Thermally Stimulated Luminescence Glow Research Articles

Thermally Stimulated Luminescence in ZnSe:Ag and ZnSe:(Ag, Gd) Phosphors

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

X-ray-induced luminescence properties of Na3AlF6 doped with TmF3

Tm-doped Na3AlF6 ceramics were prepared by the spark plasma sintering (SPS) method with different Tm concentrations (0.01, 0.1, 1, 3, 5 %), and optically-stimulated luminescence (OSL) and thermally-stimulated luminescence (TSL) were investigated. In the OSL properties, emission peaks were observed at 300 and 350 nm under 500 nm stimulation due to 4f-4f transitions of Tm3+. The 0.1, 1, and 3 % Tm-doped samples indicated a dose response linearity between 100 mGy and 10 Gy. The TSL glow peaks of Tm-doped samples were detected at 80, 120, 300, and 410 °C. The 0.1, 1, and 3 % Tm-doped samples indicated a dose response linearity over the range of 0.01–1000 mGy at dose response functions.

Photoluminescence, scintillation, and TSL properties of Dy-doped BaCaBO3F

We fabricated BaCaBO3F (BCBF) with various Dy concentrations (0.1 %, 1 %, and 5 %), and evaluated the luminescence properties for radiation dosimetry. Sharp scintillation peaks originating from the 4f → 4f transition of Dy3+ were observed. Furthermore, thermally stimulated luminescence (TSL) glow curves were recorded, and a TSL glow peak at approximately 120 °C was observed. The 0.1 % Dy-doped BCBF exhibited the highest TSL intensity, and dose response curves of the 0.1–1 % Dy-doped BCBF were obtained in the 0.1–10000 mGy range. Moreover, at least seven activation energy levels related to TSL were confirmed by the TSL isothermal decay analysis.

Comparative study of optical and dosimetric properties of Mn-doped CaF2

Mn-doped CaF2 has been used as a thermoluminescence detector. On the other hand, dosimetric properties of Mn-doped CaF2 transparent ceramics have not been thoroughly investigated. In this study, transparent ceramics (TC) of Mn-doped CaF2 were fabricated, and the optical and thermally stimulated luminescence (TSL) properties were investigated in comparison with Mn-doped CaF2 single crystal (SC) and opaque ceramics (Cer). The transmittance at 500 nm of the TC, SC, and Cer specimens was 58, 91, and 0%, respectively. All the specimens showed a PL peak at 490 nm with 340, 400, and 450 nm excitations, originating from d-d transitions of Mn2+ ions. The emission and excitation spectra changed with X-ray irradiation, and this phenomenon was attributed to optically stimulated luminescence. All the specimens mainly had a TSL glow peak at 300 °C. The TC specimen exhibited a higher TSL intensity than the SC and Cer specimens.

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.

Paramagnetic radiation-induced radicals in calcium pyrophosphate polymorphs

Calcium pyrophosphate (Ca2P2O7) is a promising material for biomedical and optical applications; however, relatively little is documented on the radiation-induced point defects of the material. This study reports on the formation, identity, and properties of X-ray-induced radicals in γ-, β-, and α-polymorphs of Ca2P2O7. Complementary thermally stimulated luminescence (TSL), electron paramagnetic resonance (EPR), and solid-state nuclear magnetic resonance (NMR) spectroscopy techniques were combined to reveal the effects of ionising radiation on each polymorph. The high temperature polymorphs β-, and α-Ca2P2O7 exhibited diminishing variety and intensity of EPR signals, whereas the opposite trend was observed in the TSL response. TSL glow curves consisted of multiple peaks in the temperature range of 20–350 °C, with maximum emission intensity located at approximately 600 nm. Multiple electronic spin 1/2 paramagnetic centres were identified on the basis of spin-Hamiltonian parameters determined from EPR spectra simulations. Annealing kinetics of the individual paramagnetic centres were determined to provide an interpretation of the complex nature of TSL glow curves. A decrease of the 31P spin-lattice relaxation T1 times after irradiation was detected for all Ca2P2O7 polymorphs. The results highlight the importance of structure, morphology, and synthesis conditions on the formation of charge traps in Ca2P2O7 and expand the knowledge base on the variety of radiation-induced radicals in phosphate materials.

UV irradiated thermally stimulated luminescence investigation of SrWO4: Pr3+ phosphor

The article explores the thermally stimulated luminescence (TSL) properties of SrWO4: Pr3+ phosphor. The material exhibits excellent glow response due to the presence of traps after excitation at 254 nm UV light. The effect of change of linear heating rate and irradiation doses on TSL glow curve parameters is explained properly. The reusability of the material is ensured by repeating the same measurement several times. Trap parameters are calculated using computerized glow curve deconvolution (CGCD) mthod by considering the general order kinetics of the peaks.

Fast response 4f15d1→4f2 emission and host-to-impurity energy transfer in Pr3+ doped Na3LuSi3O9 double salt silicate

Understanding of host-to-impurity energy transfer process is crucial for the development of efficient and fast response scintillator materials. In this work, Pr3+ doped Na3LuSi3O9 (NLS) double salt silicate has been successfully synthesized using a high temperature solid-state reaction method and further comprehensively characterized by means of XRD measurements, crystal structure refinement, luminescence spectroscopic and time-domain study upon VUV-UV and X-ray synchrotron excitation, and thermally stimulated luminescence (TSL) study. Based on these results a model of host to Pr3+ 4f15d1 and 4f2 has been proposed. It has been demonstrated that NLS:Pr3+ has a good potential for fast response scintillator applications due to the presence of an efficient energy transfer from host electronic excitations to Pr3+ 4f15d1 states. The Pr3+ 4f15d1→4f2 emission reveals a good thermal stability and is characterized by a lifetime of about 16 ns. Upon pulse X-ray excitation the main fast decay component is accompanied by slower one with lifetime of about 64 ns that is ascribed to the presence of shallow traps which retrap carriers and cause appearance of delayed recombination. Parameters for the corresponding traps have been calculated based on the TSL glow curve analysis.

Charge Transfer and Charge Trapping Processes in Ca- or Al-Co-doped Lu2SiO5 and Lu2Si2O7 Scintillators Activated by Pr3+ or Ce3+ Ions.

Lutetium oxyorthosilicate Lu2SiO5 (LSO) and pyrosilicate Lu2Si2O7 (LPS) activated by Ce3+ or Pr3+ are known to be effective and fast scintillation materials for the detection of X-rays and γ-rays. Their performances can be further improved by co-doping with aliovalent ions. Herein, we investigate the Ce3+(Pr3+) → Ce4+(Pr4+) conversion and the formation of lattice defects stimulated by co-doping with Ca2+ and Al3+ in LSO and LPS powders prepared by the solid-state reaction process. The materials were studied by electron paramagnetic resonance (EPR), radioluminescence spectroscopy, and thermally stimulated luminescence (TSL), and scintillation decays were measured. EPR measurements of both LSO:Ce and LPS:Ce showed effective Ce3+ → Ce4+ conversions stimulated by Ca2+ co-doping, while the effect of Al3+ co-doping was less effective. In Pr-doped LSO and LPS, a similar Pr3+ → Pr4+ conversion was not detected by EPR, suggesting that the charge compensation of Al3+ and Ca2+ ions is realized via other impurities and/or lattice defects. X-ray irradiation of LPS creates hole centers attributed to a hole trapped in an oxygen ion in the neighborhood of Al3+ and Ca2+. These hole centers contribute to an intense TSL glow peak at 450-470 K. In contrast to LPS, only weak TSL peaks are detected in LSO and no hole centers are visible via EPR. The scintillation decay curves of both LSO and LPS show a bi-exponential decay with fast and slow component decay times of 10-13 ns and 30-36 ns, respectively. The decay time of the fast component shows a small (6-8%) decrease due to co-doping.

Photoluminescence and dosimetric properties of Tb-doped Na3AlF6 ceramics

Tb-doped Na3AlF6 ceramics with different concentrations were synthesized by the spark plasma sintering (SPS) method, and photoluminescence (PL), optically-stimulated luminescence (OSL), and thermally-stimulated luminescence (TSL) properties were investigated. In the PL property, Tb-doped Na3AlF6 ceramics showed emission peaks at 420, 440, 460, 480, 550, 580, and 620 nm and the decay time constants due to 4f–4f transitions of Tb3+. Under the stimulation at 750 nm, Tb-doped Na3AlF6 ceramics showed OSL peaks due to 4f–4f transitions of Tb3+. The TSL glow peaks were detected at 120, 200, and 280 °C in Tb-doped Na3AlF6 ceramics. The 0.1 and 1% Tb-doped Na3AlF6 ceramics had linear dose response over the dose range of 0.01–1000 mGy.

Scintillation and dosimeter properties of Pr2O3-doped Ga2O3–K2O–La2O3 glasses

Rare-earth-activated glasses have attracted research attention for radiation measurements for decades because of several practical merits, including their amenability towards mass production, large-volume fabrication, easing shaping, and their low cost. Various glass materials (e.g., borate and silicate glasses) have been characterized. In this study, photoluminescence, scintillation, and thermally stimulated luminescence (TSL) characteristics were observed for Pr3+-activated gallate glasses (69Ga2O3–20K2O–(11-x)La2O3–xPr2O3). Clear photoluminescence and scintillation peaks derived from the 4f-4f transitions of Pr3+ appeared in the range of 480–670 nm, where the photoluminescence and scintillation decay time constants attributable to the 4f-4f transitions of Pr3+ were on the order of microseconds. The thermoluminescence of these glasses was also investigated, where a broad TSL glow peak was detected at approximately 90°C. The lowest measurable dose limit is approximately 1 mGy. Moreover, isothermal decay curve analysis suggested that nine trap levels are associated with the TSL.

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.

Dosimetric properties of Mn2+-doped Ca2BO3Cl

We synthesized Ca2BO3Cl with various amounts of MnCl2 to fabricate phosphors for radiation dosimetry. After the synthesis, we evaluated their scintillation, thermally-stimulated luminescence (TSL), and optically-stimulated luminescence (OSL) characteristics. A scintillation peak derived from the 4T1 → 6A1 transition of Mn2+ appeared at approximately 600 nm in the MnCl2-doped Ca2BO3Cl. Further, their decay time constants were approximately 0.13 ms that should be ascribed to the 4T1 → 6A1 transition. Moreover, the MnCl2-doped Ca2BO3Cl exhibited TSL glow peaks at approximately 85 °C, 170 °C, and 280 °C. The linear response of the 0.1% MnCl2-doped Ca2BO3Cl was confirmed in the X-ray dose range of 10–3000 mGy. In addition, a weak OSL peak derived from the 4T1 → 6A1 transition was detected at around 600 nm from the 0.1% and 0.5% MnCl2-doped Ca2BO3Cl.

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.

Effect of Tm doping on photoluminescence, scintillation, and thermally stimulated luminescence properties of MgAl2O4 single crystals

The Tm-doped MgAl2O4 single crystals were synthesized by using Xe arc lamps-equipped floating zone furnace. The synthesized crystals exhibited luminescence due to the 4f-4f transitions of Tm3+ in photoluminescence (PL), scintillation, and thermally stimulated luminescence (TSL). In all of PL, scintillation, and TSL, the 0.5% Tm-doped crystal showed the highest luminescence intensity. In TSL dose response functions, the 0.5% Tm-doped crystal showed sensitivity from X-ray irradiation with 0.1 mGy. In addition, we measured linear energy transfer (LET) dependence on TSL glow curve of the crystal and X-ray imaging test taken by TSL. We revealed the spatial resolution of the crystal was 100 μm.

Dy-concentration dependence on dosimetric properties of CaF2 transparent ceramics

In this study, we synthesized Dy-doped CaF2 transparent ceramics with several concentrations and evaluated optical, thermally stimulated luminescence (TSL), and optically stimulated luminescence (OSL) properties. The 0.05, 0.1, and 0.5% Dy-doped samples had diffuse transmittance of approximately 60% at 500 nm, and the absorption band appeared at around 280 nm after X-ray irradiation. The photoluminescence (PL) excitation wavelengths were 255, 295, 325, 350, 360, and 390 nm. When Dy concentration was 0.1%, the PL quantum yield was maximum. The OSL peaks of the Dy-doped samples was observed at 480, 570, and 660 nm by the optical stimulation at 280 nm. The TSL glow curves of the 0.5 and 1.0% Dy-doped samples consisted of the glow peaks at 75, 160, and 200 °C. The minimum detectable dose of the 0.5% Dy-doped sample as the OSL and TSL dosimeters was 15 mGy and 0.28 μGy, respectively.

Optical and thermally-stimulated luminescence properties of Ce-doped Al2O3 transparent ceramics

Optical and thermally-stimulated luminescence (TSL) properties of Ce-doped Al2O3 transparent ceramics were investigated. The transparent ceramics were synthesized by the spark plasma sintering method. The Ce-doped Al2O3 transparent ceramics showed photoluminescence (PL), radioluminescence, and TSL peaking at around 400 nm, caused by 5d-4 f transitions of Ce3+. The PL decay curve consisted of two components with decay time constants of 21 and 43 ns. The TSL glow curves had glow peaks at 71, 130, 184, 251, 284, and 362 °C. The 0.1% Ce-doped Al2O3 transparent ceramic exhibited the maximum TSL intensity among the present samples. The minimum detectable dose was turned out to be 0.03 mGy.

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.

TSL and OSL properties of undoped and Eu-doped NaMgF3 translucent ceramics prepared by a spark plasma sintering method

Translucent ceramics of undoped and Eu-doped NaMgF3 were synthesized by the spark plasma sintering method. Their optical, scintillation, thermally stimulated luminescence (TSL), and optically stimulated luminescence (OSL) properties were examined. In photoluminescence and scintillation spectra, Eu-doped NaMgF3 mainly showed the emission peaks at 360 and 375 nm, ascribed to 4f-4f and 5d-4f transitions of Eu2+, respectively. The TSL glow curve consists of the glow peaks at 94, 132, 166, 203, 249, 316, and 377 °C. The OSL signal could be detected by stimulation at 415 nm. The dominant luminescence center in TSL and OSL processes was Eu2+ ions, showing the emission peaks at 360 and 375 nm. The Eu-doped NaMgF3 had linear TSL and OSL responses from an irradiation dose of 0.01 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).