Thermoluminescence Peak Intensity Research Articles

Investigation of zinc polycarboxylate cement used in dental treatments in terms of retrospective dosimeter.

Zinc polycarboxylate cement is one of the few dental materials that demonstrate true adhesion to tooth structure. It is suitable for use in living organisms without causing harm. Its strong adhesion to teeth and low level of irritancy are two important parameters for the dental applications. In this study, the dosimetry properties of zinc polycarboxylate cement using thermoluminescence (TL) method were investigated and determined the effectiveness of its use as a good dosimeter. According to the results of this study, the sample shows a good TL properties with three main peaks found around 140°C, 220°C and 330°C. It has a wide linear dose response between 72 Gy and 2.3kGy and good reusability of the TL peak found at 330°C. Unfortunately, the TL peak intensity values are rapidly faded within a short waiting time interval. Zinc polycarboxylate cement, which is frequently used in dental crowns, can be used as a retrospective dosimeter for measuring the amount of radiation in space studies and nuclear accidents due to its wide linear dose-response curve in the high dose region.

Thermoluminescence properties of the rock naturally annealed for thousands of years by flames from the earth's inner layers.

The gas leak in Chimaera near Çıralı, Antalya, has been active for thousands of years. It is also known to be the source of the first Olympic flame in the Hellenistic period. The sample taken from the Chimaere seepage annealed for thousands of years was determined to be calcite-magnesian (Ca, Mg)O3 . In this study, thermoluminescence (TL) properties of calcite-magnesian annealed for thousands of years in the fire caused by methane gas were investigated for particle size, dose-response, heating rate, and fading experiments. It exhibits a clear TL glow curve with two distinct peaks positioned at 160 and 330°C, and its shape is not affected by variation in applied dose and reproduciility of experiment. There is a wide linear relationship between TL output and applied dose up to 614 Gy. Although the positions of the TL peaks are stable with the cycle of measurement, a poor reusability was observed in terms of the area under the TL glow curve and peak intensity.

Thermoluminescence of UV-irradiated α-Al2O3:C,Mg

The effects of ultraviolet (UV) radiation exposure on the thermoluminescence (TL) of aluminium oxide co-doped with carbon and magnesium (Al2O3:C,Mg) are reported. An Al2O3:C,Mg single crystal was investigated as a potential UV TL dosimeter after exposure to a Hg lamp radiation. The TL peak intensity and area under the curve signals were investigated as a function of the UV exposure time. Intense TL signal was obtained after UV radiation, and the area of the main TL peak at 456 K exponentially increasing with UV exposure time (within 10–120 s), with a trend for saturation for long irradiation times These results were interpreted against similar measurements using beta radiation, showing that the same defects are involved in the TL response for both types of radiation, while the different irradiation response to the two types of radiation was related to the differences in the energy dissipation characteristics, and how they affect the concentration of F-type/F-aggregate centers.

Effect of γ-radiation on TL, ESR and evaluation of trapping parameters of K2Ca(SO4)2:X (X = Dy or Eu) phosphors

ABSTRACTThe present phosphor K2Ca(SO4)2, doped by dysprosium and europium, is synthesized by the solid-state diffusion method. The doping concentration varied from 0.1 to 0.5 mol% by weight. A phosphor is studied for X-ray powder diffraction, surface morphology analytical scanning electron microscopy and analyzed by energy-dispersive X-ray spectroscopy. The prepared phosphor K2Ca(SO4)2, doped by Dy and Eu, has been characterized for thermoluminescence (TL) glow curve, showing maximum peak temperatures at 176°C and at 200°C, respectively. TL peak intensity of K2Ca(SO4)2: Dy and Eu was compared with the standard TLD CaSO4:Dy phosphor. Both phosphors show the dose linearity ranging from 20 to 240 Gy doses of γ-rays of 60Co source at room temperature. Negligible fading has been observed when irradiated with γ-rays and stored for 60 days without taking any care from sunlight. The TL materials were used in powder forms. The linearity of ESR response with dose for powder forms of K2Ca(SO4)2: Dy was also studied using the signals at g = 2:0039 (SO3−) and at g = 2:02282 (SO4−). It was observed that the range of linearity of dose response extended between 20 and 240 Gy. Kinetic parameters have been calculated using three different methods: Chen's peak shape method, various heating rate method and initial rise method. To study the heating rate method, the glow curve was recorded for the heating rate as 1°C, 3°C, 5°C, 7°C, 9°C each time. Electron spin resonance (ESR) shows the ionic radical formation during γ-irradiation, which is responsible for TL. The effect of temperature and microwave power on the ESR signal was also studied.

Carbonate thermoluminescence and its implication for marine productivity change during the Permian-Triassic transition

The Permian-Triassic (P-Tr) crisis was the largest mass extinction of the Phanerozoic and eliminated over 90% of marine species. However, the nature of marine productivity changes during the crisis is a matter of on-going debate. Here, thermoluminescence (TL) measurements from 144 bulk carbonate samples from Meishan (South China) show two levels of variation in TL peak intensities at ~270 °C. The first-order variation is characterized by a rapid, nearly three-fold increase. A secondary variation is interpreted to record periodic fluctuations on a Milankovitch scale (~20-kyr rhythm). The periodic variations of TL are negatively correlated with Mn concentrations, suggesting primary productivity is a key factor controlling the TL peak intensity by photo-reduction of particulate Mn in the presence of organic matter. Therefore, the periodic fluctuations of TL were likely controlled by primary productivity changes on orbital timescales. A significant rise of TL peak intensities across the P-Tr boundary represents the rapid increase of dissolved Mn associated with enhanced marine productivity and/or oceanic anoxia.

Thermoluminescence dosimetric properties of silicon carbide (SiC) used in industrial applications

Silicon Carbide (SiC), also known as carborundum, has been found to be widely useful as a substrate and wide band gap semiconductor in radiation resistant optoelectronic devices. The aim of this study is to discuss the thermoluminescence (TL) properties of silicon carbide (SiC) used in industrial applications for dosimetric purposes. Basic TL properties of these materials such as dose response, heating rate, fading effect and reproducibility have also been investigated. The largest TL peak intensity was observed at 400–1000 μm of particle size for the dosimetric peak (≈250 °C). A wide linear region between 12Gy and 2.3 kGy was observed. The good reproducibility was obtained with small standard deviation but low-temperature peaks were completely faded after 30 min storage in a dark room.

Effect of co-activation on the thermoluminescence and photoluminescence properties of nano-crystalline K2Ca2(SO4)3:Eu,Cu

The effect of co-doping and change in dopant concentration on thermoluminescence (TL) properties of K2Ca2(SO4)3:Eu,Cu has been studied by varying the concentration of the two dopants europium and copper (0.05, 0.10, 0.20, 0.30 and 0.40 mol% equally divided between Eu and Cu). Chemical co-precipitation technique was used to prepare the co-doped phosphor K2Ca2(SO4)3:Eu,Cu. Using Williamson-Hall plot in the X-ray diffraction pattern of the phosphor, the size of the crystallites was estimated to be around 51.3–73.6 nm. Maximum TL sensitivity was obtained for 0.2 mol% concentration (0.1 mol% Eu and 0.1 mol% Cu). The co-doped phosphor was compared for its TL sensitivity with that of the singly doped phosphors K2Ca2(SO4)3:Eu, and K2Ca2(SO4)3:Cu and the standard TL dosimeter LIF:Mg, Ti (TLD-100). Higher TL peak intensity of co-doped phosphor compared to the singly doped phosphors K2Ca2(SO4)3:Eu and K2Ca2(SO4)3:Cu has been explained on the basis of energy transfer between the dopants. Photoluminescence studies of the co-doped and the singly doped samples confirm a positive energy transfer from Cu2+ to Eu2+. A linear TL response curve over a wide range of doses (10 Gy to 1 kGy) is a key factor that makes the present phosphor quite capable for dosimetric purposes.

Correlation between thermoluminescence and optically stimulated luminescence of α-Al2O3:C,Mg

The optically stimulated luminescence (OSL) and thermoluminescence (TL) signals of an Al2O3:C,Mg single crystal were investigated as a function of the heating temperature and illumination time before readout, respectively. The TL and OSL results were analyzed in complementary ways, including the area under the curve, whole range and partial integration, and peak intensity. A correlation between the continuous decay of the main TL peak intensity (at 185 °C at a heating rate of 1 °C/s) against blue light (470 nm) illumination times and the decay of the OSL signal for higher temperatures was found. Both these results showed that the emptying of the OSL active trap was closely related to the emptying of the trap related to the main TL peak, indicating a correlation of both phenomena.

Thermoluminescence properties of Tb3+-doped CaO–Al2O3–B2O3-based glasses

In this study, the thermoluminescence (TL) characteristics and X-ray radiation response properties of 35CaO–15Al2O3–50B2O3:xTb4O7 (x = 0.25, 0.5, 1.0, 2.0, and 4.0 mol%) glasses were evaluated. These glasses, prepared by a conventional quenching method, were transparent and non-hygroscopic. The TL spectra showed a green band emission (400–600 nm) arising from 4fn–4fn forbidden transitions of the Tb3+ ions. A TL glow peak was observed at 360 K in all the glasses at different Tb concentrations. Among them, the 1.0, 2.0, and 4.0 mol% Tb-doped glasses exhibited excellent linearity over the 1.0 mGy–10 Gy irradiation dose range. The TL peak intensity decreased to ∼60% after 1 h, ∼45% after 24 h and ∼30% after 72 h.

Synthesis and luminescence studies of Tb-doped MgO-MgAl2O4-Mg2SiO4 ceramic for use in radiation dosimetry

In the present work, MgO ceramic samples with different terbium concentrations were produced and the Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) properties analyzed and discussed, aiming the use in radiation dosimetry. The samples were produced using MgO, Mg(NO3)2·6H2O, Al2O3, SiO2 and Tb(NO3)3·6H2O precursors in stoichiometric concentrations with five different terbium concentrations between 0.1 and 0.5 mol% and after, heat-treated at high temperature ~1500 °C. X-ray diffraction measurements on samples showed the formation of MgO as principal phase, and others in low concentration due to MgAl2O4, Mg2SiO4 and Tb4O7 phases. The TL glow curve of samples showed an intense and well-defined peak having the maximum at ~210 °C and other less intense at ~350 °C. The sample with 0.1 mol% of terbium concentration presented highest luminescence peak when compared to the other samples. The relationship between 210 °C TL peak intensity and dose was linear to doses between 1 and 20 Gy and the minimum detectable dose obtained by interpolation taking into account three times the standard deviation of the zero dose reading, was ~40 μGy. A fading of ~20% during the first 5 hours after irradiation of 210 °C peak was observed. TL emission spectra showed strong emission lines due to Tb3+ ion. The OSL signal presented a linear behavior to doses between 1 and 10 Gy using 532 nm wavelength stimulation.

Photoluminescence and Thermoluminescence Properties of Sol-Gel Auto-Combustion Driven Mg2SnO4 Nanophosphor

Nanocrystalline Mg2SnO4 nanophosphor was synthesized by a facile sol-gel auto-combustion method calcined 800°C for 1 h. The X-ray diffraction pattern showed that the nanopowder has a cubic inverse spinel polycrystalline structure with an average crystallite size of about 20 nm. The photoluminescence spectra were measured at 84−300 K, and the broad emission band was obtained in the wavelength range of 400−500 nm. Photoluminescence at 120 K showed the highest emission band centered around 414 nm. The thermoluminescence (TL) glow curve showed an increase in TL peak intensity with UV irradiation time due to the increasing number of inherent traps created by UV irradiation. The maximum TL intensity was found for 30 min UV exposure. Activation energies of the trapping centers were found between 0.39 eV and 0.48 eV. The frequency factor of the main glow-peak was also evaluated in the 3.03 × 106–4.26 × 107 s−1 range for UV irradiated phosphor. The decrease in activation energy and frequency factor with increasing UV exposure time may attribute to the decrease in trap depth. The calculated trap parameters related to the glow peak show this phosphor may be useful in radiation dosimetry applications.

Thermoluminescence investigations of sol–gel derived and γ-irradiated rare earth (Eu and Nd) doped YAG nanophosphors

Nanocrystalline YAG doped with Eu3+ and Nd3+ has been synthesized by a sol–gel technique. The prepared nanophosphors were calcined and characterized by XRD, SEM. The XRD analysis revealed well-defined cubic phase. Electron microscopy showed spherical morphologies with an average size of 15–20nm. The thermoluminescence (TL) properties of as prepared nanophosphors were investigated after γ-irradiation using 60Co source at room temperature. It has been found that there is a prominent TL glow peak at 290–295°C for the as prepared doped samples. The TL glow curve showed variation in TL peak intensity as the concentration of dopant is changed. Kinetic data and trap depth for the synthesized samples were calculated by a peak shape method. It has been found that TL response is nonlinear in the range 0.29–1.16kGy. This paper discusses about the optimal doping concentration of Eu and Nd in YAG nanophosphors.

Crystal structure and kinetic studies of gamma exposed Ca3B2O6:Tb3+ nanophosphor

This paper reports the crystal structure, thermoluminescence glow curves and kinetic studies of the terbium (Tb3+) doped calcium borate (Ca3B2O6) nanophosphors. The crystal structure has rhombohedral symmetry with space group R-3c. The lattice parameters after refinement have been found to be a = b = 8.623 A and c = 11.853 A and V = 763.45 A3. The analyses of structure and morphology of the nanophosphor are carried out by X-ray diffraction and transmission electron microscopy. In gamma exposed samples, the thermoluminescence glow curve consists of a single thermoluminescence glow peak at 414 K and a shoulder at 496 K. The dependence of the dose and heating rate on the thermoluminescence peak intensity is investigated. The thermoluminescence response curve shows subliner response. Kinetic parameters such as activation energy (E), order of kinetics (b) and frequency factor (s) of gamma irradiated materials are determined by using a thermoluminescence Anal computer program and compared with the values calculated by Chen’s formulae.

The investigation of usage of fluorapatite mineral (Ca5F(PO4)3) in tooth enamel under the different pre-irradiation thermal treatments

Fluorapatite Ca5F(PO4)3 is a kind of important thermoluminescence dosimeter (TLD) material, because the effective atomic number of fluorapatite is close to that of human bones and teeth. In the present study, thermoluminescence (TL) properties of fluorapatite mineral in tooth enamel under the different annealing temperatures with various annealing times were investigated. This study reveals that the fluorapatite in tooth enamel exhibits TL properties. Annealing of the sample affects extremely the TL glow curve and causes a huge enhancement in the sensitization of TL peak. The sample annealed at 1000°C about 120min gives best TL peak intensity (150 factors than un-annealed sample) and has a distinct peak around 230°C. Also, the best reproducibility was observed for 1000°C annealed sample temperature while un-annealed sample shows the worst reproducibility. Moreover, a good linearity in dose response is observed in the samples annealed at 400°C and 700°C.

Effect of capping agent concentration on thermoluminescence and photoluminescence of copper-doped zinc sulfide nanoparticles.

Copper-doped zinc sulfide (ZnS:Cu) nanoparticles with varying concentrations of capping agent were prepared using a chemical route technique. These particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy and X-ray diffraction (XRD). Optical absorption studies showed that the absorption edge shifted towards the blue region as the concentration of the capping agent increased. Using effective mass approximation, calculation of the nanoparticle size indicated that effective band gap energy increases with decreasing particle size. The thermoluminescence (TL) properties of sodium hexameta phosphate (SHMP)-passivated ZnS:Cu nanoparticles were investigated after UV irradiation at room temperature. The TL glow curve of capped ZnS:Cu showed variations in TL peak position and intensity with the change in capping agent concentration. The photoluminescence (PL) spectra of ZnS:Cu nanoparticles excited at 254 nm exhibited a broad green emission band peaking around 510 nm, which confirmed the characteristic feature of Zn(2+) as well as Cu(2+) ions as the luminescent centres in the lattice. The PL spectra of ZnS:Cu nanoparticles with increasing capping agent concentrations revealed that the emission becomes more intense and shifted towards shorter wavelengths as the sizes of the samples were reduced.

Thermoluminescence properties of Mn-doped CaYAl3O7 phosphor irradiated with ultra-violet, mega-voltage and gamma radiation

Low temperature combustion synthesis was employed for the preparation of CaYAl3O7(Mn2+) phosphor. X-Ray diffraction (XRD) patterns were recorded to confirm the phase formation. Estimated particle size was found to be ~19.9nm by using the Debye Scherrer׳s formula. FTIR study confirms the formation of CaYAl3O7 compound, escape of nitrates and other organic products. Thermoluminescence (TL) glow curves of the prepared phosphor were recorded after exposing the sample with Ultra-violet (UV), 6-Mega-voltage (MV), 16-MV and Co-60(Cobalt-60, 1.25-MeV average gamma energy) radiation. Trapping parameters namely activation energy (E), order of kinetics (b) and frequency factor(s) of main peak, centered around 186°C in the sample irradiated with UV source for 20min, were determined using glow curve shape (Chen׳s) method. It has been observed that the TL peak intensity increases with increasing the exposure from UV source. Also with increases the energy of incident radiation a decrease in TL peak intensity were observed. This could be due to higher penetration power and less absorbance of incident beam in the phosphor material. Analysis suggests that possibility of utilizing this phosphor in futuristic low and high energy dosimetric applications as well as in solid state lighting devices.

Thermoluminescence investigation of sol–gel derived and γ-irradiated SnO2:Eu3+ nanoparticles

Nanocrystalline tin oxide (IV) doped with Eu3+ has been synthesized by sol–gel technique. The prepared SnO2:Eu3+ nanoparticles were calcined and characterized by XRD, SEM, TEM and FTIR. The XRD analysis revealed well crystallised tetragonal rutile phase. Electron microscopy showed spherical morphologies with an average size of 15–20nm. The thermoluminescence (TL) properties of SnO2:Eu3+ nanoparticles were investigated after γ-irradiation using 60Co source at room temperature. The TL glow curve showed variation in TL peak intensity as the concentration of dopant is changed. It has been found that TL response of linear in the range 0.5–2.0kGy. This paper discusses about the optimal doping concentration of Europium in SnO2 nanoparticles and its dosimetric application has also been studied.

Thermoluminescence characteristics of high gamma dose irradiated natural quartz

The present investigation elaborates the thermoluminescence characteristics of colourless natural quartz irradiated with high dose (30–280kGy) of gamma radiation from a 60Co source. Two thermoluminescence glow peaks in the temperature ranges of 491–499K and 634–666K were observed in irradiated quartz. Colour transitions, dose response on the thermoluminescence peak intensity, shift in peak temperature and defect production were studied. The kinetic parameters (activation energy, order of kinetics, frequency factor, etc.) of natural quartz have also been determined.

The 110<sup>0</sup> C Thermoluminescence Peak as a Probe in Bioactivity Study of the 58S Sol-Gel Bioactive Glass

Results of the present study provide strong indications towards the effective application of the 110oC Thermoluminescence (TL) peak in discriminating between different bioactive responses for the case of the 58S bioactive glass. The in vitro bioactivity of this glass in the form of powder in SBF solution was tested for various immersion times, ranging between 0 and 6 days. This TL peak is ubiquitously present in all 58S samples, for all immersion times. The intensity of the110oC TL peak was proven to be very sensitive to the different bioactive responses, indicating a strongly decreasing pattern with increasing immersion time in SBF, easily identifying thus the loss of silica. This loss is reflected to the decrease of the 110oC TL peak intensity, which appears to be fast even for the shorter immersion times. The 110oC TL glow peak intensity and sensitization could also be yielding a time scale regarding the beginning of some among the several stages included in the bioactivity sequence.

Thermoluminescence as a probe in bioactivity studies; the case of 58S sol–gel bioactive glass

The formation of a carbonated hydroxyapatite (HCAp) layer on the surface of bioactive materials is the main reaction that takes place upon their immersion in physiological fluids. To date, all techniques used for the identification of this HCAp formation are rather time consuming and not well suited to detailed and rapid monitoring of changes in the bioactivity response of the material. The aim of this work is to explore the possibility of using thermoluminescence (TL) for the discrimination between different bioactive responses in the case of the 58S bioactive glass. Results provided strong indications that the 110 °C TL peak of quartz can be used effectively in the study of the bioactive behaviour of 58S bioactive glass, since it is unambiguously present in all samples and does not require deconvolution analysis. Furthermore, the intensity of the 110 °C TL peak is proven to be very sensitive to the different bioactive responses, identifying the loss of silica which takes place at the first stages of the sequence. The discontinuities of the 110 °C TL peak intensity plot versus immersion time at 8 and 1440 min provide experimental indications regarding the timescale for both the beginning of amorphous CaP formation as well as the end of crystalline hydroxyl-apatite formation respectively, while the spike in the sensitization of the 110 °C TL peak, which was observed for immersion times ranging between 20 and 40 min, could be an experimental feature indicating the beginning of the crystalline HCAp formation.