Prominent Thermoluminescence Glow Research Articles

Thermoluminescence mechanism of microwave combustion synthesized γ-irradiated Al2O3:Tm3+ phosphor

The thermoluminescence (TL) mechanism of γ-irradiated Al2O3:Tm3+ phosphor is presented in this paper. Al2O3:Tm3+ phosphors are synthesized by muffle furnace combustion (MFC) and microwave combustion (MWC). XRD results exhibit the stable alpha phase of Al2O3 and crystallite size is found to be ∼99 and ∼147 nm for MFC and MWC synthesized samples respectively. The optical band gap (Eg) of MFC and MWC synthesized Tm3+-doped materials is found to be 4.27 and 4.31 eV, respectively using DRS. TL glow curves of γ -irradiated Al2O3:Tm3+ phosphor are recorded for the dose ranging from 0.1 to 20 Gy. TL glow curves of γ - irradiated phosphor show a prominent peak at ∼453 K along with a shoulder at ∼500 K. The prominent TL glow peak (455 K) intensity of MWC synthesized Al2O3:Tm3+ is ∼2.56 times higher than MFC synthesized phosphor. The TL emission spectra of 455 K glow peak show emission at 298, 355, 394, 466, 526, and 658 nm corresponding to the 1I6→3H6, 1D2→3H6, 3P2→3H4, 1G4→3H6, 1D2→3H5 and 1D2→3H4 characteristic transitions of Tm3+. TL emission spectrum exhibits Cr3+ (R-lines) and Mn4+ characteristic emission peaks at 453 K along with Tm3+ emission. TL intensity of the MWC synthesized sample's prominent peak at 453 K increases linearly with a dose from 0.1 to 15 Gy and then it increases super-linearly with a dose up to 20 Gy. The kinetic parameters were calculated and the process of ionization of electrons from Tm3+, electron trap in host lattice, and its recombination mechanism is proposed.

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

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

Structural and optical properties of beta irradiated YAlO3 single crystals

We report on the growth, structural and optical properties of YAlO3 single crystals grown by optical floating zone technique. Powder X-ray diffraction and Raman spectroscopic studies confirm the phase purity of the crystals. Raman analysis reveals that the intensity and line-width of Raman bands increase significantly with beta irradiation indicating the formation of structural defects in YAlO3 lattice. The optical properties are studied through UV–visible absorption, and photoluminescence emission and excitation spectroscopies under pre- and post- beta irradiation. The optical studies indicate the presence of Sm and Cr impurities by exhibiting characteristic emission lines in the orange red region. Further, a systematic study on the thermoluminescence (TL) characteristics of the crystal is also carried out at different doses of beta irradiation. The crystals exhibit a prominent TL glow peak at 239 °C for less than 5 Gy doses while a weak second glow peak evolves at higher doses. Also, the crystals show a nearly linear dose response in the studied range from 0.1 to 10 Gy. The glow curve analysis reveals that the TL emission obeys the first order kinetics model. Based on the optical studies, the plausible mechanism for the TL glow curve is discussed in terms of the intrinsic defects and impurities that are present in the crystal.

Harnessing the thermoluminescence of Ge-doped silica flat-fibres for medical dosimetry

Study has been made of key thermoluminescence (TL) properties of Ge-doped silica flat-fibre, including TL glow curves, dose-rate dependency and reproducibility, the fibres being photon irradiated over the dose range 0.5- to 8 Gy, use being made of a medical linear accelerator (LINAC) operated at either 6- or 10 MV. Percentage depth doses (PDD) were also studied, comparison being made of fibre-measured PDD values against those obtained using an ionization chamber and standard TLD-100 and TLD-700 chips. The flat-fibre samples displayed a single prominent TL glow curve dosimetry peak at 249 °C, the structure of this remaining unchanged during repeat cycles of annealing and irradiation at different doses. For fixed dose, the TL responses of the samples also remained practically constant in use of five different dose-rates in the range100 MU/min to 500 MU/min. The effective atomic number (Zeff) of the flat-fibre was calculated to be 13.37, greater than soft tissue (7.42) but within the range of values for human bone (11.6–13.8). Using the 6 MV photon beam, PDD studies yielded a dmax of 1.5 cm, consistent with the value attained using the ionization chamber and the standard TLD chips. At 2 cm depth, the optical fibre samples showed good agreement to within −4%, 1.3% and 4% respectively with measurements made in use of the ionization chamber, standard TLD-100 chips and TLD-700 chips. The study represents part of an overall plan towards development of silica fiber-based dosimeters for radiotherapy and diagnostic radiology applications.

Synthesis, thermoluminescence and defect centres in Eu3+ doped Y2O3 nanophosphor for gamma dosimetry applications

Europium doped Y2O3 nanophosphors have been prepared by the solution combustion method. The prepared nanophosphors were characterized by powder x-ray diffraction (XRD). XRD revealed that the cubic phase with crystallite size in the range 25–37 nm formed. Surface morphology of the samples was studied by field emission scanning electron microscopy and the particles were observed as spherical in nature, having an average size ~30 nm. The electron spin resonance spectrum of the irradiated nanophosphor exhibited a signal having peaks at g = 2.1646 and 2.0035 which are attributed to and defect centers, respectively. Thermoluminescence (TL) emission showed a strong red (611 nm) emission at 417 K. The prominent TL glow (417 K) peak exhibited low fading, good reproducibility and linear dose response in the range 0.01–2.0 kGy. This behavior is favorable for TL dosimetry applications. The Y2O3:Eu3+ nanophosphor has prodigious potential as a dosimeter to be use for monitoring high dose ionizing radiation fields.

Photoluminescence, thermoluminescence glow curve and emission characteristics of Y2O3:Er3 + nanophosphor

Nanocrystalline Er3+ doped Y2O3crystals were prepared by a sol gel technique. X-ray diffraction (XRD) patterns showed the cubic structure of Y2O3 and the crystallite size was found to be ~25nm. Optical absorption showed absorption peaks at 454, 495 and 521nm. These peaks are attributed to the 4F3/2+4F5/2, 4F7/2 and 2H11/2+4S3/2 transitions of Er3+. Under excitation at 378nm, the appearance of strong green (520–565nm) down conversion emission assigned to the (2H11/2,4S3/2)→4I15/2 transition and the feeble red (650–665nm) emission is assigned to the 4F9/2→4I15/2 transition. The color chromaticity coordinates showed emission in the green region. The strong green emission of Y2O3:Er3+ nanophosphor may be useful for applications in solid compact laser devices. Thermoluminescence (TL) studies of γ-irradiated Y2O3:Er3+ showed a prominent TL glow peak maximum at 383K along with a less intense shoulder peak at ~425K and a weak glow at 598K. TL emission peaks with maxima at 545, 490, 588 and 622nm for the doped sample were observed at a temperature of 383K and these emissions were due to defect related to the host material. TL kinetic parameters were calculated by a glow curve deconvolution (GCD) method and the obtained results are discussed in detail for their possible usage in high dose dosimetry.

Thermoluminescence kinetic features of Lithium Iodide (LiI) single crystal grown by vertical Bridgman technique

Single crystal of pure Lithium Iodide (LiI) has been grown from melt by using the vertical Bridgman technique. Thermoluminescence (TL) Measurements were carried out at 1 K/s following X-ray irradiation. The TL glow curve consists of a dominant peak at (peak-maximum Tm) 393 K and one low temperature peak of weaker intensity at 343 K. The order of kinetics (b), activation energy (E), and the frequency factor (S) for a prominent TL glow peak observed around 393 K for LiI crystals are reported for the first time. The peak shape analysis of the glow peak indicates the kinetics to be of the first order. The value of E is calculated using various standard methods such as initial rise (IR), whole glow peak (WGP), peak shape (PS), computerized glow curve deconvolution (CGCD) and Variable Heating rate (VHR) methods. An average value of 1.06 eV is obtained in this case. In order to validate the obtained parameters, numerically integrated TL glow curve has been generated using experimentally determined kinetic parameters. The effective atomic number (Zeff) for this material was determined and found to be 52. X-ray induced emission spectra of pure LiI single crystal are studied at room temperature and it is found that the sample exhibit sharp emission at 457 nm and broad emission at 650 nm.

Thermoluminescence response of 120 MeV Ag9+ and γ-ray exposed LiMgBO3:Dy3+ nanophosphors for dosimetry

Thermoluminescence(TL) response of LiMgBO3:Dy3+ nanophosphor synthesized by combustion method was examined using γ-ray and 120MeV Ag9+ swift heavy ion (SHI) irradiation. The LiMgBO3:Dy3+ samples were exposed to 0.01 kGy −5 kGy γ-rays while for the different fluences the samples were irradiated with 120MeV Ag9+ SHI over the range 1×1011ionscm−2 to 1×1013ionscm−2. The prominent TL glow curve peaks appeared at 396K and 390K for the γ-ray and 120MeV Ag9+ SHI irradiated samples. The glow curves for the SHI iradiated samples were more complex than those of the γ-ray exposed samples. The effect of different heating rates on the TL response was also determined. The trapping parameters (i.e. activation energy, frequency factor, order of kinetic) of all the individual peaks of the glow curves have been analysed by using Chen's formulae. The TL response curve against γ-ray exposure illustrated a good linear response upto 3 kGy and after that the response was sublinear. For the 120MeV Ag9+ ion irradiated samples, the material exhibited a sublinear dependence against ion irradiation for the studied fluence. The good TL response against γ-ray irradiation suggested that the material can be explored for a possible application in dosimetry.

Luminescence properties of La2O3:Eu3+ nanophosphor prepared by sol–gel method

Undoped and Eu3+ doped La2O3 nanophosphor are synthesized by low temperature sol–gel technique. The synthesized samples are characterized by X-ray diffraction (XRD) and average crystallite size is found to be ∼18nm and ∼23nm for undoped and Eu3+ doped La2O3 respectively. Gamma ray irradiated undoped La2O3 shows high intense thermoluminescence (TL) glow peak at 640K and weak TL glow peak at 443K and the high intense peak intensity is sub linear increase with γ-dose. Whereas Eu3+ doped La2O3 nanophosphor show a prominent TL glow peak at 640K and its TL intensity linearly increases up to 1kGy. The kinetic parameters are estimated using glow curve deconvoluted (GCD) technique. TL emission of γ-ray irradiated Eu3+ doped La2O3 show peaks at 508, 586, 619 and 706nm are attributed to Eu3+ transition peaks.

Thermoluminescence properties of gamma irradiated CaO: Sm3+ phosphor

Pure and samarium doped calcium oxide (CaO) is synthesized by solution combustion technique. The samples are annealed at 600°C for two hours. X-ray diffraction (XRD) pattern of the annealed sample show cubic phase with space group Fm3m. The average crystallite size is found to be ∼54nm. Fourier transform infra red (FTIR) spectrum exhibits bands at 424, 544cm−1 (Ca–O bond), 875cm−1 (C–O bond), 1460cm−1 (C–O stretch) and 3640cm−1 (O–H stretch). The samples are irradiated with gamma rays in a dose range 100–4000Gy. Thermoluminescence (TL) glow curves are recorded at a linear heating rate (β) of 5Ks−1. A prominent TL glow with a peak at 636K is observed in undoped sample. A new TL glow with peak at ∼458K is observed in addition to 636K in samarium doped (1mol%) CaO. TL glow peak intensity (Imax) at 636K increases with γ – dose in the study range. TL emissions at 560, 600 and 640nm are observed in doped samples corresponding to Sm3+ transitions along with pristine emissions. TL glow curves are deconvoluted to obtain kinetic parameters. The mean value of activation energy and the frequency factor of the prominent deconvoluted TL glow peak (626K) are found to be 1.26eV and 4.49×109s−1 respectively.

Synthesis characterization and luminescence studies of gamma irradiated nanocrystalline yttrium oxide

Nanocrystalline Y2O3 is synthesized by solution combustion technique using urea and glycine as fuels. X-ray diffraction (XRD) pattern of as prepared sample shows amorphous nature while annealed samples show cubic nature. The average crystallite size is calculated using Scherrer's formula and is found to be in the range 14–30nm for samples synthesized using urea and 15–20nm for samples synthesized using glycine respectively. Field emission scanning electron microscopy (FE-SEM) image of 1173K annealed Y2O3 samples show well separated spherical shape particles and the average particle size is found to be in the range 28–35nm. Fourier transformed infrared (FTIR) and Raman spectroscopy reveals a stretching of Y–O bond. Electron spin resonance (ESR) shows V− center, O2− and Y2+ defects. A broad photoluminescence (PL) emission with peak at ~386nm is observed when the sample is excited with 252nm. Thermoluminescence (TL) properties of γ-irradiated Y2O3 nanopowder are studied at a heating rate of 5Ks−1. The samples prepared by using urea show a prominent and well resolved peak at ~383K and a weak one at ~570K. It is also found that TL glow peak intensity (Im1) at ~383K increases with increase in γ-dose up to ~6.0kGy and then decreases with increase in dose. However, glycine used Y2O3 shows a prominent TL glow with peaks at 396K and 590K. Among the fuels, urea used Y2O3 shows simple and well resolved TL glows. This might be due to fuel and hence particle size effect. The kinetic parameters are calculated by Chen's glow curve peak shape method and results are discussed in detail.

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.

Thermoluminescence of sol–gel derived Y2O3:Nd3+ nanophosphor exposed to 100 MeV Si8+ ions and gamma rays

Nanocrystalline Nd3+ doped Y2O3 was synthesized by sol–gel technique. Crystallite size calculated by Scherrer relation was found to be in the range 28–30nm. Fourier transform infrared spectroscopy (FTIR) revealed YO, OH stretching and CO bending bonds. Pellets of Y2O3:Nd3+ were irradiated with 100MeV swift Si8+ ions and γ-rays for the fluence/dose in the range 3×1011–3×1013ionscm−2 and 1.0_14kGy respectively. A prominent thermoluminescence (TL) glow with peak at 527K and a weak one with peak at 600K were observed in Si8+ ion irradiated samples while, a prominent TL glow with peak at 393K besides a shoulder at 434K and a weak one with peak at 581K were observed in γ-irradiated phosphors. The relative TL efficiency of Y2O3:Nd3+ of 100MeV Si ion beam to γ-rays of 60Co and is found to be 0.059. The TL kinetic parameters were calculated using Chen’s peak shape method and the results obtained are discussed. Y2O3:Nd3+ was observed for its use in space dosimetry application.

Thermoluminescence response of CaS:Bi 3+ nanophosphor exposed to 200 MeV Ag +15 ion beam

A study of the thermoluminescence (TL) parameters has been performed on swift heavy ion exposed Bi 3+ doped CaS nanophosphors prepared by the chemical co-precipitation method. All the samples have been exposed to 200 MeV Ag +15 ions in a fluence range of 1 × 10 12–1 × 10 13 ions/cm 2. The prominent TL glow peak at 403 K (observed for the γ-irradiated sample) appeared at the same position in the 200 MeV Ag +15 ion beam irradiated samples, while the other peak at 466 K disappeared and the broad peak normally measured at 534 K split into two peaks at 535 K and 582 K for the Ag +15 ion beam irradiated samples. The effect of different Bi 3+ concentration has been investigated and it was found that the maximum TL intensity was measured for the 0.08 mol% sample. The effect of different heating rates on the TL response has also been determined. The trapping parameters (i.e. activation energy, frequency factor, order of kinetic) of all the individual peaks of the glow curves have been analysed by using Chen’s formulae. The low fading and linear TL response in the range of 1 × 10 12–1 × 10 13 ions/cm 2 will be helpful to explore the potential use of this material for heavy ion dosimetry.

K3Na(SO4)2 : Eu nanoparticles for high dose of ionizing radiation

K3Na(SO4)2 : Eu nanocrystalline powder was synthesized by the chemical co-precipitation method. The x-ray diffraction pattern of the nanomaterials shows a hexagonal structure for its crystals having grain size of ∼28 nm. Transmission electron microscopy revealed that the K3Na(SO4)2 : Eu nanoparticles are single crystals with almost a uniform shape and size. Thermoluminescence (TL) was taken after irradiating the samples at various exposures of γ-rays from a 60Co source. A prominent TL glow peak is observed at 423 K along with three small peaks/shoulders at around 382, 460 and 509 K. The observed TL sensitivity of the prepared nanocrystalline powder is around 4 times more than that of LiF : Mg,Ti (TLD-100) phosphor. The 423 K peak of the nanomaterial phosphor eventually shows a near linear response with exposures increasing up to very high values (as high as 70 kGy), where all the other TLD phosphors saturate. This property along with its other desired properties such as high sensitivity, relatively simple glow curve structure and low fading makes the nanocrystalline phosphor a suitable dosimeter to estimate low as well as high exposures of γ-rays. TL analysis using the glow curve deconvolution technique was also done for determining different trapping parameters.

Thermoluminescence and ESR in an aragonite speleothem

Mechanisms of thermoluminescence (TL) in aragonite have been studied using electron spin resonance (ESR) techniques. Natural aragonite shows a prominent TL glow peak at 613 K. Additional gamma irradiation enhanced this glow peak but displaces it slightly to 593 K, and induces two glow peaks at 393 and 493 K. Pre-annealing at 653 K for 10 min and subsequent gamma irradiation also induces and enhances two glow peaks at 393 and 493 K. The authors show that second-order kinetics characterizes all the glow peaks reasonably well. Results of dose calibration in aragonite indicate that the 393 K peak increases linearly with dose, whereas the others exhibit anomalous behaviours. On the other hand, aragonite presents a complex ESR spectrum. The pre-anneal and subsequent irradiation procedure is found to enhance Pb3+ and CO3- ESR hole centres. An isochronal thermal anneal sequence experiment indicates that these ESR centres can be related to two glow peaks at 393 and 493 K. A model for the recombination mechanism is suggested on the basis of TL and ESR measurements.

Radiation induced traps of zinc phosphate and phosphide

Thermoluminescence (TL) glow curve (TGC) method has been used to study the traps produced by X-irradiation in Zn 3(PO 4) 2 and Zn 3P 2. Prominent TL glow peaks were observed at 100° and 360°C for Zinc phosphate while for Zinc phosphide only one glow peak at 245°C was observed, and in the latter case the TL output was in general quite low compared to Zinc phosphate. The TL spectra for both the glow peaks of Zinc phosphate indicated emission band in the region around 560 nm, while for Zinc phosphide the emission occured at 575 nm (in the temperature region 200–270°C). The low temperature glow peaks below 270°C were less stable compared to those above 300°C and were completely destroyed when the irradiated samples were stored in darkness for 24 hr at room temperature. Shinning by 470 nm light however produced preferential bleaching of the two TL peaks at 100 and 360°C with no effect on the 245°C glow peak of Zinc phosphide. It is concluded that during heat treatment large numbers of Zn-vanancies are formed due to which complexes like ZnO and ZnP are produced by irradiation and the TL traps destroyed in a radiative recombination process are related with these complexes.