Prominent Glow Peak Research Articles

Thermoluminescence in β-irradiated SrZnF4:Dy TLD phosphor

SrZnF4:Dy phosphor was prepared by the wet chemical synthesis and characterized for its X-ray diffraction, thermoluminescence (TL) and photoluminescence (PL) properties. The PL emission spectra for SrZnF4:Dy3+ phosphor at 351 nm excitation give emission at 481 nm (blue) and 575 nm (yellow). The TL properties of SrZnF4:Dy were studied using β-irradiation. The response curve of the prepared phosphor with high-dose β-ray exposure is linear as compared with well-known CaSO4:Dy phosphor. The TL glow curves of SrZnF4:Dy sample showed two well-defined peaks at 143°C (peak-1) and 231°C (peak-2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameter associated with the prominent glow peaks of SrZnF4:Dy is calculated by using Chen's method.

Evaluation of trapping parameters in KCaSO4Cl: X (X=Ce, Dy, Mn or Pb) phosphor by TL

Polycrystalline KCaSO4Cl: (Ce, Dy, Mn and Pb) phosphors prepared by solid state diffusion method have been studied for its trapping parameters by thermoluminescence (TL) phenomenon. The TL glow curves of KCaSO4Cl: (Ce, Dy, Mn and Pb) phosphor for different concentrations have been recorded at a heating rate of 2°Csec−1 and irradiated at a dose rate of 0.995kGyh−1 for 5Gy. The TL glow curves of γ-irradiated KCaSO4Cl: (Ce, Dy, Mn and Pb) phosphors show one glow peak indicating that only one set of traps is being activated within the particular temperature range each with its own value of activation energy (E) and frequency factor (s). The trapping parameters associated with the prominent glow peak of KCaSO4Cl: (Ce, Dy, Mn and Pb) is calculated by using Chen's half width method. The phosphors KCaSO4Cl: Ce, and Pb show first order kinetics while, Dy and Mn show the second order kinetics. The trap depth and frequency factors have been studied subsequently. The release of hole or electron from defect centers at the characteristic trap site initiates the luminescence process in this material.

Photoluminescence and thermoluminescence studies of Tb3+ doped ZnO nanorods

Abstract Here in, the synthesis of the terbium doped zinc oxide (ZnO:Tb3+) nanorods via room temperature chemical co-precipitation was explored and their structural, photoluminescence (PL) and thermoluminescence (TL) studies were investigated in detail. The present samples were found to have pure hexagonal wurtzite crystal structure. The as obtained samples were broadly composed of nanoflakes while the highly crystalline nanorods have been formed due to low temperature annealing of the as synthesized samples. The diameters of the nanoflakes are found to be in the range 50–60 nm whereas the nanorods have diameter 60–90 nm and length 700–900 nm. FTIR study shows Zn O stretching band at 475 cm−1 showing improved crystal quality with annealing. The bands at 1545 and 1431 cm−1 are attributed to asymmetric and symmetric C O stretching vibration modes. The diffuse reflectance spectra show band edge emission near 390 nm and a blue shift of the absorption edge with higher concentration of Tb doping. The PL spectra of the Tb3+-doped sample exhibited bright bluish green and green emissions at 490 nm (5D4 → 7F6) and 544 nm (5D4 → 7F5) respectively which is much more intense then the blue (450 nm), bluish green (472 nm) and broad green emission (532 nm) for the undoped sample. An efficient energy transfer process from ZnO host to Tb3+ is observed in PL emission and excitation spectra of Tb3+-doped ZnO ions. The doped sample exhibits a strong TL glow peak at 255 °C compared to the prominent glow peak at 190 °C for the undoped sample. The higher temperature peaks are found to obey first order kinetics whereas the lower temperature peaks obey 2nd order kinetics. The glow peak at 255 °C for the Tb3+ doped sample has an activation energy 0.98 eV and frequency factor 2.77 × 108 s−1.

Synthesis, characterization and studies of radiative properties on Eu3+-doped ZnAl2O4

Eu3+-doped ZnAl2O4 phosphors were successfully synthesized in air atmosphere at 900°C. The phosphors were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermally stimulated luminescence (TSL) and photoluminescence (PL) techniques. The average particle size of the system as determined from SEM was found to be 100–150nm (for samples annealed at 900°C). PL spectra of the doped phosphors showed emission peaks corresponding to Eu3+ ions. Lifetime studies revealed Eu3+ ions to be in two different sites. The asymmetric ratio (I616/I592) was observed to be about 3.75. This suggested that Eu3+ ion entered the host mainly substituting Al3+ site distorting the local environment and is partly located on surface of the phosphors. A prominent glow peak at 430K was observed in the TSL of γ-irradiated Eu3+-doped ZnAl2O4 phosphors. Trap parameters for this peak have been determined and the probable mechanism for the glow peak is proposed. CIE chromaticity coordinates for the system were evaluated. It was observed that, the system could be employed as a potential red emitting phosphor. Commercial utility of the phosphor was investigated by comparing it with commercial red phosphor. The PL intensity of the as prepared phosphors was 63% of that of the commercial phosphor. Apart from this, various radiative properties such as the Judd–Ofelt intensity parameters, spontaneous emission probabilities, luminescence branching ratios, radiative lifetimes and quantum efficiency were evaluated for the system.

Cu+ emission in Li2BPO5 material for thermoluminescence dosimetry

In this study, Li2BPO5 doped with Cu and that co-doped with Mg are synthesized by the wet chemical technique and exposed to γ rays of 60Co to determine their thermoluminescence (TL) properties. The X-ray diffraction technique shows the crystalline nature of the prepared material. The photoluminescence (PL) emission spectra of Li2BPO5:Cu phosphor show the strong prominent peak at 368 nm in the violet region of the visible spectrum due to the transition of 3d94s1 ↔ 3d10 of monovalent copper ion. The PL emission of Li2BPO5:Cu is enhanced by the addition of Mg. The TL glow curves of γ-irradiated Li2BPO5:Cu sample show one glow peak at 143°C, indicating that only one set of traps is being activated within the particular temperature range each with its own value of activation energy (E) and frequency factor (s). The trapping parameters associated with the prominent glow peak of Li2BPO5:Cu are calculated using the glow curve shape (Chen's) method. The release of hole/electron from defect centers at the characteristic trap site initiates the luminescence process in these materials. A linear TL response is observed in Li2BPO5:Cu in a long span of exposures. The sensitivity of Li2BPO5:Cu sample is observed to be 7.8 times that of (TLD-100) LiF:Mg, Ti.

Luminescence investigations on sulfate apatite Na 6(SO 4) 2FCl:RE (RE=Dy, Ce or Eu) phosphors

A new phosphor in the Cl–F system doped with Dy, Ce and Eu has been reported. Characterization of this phosphor using XRD, PL and TL techniques is described. Polycrystalline Na 6(SO 4) 2FCl:Dy; Na 6(SO 4) 2FCl:Ce and Na 6(SO 4) 2FCl:Eu phosphors prepared by a solid state diffusion method have been studied for their X-ray diffraction, photoluminescence (PL) and thermoluminescence (TL)characteristics. The PL excitation and emission spectra of phosphors were obtained. Dy 3+ emission in the host at 475 and 570 nm is observed due to 4F 9/2→ 6H 15/2 and 4F 9/2→ 6H 13/2 transition, respectively, whereas the PL emission spectra of Na 6(SO 4) 2FCl:Ce phosphor shows the Ce 3+ emission at 322 nm due to 5d→4f transition of Ce 3+ ion. In Na 6(SO 4) 2FCl:Eu lattice, Eu 2+ as well as Eu 3+ emissions are observed. The emission of europium ion in this compound exhibits the blue as well as red emission. The TL glow curves of the same compounds have the simple structure with a prominent peak at 150, 175 and 200 °C. TL response, fading, reusability and trapping parameters of the phosphors are also studied. The TL glow curves of γ-irradiated Na 6(SO 4) 2FCl sample show one glow peak indicating that only one set of traps is being activated within the particular temperature range each with its own value of activation energy ( E) and frequency factor ( s). The trapping parameters associated with the prominent glow peak are calculated using Chen’s half width method. The release of hole/electron from defect centers at the characteristic trap site initiates the luminescence process in these materials. The intensity of the TL glow peaks increases with increase of the added γ-ray dose to the samples.

Effect of ion irradiation on the thermoluminescence properties of K2Ca2(SO4)3 phosphor

This paper presents the thermoluminescence (TL) studies of ion-irradiated potassium–calcium mixed sulfate phosphor. The sample was prepared by the solid-state diffusion method. The X-ray diffraction study of the prepared sample suggests an orthorhombic structure with an average particle size of 0.16 μ m. The samples were irradiated with 1.2 MeV argon ions at fluences varying between 1011 and 1015 ions/cm2. The argon ions penetrate to a depth of 1.93 μ m and lose their energy mainly via electronic stopping. Due to ion irradiation, a large number of defects such as oxygen vacancies, radicals and color centers are formed in the sample. TL glow curves were recorded for each of the ion fluences. A linear increase in the intensity of TL glow peaks was found with an increase in the ion dose from 72 kGy to 720 MGy. The kinetic parameters associated with the prominent glow peaks were calculated using glow curve deconvolution, different glow curve shapes and sample heating rate methods.

Argon ions induced thermoluminescence properties of Ba 0.12Sr 0.88SO 4 phosphor

Thermoluminescence properties of barium strontium mixed sulfate have been studied by irradiation with Argon ions. The sample was recrystallized by chemical co-precipitation techniques using H 2SO 4. The X-ray diffraction study of prepared sample suggests the orthorhombic structure with average grain size of 60 nm. The samples were irradiated with 1.2 MeV Argon ions at fluences varying between 10 11 and 10 15 ions/cm 2. The argon ions penetrate to the depth of 1.89 μm and lose their energy mainly via electronic stopping. Due to ion irradiation, a large number of defects in the sample are formed. Thermally stimulated luminescence (TSL) glow curves of ion irradiated Ba 0.12Sr 0.88SO 4 phosphor exhibit broad peak with maximum intensity at 495 K composed of four overlapping peaks. This indicates that different sets of traps are being activated within the particular temperature range each with its own value of activation energy ( E) and frequency factor ( s). Thermoluminescence (TL) glow curves were recorded for each of the ion fluences. A linear increase in intensity of TL glow peaks was found with the increase in ion dose from 59 kGy to 5.9 MGy. The kinetic parameters associated with the prominent glow peaks were calculated using glow curve deconvolution (GCD), different glow curve shape and sample heating rate methods.

Calculation for the trapping parameters of K 3Na(SO 4) 2 phosphor by isothermal luminescence decay method

In this paper thermally stimulated luminescence (TSL) studies of K 3Na(SO 4) 2 phosphor are reported. A polycrystalline sample of K 3Na(SO 4) 2 was prepared by the solid state diffusion method. Formation of compound was checked by use of XRD and Fourier-transform infrared (FTIR) spectroscopy. The TSL glow curves of X-irradiated K 3Na(SO 4) 2 sample show one glow peak at temperature 170 °C indicating that only one set of traps is being activated within the particular temperature range each with its own value of activation energy ( E) and frequency factor ( s). The trapping parameters associated with the prominent glow peak of K 3Na(SO 4) 2 are calculated by using isothermal decay method. The release of hole/electron from defect centers at the characteristic trap site initiates the luminescence process in these materials. The intensity of the TL glow peaks increases with increase of the X-ray dose to the sample.

Study of kinetic parameters of K 2Ca 2(SO 4)3 thermoluminescence dosimeter

The dosimetry study of thermoluminescence materials is based on a good knowledge of its kinetics para-meters. A polycrystalline sample of K 2Ca 2(SO 4)3 was prepared by the solid-state diffusion method. Formation of the compound was checked by using X-ray diffraction and Fourier-transform infrared spectroscopy. Thermally stimulated luminescence (TSL) glow curves of X-ray-irradiated K 2Ca 2(SO 4)3 phosphor exhibit one glow peak at 195 °C and a shoulder at around 120 °C, indicating that two different sets of traps are being activated within the particular temperature range, each with its own value of activation energy (E) and frequency factor (s). The kinetic parameters associated with the prominent glow peak of K 2Ca 2(SO 4)3 were calculated using the isothermal luminescence decay method. The electron spin resonance study of the prepared compound exhibits the presence of and radical ions that are responsible for the observed TSL glow peaks. The release of hole/electron from trap centres at the characteristic trap site initiates the luminescence process in these materials.

Thermoluminescence investigations in X-ray irradiated CaS phosphor

We report the thermoluminescence studies of X-ray irradiated CaS phosphor. The CaS phosphor was prepared by solid-state diffusion method and characterized by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Thermally stimulated luminescence (TSL) glow curves of X-ray irradiated CaS sample have two glow peaks at temperatures 100 and 130 °C. A reliable dosimetric study of a thermoluminescence material is based on good knowledge of its trapping parameters. The trapping parameters namely activation energy, order of kinetics and frequency factor associated with the prominent glow peak (130 °C) of CaS phosphor were calculated by using isothermal decay and glow curve shape (Chen's) methods.

Determination of trapping parameters from thermally stimulated luminescence glow curves of Mn-doped Li2B4O7 phosphor

The determination of trapping parameters such as order of kinetics, activation energy and frequency factor is one of the most important studies in the field of thermally stimulated luminescence (TSL). A polycrystalline sample of Mn-doped Li2B4O7 was prepared by melting method. The formation of the doped compound was checked by Fourier transform infrared study. The TSL study of the Mn-doped lithium tetraborate sample shows two glow peaks at 190 °C and 310 °C, of which the intensity of the 310 °C glow peak is the maximum. In this paper, the trapping parameters associated with the prominent glow peak of Mn-doped lithium tetraborate were reported using the isothermal luminescence decay and glow curve shape (Chen's) methods. Our results show a very good agreement between the trapping parameters calculated by the two methods.

Luminescence Studies of Pr3+ Doped Chitosan Biocomposite Matrix through UV Radiation Induced Thermal Stimulation

Thermoluminescence of Pr3+ doped chitosan biocomposite matrix (CBM) has been investigated. The polycrystalline sample of the matrix was prepared by the conventional solid-state reaction method. The formation of calcium sulfide in this process is checked for crystallization and phase by X-ray diffraction study, and the sample is found to have a rock salt structure at room temperature. Thermally stimulated luminescence studies of the matrix sample irradiated by a UV source show one prominent glow peak around 492.7 K and a shoulder peak around 370 K when heated with a linear heating rate of 2°C/s. The two glow peaks were isolated via thermal cleaning and a detailed kinetic analysis has been performed by various methods of determining the trap parameters, namely, order of kinetics (b), activation energy (E), and frequency factor (s) associated with both peaks of the CBM:Pr3+ matrix. A critical survey of the methods of determining E in our sample is undertaken to extend the domain of application as far as possible. We comment on the comparison between the derived parameter values and the correct values. From these comparisons we attempt to obtain some useful insights to assist in the interpretation of experimentally observed thermoluminescence spectra.

Thermoluminescence studies in swift heavy ion irradiated aluminum oxide

Thermoluminescence (TL) of combustion-synthesized aluminum oxide bombarded with 120 MeV swift Au 9 + ions in the fluence range of 1 × 10 11 - 2 × 10 13 ions cm - 2 has been studied at room temperature. Two TL glows—a well-resolved one with peak at ∼ 623 K ( Tg 2 ) and another unresolved one at ∼ 513 K (Tg1)—are recorded at a heating rate of 10 K s - 1 . It is found that the TL intensity increases with the fluence up to 1 × 10 13 ions cm - 2 and then decreases with increase in fluence. Also, the prominent glow peak temperature ( Tg 2 ) is found to be shifted towards the lower temperature region, while the TL intensity increases with the increase in ion fluence. In the case of heat-treated samples, the TL intensity is observed to be enhanced further. However, in the case of samples heat-treated beyond 973 K, the TL intensity is found to be decreased with the increase in heat treatment. The glow curves are analyzed by the glow curve deconvolution technique and trap parameters are estimated and discussed in this paper.

Thermoluminescence of undoped and Ce-doped BaB 4O 7

In this paper, the TL dosimetric characteristics of undoped and Ce-doped BaB 4O 7 compounds are reported. The polycrystalline powder samples were prepared by a melting method and the formation of the compounds were confirmed by an X-ray diffraction study. The TSL studies of undoped BaB 4O 7 sample show a prominent glow peak at 195 °C and three small peaks at 117, 255 and 365 °C whereas Ce-doped sample show three prominent TL glow peaks at 195, 250, 331 °C and two small peaks at around 90 and 135 °C when heated at a constant heating rate of 1 °C/s. Comparative TSL studies of these two compounds show that the Ce-doped BaB 4O 7 compound is approximately five times more sensitive than undoped compound. The TL emission spectra of Ce-doped showed a maxima at 360 nm for all measurements during TL measurements which is attributed to the characteristic emission from 5d to 4f transitions of Ce 3+ ion. The main dosimetric characteristics, which are namely the TL dose response, TL sensitivity, fading, minimum detectable dose, reproducibility, precision of dose measurement and annealing procedure, were shown that Ce-doped BaB 4O 7 sample could be used in dosimetric applications. The trap parameters namely order of kinetics ( b), activation energy ( E) and frequency factor ( s) associated with the glow peaks in β-irradiated undoped and Ce-doped barium borate samples were also obtained by computer glow curve deconvolution (CGCD) method.

Thermally stimulated luminescence studies of BaB4O7compound

In this paper thermally stimulated luminescence (TSL) studies of BaB4O7 compound are reported for the first time. The polycrystalline sample of BaB4O7 was prepared by a melting method and the formation of the BaB4O7 compound was confirmed by an X-ray diffraction study. The compound has orthorhombic structure at room temperature. The TSL glow curves of BaB4O7 compound when heated at a constant heating rate of 4°C/s exhibit two thermoluminescence (TL) glow peaks at 110 and 150°C followed by a shoulder around 210°C. The trapping parameters associated with the prominent glow peak of BaB4O7 are reported using isothermal luminescence decay method (ILDM). As a check the trap parameters are also calculated by glow curve shape (Chen's) method after isolating the prominent glow peak by thermal cleaning technique. Our results show a very good agreement between the trapping parameters calculated by the two methods.

Evaluation of trapping parameters of thermally stimulated luminescence glow curves in Cu-doped Li 2B 4O 7 phosphor

Evaluation of trapping parameters, including order of kinetics, activation energy and frequency factor, is one of the most important aspect of studies in the field of thermally stimulated luminescence (TSL). A polycrystalline sample of Cu-doped Li 2B 4O 7 was prepared by the melting method. Formation of the doped compound was checked by use of Fourier-transform infrared (FTIR) spectroscopy. TSL studies of the Cu-doped lithium tetraborate sample shows three glow peaks, the maximum emission occurring, respectively, at a temperature of 175°C, 290°C and 350°C, the intensity of the 175°C-glow peak being the maximum. The trapping parameters associated with this prominent glow peak of Cu-doped lithium tetraborate are reported herein, using the isothermal luminescence decay and glow curve shape (Chen's) methods. Our results show very good agreement between the trapping parameters calculated by the two methods.

Thermoluminescence and photoluminescence characteristics of sol–gel prepared pure and europium doped silica glasses

Thermoluminescence (TL) and photoluminescence (PL) measurements have been performed on gamma-irradiated amorphous SiO2 and SiO2 : Eu glass samples prepared by the sol–gel technique. In this type of silica the basic TL feature i.e. a prominent glow peak at 60 < Tm < 120°C is similar to that already studied in several such amorphous SiO2 samples. The temperature of the glow peak also shifts to higher values as a result of partial pre-heating treatments as has been reported earlier for other silica glasses. In the europium doped silica a prominent TL peak is obtained at around 170°C with a small shoulder at around 115°C. Significantly, a partial pre-heating for even up to 100°C simply removes the 170°C peak from the glow curve and a new peak of very low intensity is found above 300°C. An explanation for such strange results has been provided in this paper. Moreover, PL studies performed on the europium doped material show the presence of europium as both Eu2+ and Eu3+ in the material.

Thermoluminescence of Tb doped Gd 2O 2S phosphor

Thermoluminescence (TL) of gadolinium oxysulfide activated with terbium (Gd 2O 2S:Tb) is investigated. The glow curves of Gd 2O 2S:Tb phosphor recorded in the temperature range of 93–500 K with a heating rate of 0.52 K s −1 shows five prominent glow peaks. Comparison of the glow curves exhibited by different samples prepared with varying firing conditions reveals some interesting results. In this phosphor capture centers are mainly formed due to variable valency activators, trace impurities and point defects, which create defects in the sub-lattice. The observed TL spectra suggest a multiplicity of electron and hole traps. The main peak that observed at 150 K is attributed to point defects arising out of sulfur vacancies. These vacancies give rise to electron traps, which are found to be associated with terbium centers. This is confirmed by the monochromatic glow curves observed at wavelengths corresponding to the characteristic terbium emission ( 5 D 3 – 7 F n , 5 D 4 – 7 F n ). Removal of this glow peak under H 2S firing indicates the localized character of the concerned centers.

Thermoluminescence of Photostimulable Materials after X Irradiation below Room Temperature

Thermoluminescence glow peaks in the temperature range 100 to 400 K are investigated for BaFX (X = Cl, Br) crystals after X irradiation at 100 K. A prominent glow peak of BaFCl around 210 K is found to be composed of a few recombination roots, that is, the peak corresponds to the recombination of hole trapped centres such as an O- centre and a dissociated Cl2- centre with the F (F-) centre and the O2--F(Cl-) pair defect. Another small glow peak around 270 K is likely to occur from thermal dissociation of the O2- -F(Cl-) pair defect. The main glow peak of BaFBr:O2- at 170 K may be attributed to a recombination of an O- centre with the F(Br-) centre.