Thermally Stimulated Luminescence Spectra Research Articles

Thermally Stimulated Luminescence and Photoluminescence Properties of Dy-Doped Al2O3-SiO2 Glasses

Storage-type phosphors absorb and temporarily store the energy of ionizing radiation and emit low-energy photons when an external stimulus such as heat or light is applied. Since the number of emitted photons is proportional to the energy of the absorbed ionizing radiation, it is possible to estimate the irradiated dose. For this reason, they are applied in various fields such as personal radiation dosimetry and medical imaging. Storage-type phosphors are classified according to the type of external stimulus applied: optically stimulated luminescence (OSL) and thermally stimulated luminescence (TSL) materials. The mechanisms of OSL and TSL can be explained below. When a storage-type phosphor is irradiated with ionizing radiation, a large number of carriers are generated, and these carriers are trapped in the trapping centers in the material, which assumes a metastable state. Subsequent stimulation with heat or light causes the carriers to be re-excited, resulting in luminescence. These storage-type phosphors are required to have high emission intensity, wide dynamic range, and low fading. In particular, when applied to personal dosimeters, the materials must have tissue equivalency.Al2O3-SiO2 glasses focused on in this study have good characteristics such as high hardness, high melting point and elastic modulus, and low electric conductivity. Therefore, this glass composition has been considered for optical amplifiers and lasers. These properties are also advantageous in terms of material durability when used for dosimetry. In addition, the effective atomic number (Zeff = 11.8) of Al2O3-SiO2 glasses is close to that of human soft tissues, making it a promising storage-type phosphor for personal dosimeters. Therefore, the purpose of this study was to investigate the TSL properties of this glass system in detail and to evaluate the dose-response characteristics.We prepared the Dy-doped 10Al2O3-90SiO2 glasses with various Dy concentrations (0.1, 0.3, 1.0, and 3.0%) by the melt-quenching method and investigated the photoluminescence (PL) and TSL properties. We measured the TSL glow curves of all samples to research the concentration dependence of Dy. As a result, all samples showed the TSL at around 200℃, and the 0.3% Dy-doped 10Al2O3-90SiO2 glass showed the highest TSL intensity. It was found that the TSL originated from the 4f–4f transition of Dy3+ by measuring the TSL spectrum. In addition, the lower detection limit of the 0.3% Dy-doped sample was at least 0.1 mGy. Other details on optical, TSL, and these characteristics changes due to Dy concentration in the glass will be presented in our presentation.

Photoluminescence and thermally stimulated luminescence properties of Sr3Y(PO4)3 single crystals doped with dy

Sr3Y(PO4)3 (SYPO) is recognized as a highly promising material for dosimetry applications, owing to its dosimetric properties. In this work, we synthesized the SYPO single crystals doped with 0.1, 0.5, 1, and 5 % Dy using the floating zone furnace to evaluate the photoluminescence and thermally stimulated luminescence (TSL) characteristics. All the SYPO single crystals doped with Dy exhibited emission peaks at 480, 580, 670, and 760 nm in PL and TSL spectra. These emission peaks were typical for the 4f–4f transitions of Dy3+ ions. The SYPO single crystal doped with 0.1 % Dy displayed a glow peak in the TSL glow curve at 70 °C. The SYPO single crystals doped with 0.5, 1, and 5 % Dy showed two glow peaks at approximately 70 and 110 °C. The SYPO single crystal doped with 0.5 % Dy exhibited the highest TSL intensity with a lower detection limit of 0.1 mGy. The SYPO single crystal doped with 0.5 % Dy showed a spatial resolution of 50.0 μm after X-ray irradiation of 1Gy.

Thermally stimulated luminescence properties of Mn-doped MgAl2O4 translucent ceramics

MgAl2O4 translucent ceramics doped with Mn were fabricated by spark plasma sintering, and optical and dosimetric properties were evaluated. The 1% Mn-doped MgAl2O4 translucent ceramic exhibited a photoluminescence emission peak at 520 nm due to Mn2+. Thermally stimulated luminescence (TSL) glow peaks of the Mn-doped MgAl2O4 translucent ceramics were observed at around 60 and 260 °C. Moreover, the TSL intensity increased as the heating temperature rose to 490 °C. TSL spectra confirmed that Mn2+ had a role of recombination centers in the TSL process. The 0.01% Mn-doped MgAl2O4 translucent ceramic showed a proportional relationship between the TSL intensity and irradiation doses ranging from 0.1 to 1000 mGy.

New emission band of solid nitrogen

New results on the study of radiation effects in solid nitrogen and N2-doped Ne matrix are presented, with a focus on the so-called γ-line origin. The irradiation was carried out in dc regime with an electron beam of subthreshold energy. The relaxation dynamics was monitored by emission spectroscopy: cathodoluminescence (CL) and nonstationary luminescence (NsL), along with current activation spectroscopy. Thermally stimulated luminescence (TSL) and exoelectron emission (TSEE) of pure nitrogen and N2 in the Ne matrix were measured in a correlated manner. Three emission bands were recorded in the NIR CL spectra of solid N2: 794, 802, and 810 nm. The band at 810 nm was detected for the first time. These three bands are characterized by similar behavior and form molecular series with spacing between adjacent vibrational energy levels of the ground state of 125 and 123 cm−1. These data cast doubt on the recently made assumption that the γ-line is attributed to the emission of the nitrogen anion N− [R. E. Boltnev, I. B. Bykhalo, I. N. Krushinskaya et al. Phys. Chem. Chem. Phys. 18, 16013 (2016)]. The processes of electron attachment and neutralization of positively charged species are discussed. It has been established that the γ-line in the TSL spectra of pure nitrogen and N2-doped Ne matrix correlates with TSEE currents and recombination emission of O+, N2+, and N4+ ions, which indicates its connection with the neutralization reaction. The measurement of NsL supported this conclusion. A new possible assignment of the γ-line and its satellites to the emission of tetranitrogen N4 is discussed.

Dosimetric properties of Tm2O3-doped Ca2BO3Cl

In this work, we prepared Ca2BO3Cl with various amounts (0.1%–1.0%) of Tm2O3 by conventional solid-state reaction and investigated the dosimeter properties. Scintillation peaks at 370, 455, 470, and 650 nm that were derived from the 4f→4f transition of Tm3+ appeared in the X-ray induced scintillation spectra, and the highest scintillation intensity was detected from the 0.5% Tm2O3-doped Ca2BO3Cl. Furthermore, the Tm2O3-doped Ca2BO3Cl exhibited a thermally-stimulated luminescence (TSL) with a main glow peak at 300 °C, and the fabricated Tm2O3-doped Ca2BO3Cl exhibited a linear response in the 0.1–1000 mGy range. In addition, the TSL spectra confirmed that a final luminescence process for the TSL was the 4f→4f transition of Tm3+. In addition to TSL, optically-stimulated luminescence that was attributable to the 4f→4f transition of Tm3+ was recorded under 520 nm light, and the lowest detectable limit was about 1 mGy.

Photoluminescence, scintillation, and dosimetric properties of undoped and Tb-doped Ba3Gd(PO4)3 single crystals

Undoped and Tb-doped Ba3Gd(PO4)3 single crystals were synthesized by the floating zone method. Photoluminescence (PL), scintillation, and thermally stimulated luminescence (TSL) properties of the obtained single crystals were evaluated. The highest PL quantum yield value was obtained from the 5% Tb-doped single crystal. In X-ray-induced scintillation and TSL spectra, the undoped sample represented an emission peak originating from the 4f–4f transition of Gd3+ at 310 nm. The Tb-doped samples represented emission peaks originating from the 4f–4f transitions of Tb3+ and Gd3+ in the range of 310–620 nm. In TSL dose response functions, the 1% Tb-doped sample showed the highest TSL intensity, and the lower detection limit was 0.01 mGy.

Floating zone growth and evaluation of photoluminescence and dosimetric properties of undoped and Eu-doped Al4SiO8 single crystals

We fabricated undoped and 0.5, 1.0, 2.0, and 3.0% Eu-doped Al4SiO8 single crystals by the floating zone method and analyzed their photoluminescence (PL) and thermally stimulated luminescence (TSL) properties. In PL properties, the undoped sample exhibited an emission band at 460 nm under excitation wavelength at 260 nm. The Eu-doped samples showed an emission band at 410 nm attributed to the 5d-4f transitions of Eu2+ ions. In TSL properties, the undoped sample exhibited TSL glow peaks at 280 and 390 °C, while the Eu-doped samples showed the ones at 230 and 370 °C. The TSL spectra of the Eu-doped samples under heating at 230 °C had an emission band due to the 5d-4f transitions of Eu2+ ions. TSL dose response functions showed a lower detection limit of 10 mGy for the undoped sample, 10 μGy for the 0.5% Eu-doped sample, and 1 μGy for the 1.0, 2.0, and 3.0% Eu-doped samples. The TSL intensity of the 2.0% Eu-doped sample was approximately 72.6% after 11 days from X-ray irradiation compared to immediately after X-ray irradiation.

Dosimetric properties of MgAl2O4 transparent ceramics doped with Ce

Ce-doped MgAl2O4 transparent ceramics were fabricated by the spark plasma sintering method. The 0.01% Ce-doped MgAl2O4 exhibited photoluminescence (PL) peaking at 410 nm upon the excitation of 310 nm. On the other hand, the 0.1%, 0.5%, and 1% Ce-doped MgAl2O4 showed different PL excitation peaks. The PL peak at 410 nm was attributed to 5d-4f transitions of Ce3+ ions with a decay time of a few nanoseconds. Thermally stimulated luminescence (TSL) glow curves were mainly composed of three glow peaks. When Ce-doped MgAl2O4 was heated at 300 °C, three TSL emission peaks were observed at around 410, 520 and 700 nm in TSL spectra, originating from Ce3+ ions, Mn2+ impurities, and Mg2+ vacancies, respectively. The normalized TSL intensity declined to 95% for the first 24 h and did not change in 1–5 d within the measurement error. The minimum detectable dose of the 0.5% Ce-doped MgAl2O4 was 0.5 μGy.

Ce-doping effect on dosimetric properties of mullite single crystals synthesized by the floating zone method

We synthesized the 0.1, 0.5, 1.0, and 1.5% Ce-doped mullite single crystals by the floating zone method and evaluated their photoluminescence (PL) and thermally stimulated luminescence (TSL) properties. The single-phase orthorhombic structure was confirmed in all the samples from powder X-ray diffraction patterns. The transmittance spectra of all the samples showed the absorption related to the 4f-5d transitions of Ce3+ ions and optical band gap of mullite. The Ce-doped mullite single crystals had the PL attributed to the 5d-4f transitions of Ce3+ ions. In TSL properties, TSL glow curves had the glow peaks at 250 and 370 °C, and TSL spectra heated at 250 and 370 °C had the peak at around 390 nm owing to the Ce3+ ions. TSL dose response functions showed linear response from 0.01 mGy to 10 Gy for the 1.0% Ce-doped mullite single crystal and from 0.1 mGy to 10 Gy for the 0.1, 0.5, and 1.5% Ce-doped ones. The 1.0% Ce-doped mullite single crystal could be used multiple times for dosimetry. In addition, the TSL intensity of the 1.0% Ce-doped mullite single crystal after 7 days from X-ray irradiation was about 82.4% from immediately one after X-ray irradiation.

Synthesis of Tb-doped SiO2 glasses by spark plasma sintering method and evaluation of photoluminsecence and thermally stimulated luminescence properties

Tb-doped SiO2 glasses were synthesized by the spark plasma sintering (SPS) method, and optical and thermally stimulated luminescence (TSL) properties were investigated. The diffuse transmittance spectra of the 0.01, 0.05, and 0.1% Tb-doped SiO2 samples included the absorption due to the 4f-5d transitions of Tb3+ ions. In photoluminescence properties, all the Tb-doped SiO2 samples showed several emission peaks due to the 4f-4f transitions of Tb3+ ions and oxygen deficiency vacancy (ODC). The TSL glow curves indicated the glow peak at 140 °C, and only the emission peaks attributed to the 4f-4f transition of Tb3+ ions were observed in TSL spectra of the 0.01, 0.05, and 0.1% Tb-doped SiO2 samples. The integrated TSL intensity of the 0.1% Tb-doped samples had a proportional relationship in the range of 0.01–1000 mGy. The TSL intensity of the 0.05% Tb-doped glass after 72 h from X-ray irradiation was about 69% with respect to the one immediately after X-ray irradiation. In addition, the 0.05% Tb-doped SiO2 glass could use the multiple time for TSL dosimetry.

Thermally stimulated luminescence properties of magnesium orthosilicate single crystals doped with Dy3+ ions

In this study, we grew the Dy-doped Mg2SiO4 single crystals by the floating zone method to investigate the photoluminescence (PL) and thermally stimulated luminescence (TSL) properties. All the Dy-doped Mg2SiO4 showed the emission peaks at 480, 580, and 670 nm in PL and TSL spectra, and these peak wavelengths were typical for the 4f–4f transitions of Dy3+ ions. In the TSL glow curves, all the samples had the glow peaks at 50 °C, 200 °C, 280 °C, and 380 °C. The TSL dose response function of the 1% Dy-doped Mg2SiO4 single crystal showed a good linearity across 1–10000 mGy.

Thermal properties of paramagnetic radiation-induced defects in lithium orthosilicate containing breeder material

Lithium orthosilicate (Li4SiO4) containing ceramics are currently being developed as potential solid-state candidate materials for tritium breeding in future thermonuclear fusion reactors. Under the expected operational conditions, the tritium breeding material will be exposed to the simultaneous influence of several strong energetic factors, for example, radiation, temperature, magnetic field, etc. In the present work, thermal properties of the formed and accumulated paramagnetic radiation-induced defects (containing unpaired electrons) in the Li4SiO4 pebbles with a 2.5 wt.% surplus of silicon dioxide (SiO2) were investigated after irradiation with photons of different types and energies: X-rays with an energy up to 45 keV, gamma rays with an average energy of 1.25 MeV, and bremsstrahlung with an energy up to 6 MeV. The photon-irradiated pebbles were analysed using two complementary spectroscopic methods: electron paramagnetic resonance (EPR) and thermally stimulated luminescence (TSL). Individual signals contributing to the acquired EPR spectra, TSL glow curves and spectra were distinguished, deconvoluted and simulated in order to obtain a more detailed understanding about the local structure, electron configuration, and thermal stability of the accumulated radiation-induced defects. The simulation and deconvolution data were also compared with the results, which have been acquired for the long-term neutron-irradiated pebbles from the HICU experiment (High neutron fluence Irradiation of pebble staCks for fUsion).

Photoluminescence, scintillation, and dosimetric properties of Ce-codoped MgF2:Tb ceramics

Photoluminescence (PL), scintillation, and dosimetric properties of the Ce-codoped MgF2:Tb ceramics were evaluated. The Ce-codoped MgF2:Tb ceramics showed some PL emission peaks ascribed to the 4f–4f transitions of the Tb3+ ion and the 5d–4f transitions of the Ce3+ ion. It was confirmed that the emission wavelength of Ce3+ overlapped with the excitation wavelength of Tb3+, and the quantum yield was improved by codoping of Tb and Ce. In addition, the thermally-stimulated luminescence (TSL) glow curves mainly had the glow peak at 245 °C, and TSL spectra showed emission peaks due to the Tb3+ ion. TSL dose response functions were also evaluated, and the dynamic range with linear responses was from 0.01 to 1000 mGy.

Comparative study of structural, optical and magnetic properties of Er3+ doped yttrium gallium borates

The paper presents the results of a comprehensive study of yttrium gallium borate (YGa3(BO3)4) crystals low-doped (0.2 wt%) with erbium (Er3+) ions by in-situ X-ray diffraction (XRD), radioluminescence (RL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) techniques. Structural and elastic properties of YGa3(BO3)4: Er3+ crystals measured by the XRD method in the temperature range from 300 K to 1073 K have revealed the temperature variation of the volume thermal expansion coefficient. The analysis of RL spectra allowed us to assume the existence of the characteristic Er3+-related emission band located in the near-infrared region. The TSL spectra revealed strong peaks at low temperatures due to shallow traps and much less intense bands located above room temperature. Measurements of heat capacity in a wide temperature range allowed us to determine the Debye temperature θD ≈ 332 K. From the detailed analysis of the strongly anisotropic EPR spectra measured in YGa3(BO3)4:Er3+ crystals, the parameters of the spin Hamiltonian of Er3+ ions were determined: g⊥ = 9.34; g∥ = 1.269; A⊥ = 320.9 MHz; A∥ = 47.7 MHz. The temperature dependence of the spin-lattice relaxation rate of Er3+ ions was described well by the Orbach-Aminov process. It was proposed that Er3+ ions reside yttrium ions in YGa3(BO3)4 crystal lattice and are located in a slightly distorted prism made of six oxygen ions.

An insight into indium effect on the crystal structure and thermoluminescence of LiMgPO4: Combined experiment and ab initio calculations

In this work, indium doped LiMgPO4 is first considered as a dosimetric material. We present studies of the structural properties and thermally stimulated luminescence (TSL), as well as electronic structure of pure and indium doped LiMgPO4. We observed a nonmonotonic shift in the TSL peak with increasing indium concentration (x), which was associated with two different indium sites. We demonstrated that In3+ predominantly replaces Mg2+, but at indium concentration of less than 1%, it occupies the Li+ positions. The variation in indium substitution site affects also the depth of electron traps. Doping of LiMgPO4 with indium changes not only the TSL glow curves, but also the spectra of thermoluminescence. The spectrum of undoped LiMgPO4 consists of two broad bands located in the UV region (λ = 350 nm) and in the red region (λ = 640 nm), while there is only one line (λ = 630 nm) in the TSL spectra of LiMgPO4:In3+. The mechanism of thermoluminescence in pure and indium doped LiMgPO4 is discussed.

Effect of Tl doping on optical, TSL and OSL properties of Tl-doped RbBr transparent ceramics synthesized by SPS

The basic optical, thermally-stimulated luminescence (TSL) and optically-stimulated luminescence (OSL) properties of Tl-doped RbBr transparent ceramics synthesized by the spark plasma sintering were investigated. All the samples were transparent in the visible range. As the photoluminescence, TSL and OSL spectra, two emission bands around 380 and 520 nm were observed in all the prepared samples. The emissions around 380 and 520 nm would be attributed to the 3P1→1S0 transitions of Tl+ and off-center type of self-trapped exciton perturbed by the Tl+, respectively. As the OSL dose response functions, the sensitivity was confirmed to be as low as 1 mGy in the 0.5, 1.0 and 3.0% Tl-doped RbBr transparent ceramics. Using OSL of Tl-doped RbBr transparent ceramics, we have successfully obtained an X-ray imaging of the operational amplifier.

Thermally stimulated luminescence properties of Tm-doped MgAl2O4 transparent ceramics

Tm-doped MgAl2O4 transparent ceramics were synthesized by the Spark Plasma Sintering (SPS) method, and scintillation and thermally stimulated luminescence (TSL) properties were investigated. Under X-ray irradiation, the Tm-doped MgAl2O4 transparent ceramics clearly showed some emission peaks at 295, 360, 390, 455, 475, 500, 520, and 670 nm. Based on the observed scintillation decay curves, the origins of the emission peaks were attributed to 4f-4f transitions of Tm3+ ions. The emission peaks due to 4f-4f transitions of Tm3+ ions were also observed in a TSL spectrum. The TSL glow peaks of the Tm-doped MgAl2O4 transparent ceramics were detected at 68, 140, 200, 313, and 452 °C. The 1.0% Tm-doped MgAl2O4 transparent ceramics had a linear TSL response in a dose range from 0.01 to 100 mGy.

Thermally Stimulated Luminescence and Electron Spin Resonance Study of Gamma Irradiated Poly Carbonate

Polycarbonate (PC) is an industrially important polymer. Gamma irradiation effects of PC are investigated by thermally stimulated luminescence (TSL) and electron spin resonance (ESR) techniques. The TSL spectra of irradiated PC have shown two glow peaks, around 149oC (422 K) and 165oC (438 K). The observed glow peaks are analysed by initial rise methods, Chen’s method and modified initial rise method. The trap parameters corresponding to the two glow peaks and their activation energies are evaluated. A correlation of results between the three methods was observed. The glow peaks are assigned to be due to the release of trap centres facilitated by molecular motion of PC chains around the glass transition region. The trap centres are thought to be created due to the chain cleavages and subsequent reactions occurred due to irradiation of PC. The results are further confirmed by recording ESR spectra of irradiated PC under different conditions. Cite this ArticleB. Sanjeeva Rao, M. Papi Reddy, A. Raju et al. Thermally Stimulated Luminescence and Electron Spin Resonance Study of Gamma Irradiated Poly Carbonate. Emerging Trends in Chemical Engineering. 2017; 4(2): 23–39p.

Size effects and radiation resistance of BaF2 nanophosphors

Abstract The stationary X-ray excited luminescence (XEL) spectra at 80 and 294 K as well as the thermally stimulated luminescence (TSL) in the 80–300 К range of a single crystal and nanoparticles of BaF2 with various grain sizes of 20–113 nm were studied. Under the influence of size effects in BaF2 nanophosphors, a short-wave displacement of self-trapped excitons emission band was observed compared to the corresponding single crystal, and its splitting into two components peaked at 324 and 305 nm for 294 K, and at 321 and 305 nm – for 80 K. A slight decrease of radiation resistance of BaF2 nanophosphors was observed in comparison to single crystal, which led to additional band of X-ray excited luminescence at ∼410 nm that may be associated with emission of exciton localized in the vicinity of anionic vacancies of the matrix. At the same time, it was established that radiation resistance of BaF2 nanophosphors is much higher compared to the corresponding CaF2 nanophosphors. With the use of integral TSL curves and TSL spectra, it has been shown that VH-centers with delocalization temperature of ∼140 K are the main hole centers that occur in BaF2 nanoparticles under X-ray irradiation influence, while in ВаF2 single crystals – these are Vk - and H-centers with delocalization temperatures at 113 and 198 К, respectively. Significant long-wave displacement of emission bands associated with (VH-F)- and (H-F)- recombinations, compared to the spectra of corresponding single crystal, was observed in BaF2 nanophosphors.

Radiation induced luminescence properties of Eu-doped SiO2 glass synthesized by spark plasma sintering

We successfully synthesized Eu-doped SiO2 glasses by the spark plasma sintering method, and the prepared glasses doped with various concentrations of Eu (0, 0.002, 0.020 and 0.200%) were studied for optical, dosimeter and scintillation characteristics. The undoped sample showed the luminescence possibly due to the oxygen vacancy in photoluminescence (PL) and scintillation. The Eu-doped samples indicated PL due to the 5d-4f transitions of Eu2+ characterized as a broad emission peaking at approximately 450 nm. In the scintillation, we observed the emission of Eu2+ and Eu3+. The PL and scintillation decay time constants ascribed to the emission from Eu2+ were 1.96–1.99 μs and 1.63–1.70 μs, respectively. In the synthesized samples, the 0.002% Eu-doped sample indicated the highest PL quantum yield of 68.6%. Moreover, the highest light yields among the present samples were 407 photons/MeV under 241Am α-ray exposure. The prepared samples showed relatively low afterglow level. The materials also exhibit thermally stimulated luminescence (TSL) properties with a major glow peak around 200 °C, and when the TSL spectra were observed after the irradiation of X-rays (10 Gy), we confirmed that the luminescence was ascribed to the transitions of Eu3+ in addition to Eu2+. Overall, the samples showed a high sensitive response of TSL which showed a linearity from 0.01 mGy to 100 mGy.