establish the position of glow peaks. There is a high intensity peak at 184 °C (labeled as peak IV) and eight secondary peaks at 48, 80, 108, 228, 288, 320, 386, and 426 °C (peaks I, II, III, and V–IX). The light-induced charge transfer between various electron traps associated with the peaks was studied. This study reveals that all peaks except the one at 228 °C (peak V) participate in the charge-transfer process. A test of the second hypothesis shows that peak V is also not reproduced by illumination (phototransfer), and the depletion of this peak does not influence the charge-transfer process. An additional study on the effect of temperature on the TL and OSL intensity was carried out to further assess the nature of the charge traps associated with the peaks. The depletion of peak V does not affect the OSL intensity. The results from both experiments are clear evidence consistent with the hypothesis that the charge trap associated with peak V is a hole trap. [ABSTRACT FROM AUTHOR]

Phototransferred thermoluminescence (PTTL) of Al2O3:C,Mg induced by 470 nm blue, 525 nm green, and 870 nm infrared light is reported. Although its conventional TL glow curve measured during heating to 600 °C has seven peaks (labeled I–VII), only peak II is reproduced under phototransfer, except when the sample is preheated to 180 °C when peak IV also re-appears. The dependence of PTTL intensity on the duration of illumination for both PTTL peaks is analyzed using phenomenological and kinetic models as systems of acceptor and donors, with the number of the latter determined by experiment. The intensity of PTTL increases with the temperature of illumination with an activation energy of thermal assistance of either 0.015 ± 0.002 or 0.047 ± 0.002 eV when either 470 or 525 nm light is used but decreases at elevated temperatures with an activation energy of thermal quenching equal to 0.51 ± 0.02 eV independent of illumination wavelength. The long term behavior of time-response profiles for a system of one acceptor and a single donor, as an exemplar, as studied by stability theory, shows an unstable critical point. Mechanisms for the PTTL are discussed and the emission is ascribed to electron centers in the oxygen sub-lattice. [ABSTRACT FROM AUTHOR]

The catalyst surface was processed in the high-voltage electrical discharge device in oxygen environment. Continuous active oxide centers formed on the surface and complete filling of the surface with oxygen occur, and its thermo-physical properties, thermo-luminescence curves, scanning electron microscope and ESR spectrometers were studied. It was determined that the activity of the catalyst at values of the absorbed dose D ≤ 2 1 kGy is many times higher than that of conventional catalysts. Thus, due to the sorption volume of the surface, the volume of the product formed in the liquid phase increases by 1.6 times. [ABSTRACT FROM AUTHOR]

Fireproof sealing technology is widely used in industrial, commercial, and other public buildings, so the performance of fireproof sealing materials in high temperatures or fire environments must be taken into account as an important factor. Fireproof sealant is considered to be a highly effective adhesive for sealing and fireproofing purposes. To explore its thermal decomposition mechanism and estimate its pyrolysis behaviors, a series of thermogravimetric experiments from 10 K/min to 60 K/min coupled with Fourier transform infrared spectroscopy analysis technology were performed. The results indicated that the thermal decomposition of the fireproof sealant could be divided into three reactions: the degradation of ammonium polyphosphate, melamine, and acrylic acid. In addition, the pyrolysis behavior of the fireproof sealant was compared under two kinds of atmosphere (nitrogen and air). Furthermore, the initial kinetic parameters in the nitrogen atmosphere were calculated based on model-free methods including the Friedman, KAS, and Starink methods. The average activation energy of three reactions obtained by the three methods was 108.32 kJ/mol, 200.46 kJ/mol, and 177.10 kJ/mol, respectively, while these obtained parameters were hard to regenerate, the thermogravimetric curves were accurately based on the established pyrolysis reaction scheme, with the existence of clear deviations. Therefore, a global heuristic optimization algorithm, Shuffled Complex Evolution (SCE), was selected to optimize 14 parameters (including activation energies and the pre-exponential factors) and the optimized pyrolysis results agreed well with the experimental data, even at the extra heating rate, with the correlation coefficient for the mass loss and mass loss rate being reaching up to 0.9943 and 0.9019, respectively. The study indicated that the SCE algorithm showed an appropriate potential to estimate the pyrolysis behavior of an unknown thermogravimetric experiment group. [ABSTRACT FROM AUTHOR]

This study investigated the thermoluminescence properties of undoped CaF2 nanoparticles synthesized via co-precipitation with ethanol. X-ray diffraction revealed pure CaF2 nanoparticles with a complete cubic structure and an average crystallite size of 36.5 nm. Scanning electron microscopy confirmed the nanoscale size, averaging 51.23 nm. Electron dispersive spectroscopy analysis showed that the sample mainly consists of Ca and F, with oxygen potentially introducing defects in the crystal structure. Synthesized nanoparticles TL glow curves exposed to 7 mGy of 90Sr beta rays exhibited a prominent peak at 205 oC in thermoluminescence glow curves, likely due to oxygen-induced defects that act as thermoluminescence activators. The thermoluminescence activating energy and the frequency factor of the CaF2 nanoparticles were determined using initial rise methods of approximately 0.83 eV and 5.99 x 10-19, respectively. [ABSTRACT FROM AUTHOR]

This study delves into the intricacies of isothermal decay analysis applied to thermoluminescence (TL) peaks, focusing on determining kinetic parameters. The study challenges the conformity of the trap responsible for the ITL signals to first, second, or general-order kinetics, supported by the non-conforming decay pattern and the inference of two overlapping first-order TL peaks. This work enhances the understanding of TL peaks and establishes a reliable methodology for characterizing luminescence mechanisms in materials, contributing to advancements in luminescence dosimetry research. These observations lead to the conclusion that the TL data originates from more than one trap, and based on existing literature, it is inferred that there are two overlapping first-order TL peaks. The investigation involves the consideration of isothermal decay data at distinct temperatures (T = 250, 260, 270, 280, and 290°C) and explores challenges associated with achieving precise linear fits for different kinetic order values (b). The nature of decay is interpreted based on the monomolecular theory, suggesting adherence to a first-order process. ITL curves were deconvoluted into two exponential decay curves. The slopes of the regression lines provide activation energy (E) values for curve1 and curve2, respectively: E1 = 0.99±0.16 eV and E2 = 1.32±0.18 eV. The frequency factor (s) is determined from the intercept of the regression line: s1 = 1.32x108 s-1 and s2 = 1.77x1012 s-1. [ABSTRACT FROM AUTHOR]

A series of Sr1−xZr4(PO4)6:xPr (x = 0, 0.01, 0.03, 0.05, 0.07, and 0.09) nanophosphors were prepared by simple sol–gel technique. The crystal structure, vibrational properties, surface morphology, elemental composition, and particle size were investigated using X-ray diffraction-Rietveld refinements, FTIR, SEM-EDAX, and TEM techniques. The effect of dopant concentration of Pr3+ ions in SrZr4(PO4)6 nanophosphors was analysed, and their photoluminescence properties were investigated along with lifetime measurements. Under 448 nm excitation, due to 3P0–3F2 transition of Pr3+ ions, it shows intense reddish emission at 650 nm. Energy-level diagram explains energy transfer mechanisms and concentration quenching mechanisms in detail. The appropriate incorporation of dopant ions (x = 0.03 mol%) showed potential candidates for efficient plant growth n-UV LED. Further, thermoluminescence properties of UV light, Ag and Ni ions irradiated Pr3+ ions doped SrZr4(PO4)6 phosphors were analysed, and glow curves were recorded. The TL studies reveal that SrZr4(PO4)6:Pr3+ phosphors may be a potential candidate as dosimetry materials for low radiation measurement. [ABSTRACT FROM AUTHOR]

In 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. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) is increasing in extent and intensity across the globe. It has been shown to interfere with animal sensory systems, orientation and distribution, with the potential to cause significant ecological impacts. We analysed the locations of 102 mountain lions (Puma concolor) in a light-polluted region in California. We modelled their distribution relative to environmental and human-disturbance variables, including upward radiance (nearby lights), zenith brightness (sky glow) and natural illumination from moonlight. We found that mountain lion probability of presence was highly related to upward radiance, that is, related to lights within approximately 500 m. Despite a general pattern of avoidance of locations with high upward radiance, there were large differences in degree of avoidance among individuals. The amount of light from artificial sky glow was not influential when included together with upward radiance in the models, and illumination from moonlight was not influential at all. Our results suggest that changes in visibility associated with lunar cycles and sky glow are less important for mountain lions in their selection of light landscapes than avoiding potential interactions with humans represented by the presence of nearby lights on the ground. This article is part of the theme issue 'Light pollution in complex ecological systems'. [ABSTRACT FROM AUTHOR]