Thermally Stimulated Luminescence Glow Peak Research Articles

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.

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.

Scintillation and thermoluminescent properties of Dy-doped calcium borate chloride

Calcium borate chlorides (Ca 2 BO 3 Cl) with different concentrations of Dy 3+ were fabricated by the conventional solid-state reaction with an aim to develop themoluminescent materials for radiation dosimetry, and their scintillation and thermally-stimulated luminescence (TSL) properties were evaluated systematically. Several scintillation peaks at approximately 485, 580 and 675 nm due to the 4f-4f transitions of Dy 3+ appeared in the Dy 3+ -doped Ca 2 BO 3 Cl, and the 1.0% Dy 3+ -doped Ca 2 BO 3 Cl showed the highest scintillation intensity. In the temporal scintillation profiles, the decay time constants of the Dy 3+ -doped Ca 2 BO 3 Cl were about 0.6 ms, which was a typical value for the 4f-4f transitions of Dy 3+ . Furthermore, the Dy 3+ -doped Ca 2 BO 3 Cl showed efficient TSL with glow peaks at 110 and 250 °C originating from the 4f-4f transitions of Dy 3+ . Among the sample investigated, the 1.0% Dy 3+ -doped Ca 2 BO 3 Cl exhibited the highest TSL intensity, and the linear dose response of the TSL glow peak at 250 °C was confirmed to be in the dose range from 0.1 to 100 mGy for the 1.0% Dy 3+ -doped Ca 2 BO 3 Cl. • Dy-doped calcium borate chlorides were fabricated by the conventional solid-state reaction for radiation dosimetry. • The chlorides showed efficient TSL due to the 4f-4f transitions of Dy 3+ with a glow peak at 250 °C. • Linear TSL dose response was confirmed to be in the dose range from 0.1 to 100 mGy.

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.

Dosimetric properties of undoped and Tb-doped MgAl2O4 transparent ceramics

Undoped and Tb-doped MgAl2O4 transparent ceramics were synthesized by the Spark Plasma Sintering (SPS) method, and dosimetric properties were investigated. The Tb-doped sample showed thermally stimulated luminescence (TSL) and optically stimulated luminescence (OSL), in which the emission center was Tb3+ ions. The TSL glow peaks of the Tb-doped sample are detected at 64, 151, 235, 299, and 385 °C. The Tb-doped sample had a linear TSL response in a dose range from 0.01 to 1000 mGy.

Optical, scintillation, and dosimetric properties of dy-doped MgAl2O4 transparent ceramics

Dy-doped MgAl2O4 transparent ceramics were synthesized by the Spark Plasma Sintering (SPS) method, and photoluminescence (PL), scintillation, and dosimetric properties were investigated. Under excitations of 300, 360, and 390 nm, the Dy-doped sample clearly showed some emission peaks at 480, 580, and 660 nm. Based on the observed PL decay curves, the origins of the emission peaks were attributed to 4f-4f transitions of Dy3+ ions. The emission peaks due to 4f-4f transitions of Dy3+ ions were also observed in scintillation. As dosimetric properties, the Dy-doped sample showed thermally stimulated luminescence (TSL). The TSL glow peaks of the Dy-doped samples were detected at 53, 141, 193, 245, 304, 381, and 469 °C. The 0.1 % Dy-doped sample had a linear TSL response in a dose range from 0.1–100 mGy.

Trap level spectroscopic investigations of U: ZnAl2O4: Role of defect centres in the TSL process

In order to evaluate the trap level spectroscopic properties of Uranium in ZnAl2O4 spinel host, undoped and Uranium doped ZnAl2O4 samples were synthesized. From photoluminescence (PL) data it was confirmed that uranium gets stabilized in the system as UO66− (octahedral uranate). Electron spin resonance (ESR) studies for the gamma irradiated sample suggested the formation of O2−, F+ and V centres. From the TSL (thermally stimulated luminescence) data, the trap parameters such as frequency factor and activation energy etc. were evaluated. From ESR-TSL correlation it was confirmed that the destruction of O2− ion coincides with TSL glow peak appeared at 332 K.

Photoluminescence, scintillation and TSL properties of Ce-doped Sr(PO3)2 glasses

In this study, we have synthesized Sr(PO3)2 glasses non-doped and doped with Ce (0.01, 0.05, 0.1, 1.0 and 3.0 mol%) prepared by the conventional melt-quenching method and investigated the optical properties [transmittance spectra, photoluminescence (PL) spectra, PL excitation spectra and PL decay times], scintillation properties with X-rays (scintillation spectra, scintillation decay times) and thermally-stimulated luminescence (TSL) properties (glow curves and dose response functions). The PL spectrum of the Ce-doped samples consist of an intense emission band due to the 5d–4f transitions of Ce3+ ion peaking at 350 nm. The decay time of the corresponding emission was 32–37 ns depending on the Ce concentration. The samples also showed scintillation with X-ray having a spectrum of an intense emission band peaking at 350 nm due to the Ce3+ ions, and decay time was 34–217 ns. The TSL glow peaks were observed at 190 and 450 °C for the Ce-doped glasses, and the dynamic range was confirmed at least over a three orders of magnitude 100–103 mGy.

Development of BaF2 transparent ceramics and evaluation of the scintillation properties

We have developed BaF2 transparent ceramics by using a spark plasma sintering (SPS), and investigated optical, scintillation and dosimeter properties, in comparison with a BaF2 single crystal. The photoluminescence emission peak of transparent ceramics prepared in a vacuum condition appeared around 500 nm. Under X-ray irradiation, emissions at 190 and 220 nm due to auger-free luminescence (AFL) were observed in the ceramic samples. The scintillation light yield of the BaF2 transparent ceramics was evaluated to be about 6000 photons/MeV under 137Cs γ-rays. In addition, the afterglow level of ceramic sample was lower than that of the single crystal. Thermally-stimulated luminescence glow peaks were observed at 50, 105, 140, 205, 280 and 420 °C in all the samples.

Scintillation, TSL and OSL properties of Ce-doped 30Zn3(PO4)2-70Al(PO3)3 glasses

In this study, we have synthesized 30Zn3(PO4)2-70Al(PO3)3 glass samples doped with different concentrations of Ce (0, 0.1, 0.3, 1.0, and 3.0 mol%) by the conventional melt quenching method, and we have evaluated the optical, scintillation and dosimeter properties such as thermally-stimulated luminescence (TSL) and optically-stimulated luminescence (OSL). The photoluminescence (PL) spectrum showed an intense emission band due to the 5d–4f transitions of Ce3+ ion peaking at 330 nm as well as a weak emission due to the host at 440 nm. The decay times of corresponding emissions were 20–24 ns and 7 ns, respectively. The scintillation emissions also showed intense emissions at 330 and 440 nm due to the Ce3+ ion and host, and the decay times were 7–13 ns and 31–35 ns, respectively. The TSL glow peaks were observed mainly around 150–190 °C for Ce-doped samples while the non-doped sample showed a glow peak around 300–400 °C. The TSL intensity increases with increasing the X-ray dose delivered, and the dose response curve showed a good linearity over the dose range of 0.01–10 Gy. The OSL was observed around 330 nm during the stimulation at 410 nm.

Optical and scintillation properties of Pr-doped 12CaO·7Al2O3 single crystals grown by the FZ method

We have investigated the photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) dosimeter properties of Pr-doped 12CaO·7Al2O3 (Pr:C12A7) crystals prepared by the floating zone (FZ) method. In PL emission and excitation spectral measurements, some emission bands around 600–650 and 850–950 due to the 4f-4f transitions of Pr3+ were observed under excitation at 450–500nm. The decay time constants of these emissions were approximately 78μs. The scintillation spectra showed the 4f-4f transition related emissions of Pr3+ at similar wavelengths with those in PL. The scintillation decay time constants of Pr-doped samples except 0.1% Pr-doped one were around 50μs, and the latter value was shorter than those of PL. In contrast, the 0.1% Pr-doped sample showed the scintillation decay time constant about 80μs. The PL quantum yield of 0.5% Pr:C12A7 crystal was the highest among the present samples. After X-ray irradiations, the 0.5, 1.0 and 2.0% Pr-doped samples showed intense and broad TSL glow peak around 95°C while the undoped and 0.1% Pr-doped samples showed no significant signal.

Influence of SrF2-doping in AlN ceramics on scintillation and dosimeter properties

In this study, we synthesized undoped AlN and SrF2-doped AlN (AlN-SrF2) ceramics by Spark Plasma Sintering (SPS), and we characterized their optical, scintillation and dosimeter properties. The prepared undoped AlN ceramic had gray color and visually non-transparent whereas, with an addition of SrF2, the transparency improved and became translucent. The measured in-line transmittance was approximately 0.2% at wavelengths longer than 500 nm. While the addition of SrF2 decreased the scintillation intensity, the decay time was significantly fastened, which is a great advantage for fast photon counting-based measurements. Both the thermally-stimulated luminescence (TSL) and optically-stimulated luminescence (OSL) showed good linear response from the milli-gray range to over 10 Gy. The sensitivity seems to decrease by an addition of SrF2 as it suppresses structural defect centers which are responsible for dosimeter properties. However, the main TSL glow peak position shifts to higher temperature with the addition of SrF2, which indicates that inclusion of SrF2 improves the TSL signal stability.

Optical and scintillation properties of Nd-doped SrAl2O4 crystals

Nd-doped SrAl2O4 (Nd:SrAl2O4) crystals were prepared by a floating zone (FZ) method with different dopant concentrations. The photoluminescence (PL) measurements under visible light excitations confirmed strong near infrared (NIR) emissions around 890 nm, which is due to the 4f-4f transitions of Nd3+, and the decay time constants were 300–400 μs. Furthermore, VUV excitations revealed two broad emissions around 250–450 and 500–700 nm, which were attributed to self-trapped excitons (STEs) perturbed by Nd3+. Moreover, the X-ray induced scintillation spectra showed some small peaks at around 380 nm in addition to NIR emissions at 1064 nm similarly seen in PL. The former scintillation decay time constants were 30–40 μs. In the undoped sample, these emissions mentioned above were not present but a weak broad emission around 450 nm appeared. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks were observed in the Nd-doped samples at around 100 and 250 °C.

Evaluation of Ce:SrAl2O4 crystalline scintillators

In this study, Ce-doped SrAl2O4 (Ce:SrAl2O4) crystals were prepared by a floating zone (FZ) method and experimental evaluations were performed for scintillator applications. In photoluminescence (PL) with an excitation around 320nm, an intense broad emission peak appears around 380nm due to the 5d-4f transitions. The PL decay time constants are approximately 30ns. The X-ray induced scintillation spectrum also shows an intense broad emission peak around 380nm. Among the samples evaluated with different concentrations of Ce, the absolute light yield under 137Cs is considerably high (∼3900ph/MeV) when the concentration of Ce is 1.0%. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks are observed at 110, 210 and 330°C. The samples also shows optically stimulated luminescence (OSL) after X-ray irradiation, in which the emission appears around 380nm due to the 5d-4f emission bands of Ce3+ while the samples is exposed to the stimulation light at 655nm.

Storage luminescence and scintillation properties of Eu-doped SrAl2O4 crystals

Eu-doped SrAl2O4 (Eu:SrAl2O4) crystals are prepared by a floating zone (FZ) method. In photoluminescence (PL), an intense broad emission peak around 510nm due to 5d-4f transition of Eu2+ appear under excitation at 250–450nm. The PL decay time constants are about 800ns due to the 5d-4f transitions of Eu2+. In the nondoped sample, emission peaks around 480 and 560nm are observed upon excitation at 316nm. The X-ray induced scintillation spectra also show an intense broad emission peak around 510nm, and the decay time constants are approximately 500ns. In the pulse height spectra of the 2.5% Eu:SrAl2O4 crystal, the absolute light yield is ~46,000ph/MeV. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks are observed at 120 and 400°C. In optically stimulated luminescence (OSL) after X-ray irradiation, emission peaks are observed around 510nm while exposing the samples to the stimulation light at 800nm.

Radiation induced centers in irradiated SrB4O7 doped europium and their role in thermally stimulated reactions: Thermally stimulated luminescence, fluorescence and electron paramagnetic resonance studies

Polycrystalline samples of strontium tetraborate (SrB4O7: SBO) samples doped with different concentrations of europium (0%, 0.05%, 1% and 2%) were synthesized using solid state reaction in air at high temperature. These samples were characterized by X-ray diffraction (XRD), photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) techniques. X-ray diffraction studies indicated that SrB4O7 has orthorhombic structure with lattice parameters a=4.237±0.001, b=4.431±0.001, c=10.704±0.010, space group Pnm2i, Z=2. Thermally Stimulated Luminescence (TSL) investigations on the gamma irradiated sample showed an intense glow peak at 407K and a weak glow peak at 500K. The trap parameters namely activation energy (E), order of kinetics (b) and the frequency factor (s) for the main peak at 407K were determined using the glow curve method. Fluorescence studies showed weak emission at ca 367nm, which was attributed to f-d transition (4f65d-4f7) of Eu2+ ions in the host lattice, whereas an intense emission in the range 570–650nm was assigned to 5D0→7FJ, J=0,1,2,3 and 4 transition of Eu3+ in the host lattice. The large value of I(R)/I(O) suggested that Eu3+ ions are situated at sites without center of inversion (lower symmetry) in SBO matrix. EPR studies suggested the formation of boron–oxygen hole trapped center viz, BOHC, electron trapped at oxygen vacancies and some impurity radicals like NO32− and CO2− radicals in SBO on irradiation. EPR temperature variation studies in the range 300–475K on gamma irradiated europium doped samples, suggested a recombination process occurring between boronoxygen hole trapped species and electron trapped species and subsequently energy is transferred to Eu3+ ion, which on de-excitation yields thermally stimulated luminescence yielding an intense TSL glow peak at 407K.