Search

The temperature behavior of Tl4HgI6 photoluminescence spectra is presented. The emission spectra are studied in the temperature range between 4.5 and 300 K and in the spectral range 350–650 nm. Two main emission bands at ∼551 nm and ∼448 nm are observed corresponding to the emissions of HgI2 and Tll impurity centers. It is assumed that the low-temperature emission band at ∼520 nm corresponds to the recombination of the exciton. The luminescence peaks observed in emission spectra in the range between 350 and 410 nm correspond to the phonon repetitions. The excitation spectra of emission bands are measured at 4.5 K and compared with the electron density of states.

Characteristics of the intrinsic and Bi3+-related luminescence of YNbO4:Bi powders with different Bi contents are studied at 4.2–500 K by steady-state and time-resolved spectroscopy methods. The emission of YNbO4:Bi is suggested to be of an exciton origin. The main Bi3+-related emission band (2.53 eV) excited at 4.09 eV is ascribed to the radiative decay of an exciton localized around a single Bi3+ ion. A weak lower-energy (2.41 eV) emission is ascribed to an exciton localized around a dimer Bi3+ center. No emission arising from the 3P1,0 → 1S0 transitions of a Bi3+ ion is found. The structure and parameters of the exciton states, responsible for the luminescence of YNbO4:Bi, as well as the radiative and nonradiative processes ongoing in these states are clarified. From the dependence of the afterglow intensity on the irradiation energy, the band gap energy of YNbO4 is estimated to be 5.3–5.4 eV.

The results of X-ray diffraction studies of the Gd(Mg0.95−x,ZnxMn−0.05)B5O10 down-converting phosphor as a function of Mg–Zn composition are presented. The lattice parameters and unit cell volumes of GdMg0.95−xZnxMn0.05B5O10 pentaborates are examined. The relationships between the structure and optical properties of these materials are explicated based on the results of theoretical calculations of the energy structure. The effect of pressure on the luminescence of Mn2+ in this system was studied up to ca. 32 GPa. The observed quenching of Mn2+ luminescence is due to the crossing of the emitting 4T1g level with the non-emitting 2T2g state. This crossing sets a long-wavelength limit on the possibility of observing the emission of Mn2+ ions, which is around 850 nm.

Silver (Ag) plasmonic structures on the surface of Сe and Yb co-doped yttrium aluminium garnet fluorescent epitaxial films were prepared by the magnetron sputtering technique. The nucleation and growth of Ag nanoparticles (NPs) were controlled by a thermal annealing process. Annealing of the samples at T ≥ 350 °C results in growth of Ag NPs size. A broad absorption band peaking in the range from 440 to 550 nm was observed due to the dipole mode of the surface plasmon resonance (SPR) of Ag NPs. Photoluminescence emission and excitation spectra were measured for samples having different concentrations, sizes and shapes of Ag particles. Plasmon-enhanced Ce 3+ luminescence was observed for samples with particles bigger than 50 nm. On the other hand luminescence quenching was observed for samples with high Ag concentration and smaller NPs size. Presented luminescence results suggest that there are two competitive effects, namely enhancement and quenching, affecting the luminescence in the presence of Ag NPs. The enhancement of Ce 3+ luminescence is mainly attributed to local field effect i.e. the SPR of Ag NPs causes an intensified electromagnetic field around them, resulting in enhanced optical transitions of Ce 3+ ions in the vicinity of Ag NPs. The quenching effect, in the presence of Ag NPs, suggests an energy transfer from Ce 3+ ions directly to them. The competition between the plasmonic enhancement and the quenching effect is discussed for samples with different nanoparticles concentrations and sizes.

The paper contains detailed crystal structure and photoluminescence studies of the Bi3+ and Bi3+-Eu3+ co-doped Gd3Ga5O12 (GGG) garnet. The studied materials have been synthesized in the form of microcrystalline powders by the common solid-state reaction method. Precise crystal structure parameters were derived from the X-ray powder diffraction data. Photoluminescence studies were done by the steady-state and time-resolved techniques in the 4.2–400 K temperature range. The studied materials show no UV luminescence caused by electronic transitions of a Bi3+ ion. The observed luminescence in visible is interpreted by excitons localized around Bi3+ ions. In particular, two emission bands located at 2.55 eV (486 nm) and 2.05 eV (605 nm) at 4.2 K were revealed. The main emission band at 2.55 eV is attributed to the triplet relaxed state of excitons localized around single (regular) Bi3+ ions, whereas the weaker band at 2.05 eV is related to some associates of a single Bi3+ ion with a crystal lattice defect. The performed studies for Bi3+-Eu3+ co-doped samples indicate that the energy transfer from Bi3+ to Eu3+ is radiative and is caused by reabsorption of the Bi-related exciton emission by Eu3+ ions. The studied materials were also characterized as a single-phase converting phosphor for near-UV excited white LEDs. The possibility of the emission color tuning from blue to orange-red at UV excitation by the way of changing of Bi3+ and Eu3+ concentrations was shown.

Steady-state and time-resolved emission and excitation spectra and the luminescence decay kinetics are studied in the 4.2–500 K temperature range for the blue intrinsic emission and the yellow Bi3+ - related emission of YVO4:Bi, LuVO4:Bi, and GdVO4:Bi microcrystalline powders. It is suggested that the Bi3+ - related absorption (excitation) band, peaking around 3.75 eV, arises from the electronic transition from the ground 1S0 state of a Bi3+ ion to its excited 3P1 state located inside the conduction band (CB). The excitation in the Bi3+ - related absorption band is suggested to result in an electron release from the 3P1 level of Bi3+ into the CB and its subsequent recombination with the hole remained at the Bi3+ ion. As a result, an exciton localized around the single Bi3+ ion is created. The radiative decay of this exciton is accompanied with the Bi3+ - related 2.12–2.19 eV emission. The origin, structure, and parameters of the exciton states, responsible for the luminescence of the Bi3+ - doped vanadates, and the processes taking place in these states are investigated and discussed. No ultraviolet emission arising from the 3P1,0 - 1S0 transition of Bi3+ ions is found. From the afterglow excitation spectra, the band gap energy in the investigated vanadates is estimated to be about 4.20–4.25 eV.

Yttrium alumino bismuth borosilicate (YABiBS) glasses doped with RE3+ ions (Eu3+, Dy3+, Dy3+- Eu3+) have been synthesized via standard melt quenching technique and their emission properties were investigated. Optical analysis of these glasses is characterized by absorption and luminescence. XRD spectra reveal that these glasses have amorphous nature. The absorption spectra of these co-doped glasses consist five bands of Dy3+ which are assigned to 6H15/2 → 6F3/2 (750 nm), 6F5/2 (796 nm), 6F9/2 (1085 nm), 6F11/2 (1264 nm), 6H11/2 (1677 nm) and another four bands of Eu3+ assigned to 7F0 → 5L6 (393 nm) Meza-Rocha et al. (2017) [5],5D2 (464 nm), 7F6 (2097 nm), and 7F1 → 7F6 (2202 nm). It is also witnessed a broad band having electronic transition 1S0 → 1P1 is due to Bi3+ ions. Optical band gaps, nephelauxetic ratio, and bonding parameters are discussed by using optical absorption data. Eu3+ single doped glasses show five emission bands, with the n-UV excitation wavelength 393 nm, in which characteristic feature red emission (612 nm) is recognized with transition (Meza-Rocha et al., 2017 [5])D0 → 7F2. At the same time, Dy3+ single doped glasses illuminated with the excitation wavelength of 385 nm shows their known natural emissions blue (481 nm) and yellow (574 nm), having transitions 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 respectively. Emission for co-doped glasses Dy3+-Eu3+ are excited with the different selected ultraviolet wavelengths such as 464 nm, 392 nm, 385 nm, 363 nm, and 348 nm. It can be observed that tunable emission from both the ions (Dy3+, Eu3+) from orange reddish emission to white emission. The energy transfer from Dy3+ to Eu3+ is manifested by the quadrupole-quadrupole mechanism, which is confirmed by Inokuti-Hirayama (I H) modal based on lifetime decay curves. Also, the efficiencies and probabilities of energy transfer are determined based on the results of decay curves. The CIE color coordinates of DE1.0 glass with the excitation 348 nm gives x, y coordinates as (0.332, 0.342) which confers the good white emission. CCT value for this glass is around 5520 K shows that useful for cool WLED applications.

Ytterbium-doped nanocrystalline powders of yttrium aluminum garnet (YAG:Yb3+) with ytterbium content from 5 to 30 at.% have been prepared by the citrate sol–gel method. Phase composition, crystal structure and microstructure of the materials were studied by means of X-ray powder diffraction techniques using both laboratory and synchrotron radiation sources. The photoluminescence spectra and the photoluminescence decay kinetics of Yb3+ ions at room temperature were performed as well. It was revealed that materials calcined at lower (1000 °C) temperature possess a small amount of Yb3+ ions occupying the octahedral sites of Al3+ ions, whereas the materials calcined at 1200 °C form the proper (Y1−xYbx)3Al5O12 solid solution.

Spectral luminescence parameters of pure and Bi-doped YVO4 microcrystals with different bismuth content (from 0.1 to 20 wt%) are studied in the 4.2–500 K temperature range. The broad photoluminescence band peaked at 570 nm is caused by localized exciton, which is formed by the electronic transition from bismuth to vanadium states. The temperature dependence of luminescence decay kinetics provides additional evidence of the localized exciton luminescence of Bi-doped YVO4. Band structure calculations reveal location of bismuth 6s2 states above the top of valence band formed by 2p oxygen states by ∼0.4 eV.

The paper deals with the results of comparative study on time-resolved pulsed optically stimulated luminescence (TR-OSL) response of ceramic YAP:Mn materials prepared by different methods. In parti...

High pressure studies of monoclinic yttrium aluminum oxide single crystals (Y4Al2O9 -YAM) doped with Ce3+ ions grown by micro-pulling-down method are reported. The results of absorption measurements in the mid-infrared prove the existence of four different sites in which Ce3+ ions substitute Y ions, in accordance with the crystallographic structure of YAM. The lowest 5d level of Ce3+ is located very close to the bottom of the conduction band for two of four Ce3+ related centers at ambient pressure, which results in strong temperature quenching of their luminescence. Two other Ce3+ centers do not emit at ambient pressure since their 5d levels are resonant with the conduction band. Application of high pressure above 11 GPa restores their luminescence. Consequences of such energy structure of various Ce3+ sites in YAM for the Dorenbos theory are discussed. The bandgap energy of YAM is found to be 5.93 eV, which is the smallest out of the three yttrium aluminum oxides. High-pressure synchrotron angle dispersive x-ray diffraction and Raman scattering measurements identify a phase transition occurring at pressures between 8 and 11 GPa, which has martensitic character. The second phase transition to another structure (likely with hexagonal symmetry) occurs at a pressure around 16 GPa.

This work consists of studies on the influence of thermally resistant transition metal oxides (TMO) viz., Ta2O5, Nb2O5 and ZrO2 on orange emission and NIR emission (1.3 μm) of Pr3+ ions in zinc borate glasses. Glasses of the composition 40ZnO–2Ta2O5/2Nb2O5/2ZrO2–56B2O3: 2Pr2O3 were synthesized by melt quenching technique. Optical absorption (OA), photoluminescence (PL) emission (in the wavelength region 500–2500 nm at λexc = 443 nm) and decay profiles of the two of the prominent transitions viz., 3P0 → 3H6 and 1G4 → 3H5 of Pr3+ ions were recorded. The spectra were analysed using standard J–O calculations and various radiative parameters associated with prominent transitions were estimated. Intensity of PL bands exhibited substantial increase due to addition of Ta2O5, Nb2O5 and ZrO2 to the host glass. Among the three studied glasses, ZrO2 mixed glasses exhibited the highest luminescence output. All the radiative parameters including quantum efficiency are observed to be the largest for ZrO2 mixed glasses. The results of IR spectral studies were also used for the analysis of emission spectra. The analysis indicated the degree of structural variations in the vicinity of luminescent Pr3+ ions is different due to addition of different transition metal oxides and such variations are found to be responsible for the changes in the PL output. Since a substantial improvement of PL emission corresponding to 1G4 → 3H5 transition is observed due to the admixing of TMOs, these glasses may be considered as the favourable candidates for the applications in telecommunications. Additionally, the emission in the green spectral region (which is predicted to be feeble under normal conditions) in the PL spectrum of Pr3+ ions is also found to be considerably increased and it is attributed to the transfer of energy from ZnO to Pr3+ ions in this region.

The results of X-ray diffraction studies of the Gd(Mg

A. Luchechko gratefully acknowledges a grant from the Institute of Physics PAS for a research visit to the institute, while A.I. Popov has been supported by project LZP-2018/1-0214 from the Latvian Council of Science., The MgGa 2 O 4 ceramics co-doped with Mn 2+ and Eu 3+ ions were synthesized via a higherature solid-state reaction technique. The samples with various Eu 3+ concentrations were characterised using high-resolution photoluminescence (PL) spectroscopy. The PL spectra show weak matrix emission in a blue spectral region with dominant excitation band around 380 nm. Manganese ions are highly excited deeply in UV region and exhibit emission band peaked at 502 nm. The Eu 3+ ions show characteristic f-f excitation and emission lines. The energy transfer between host defects and activator ions was observed. Luminescence decay curves of Mn 2+ and Eu 3+ emission showed complex kinetics with both Eu 3+ -ion concentration and excitation wavelength changes., Latvian Council of Science LZP-2018/1-0214; Latvian–Ukrainian Joint Research Project LV-UA/2016/1,M/.8-2018; project DB/RIDER0117U004443; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

Zinc borate glasses doped with 2.0 mol% of Er2O3 and mixed with thermally resistant transition metal oxides viz., Ta2O5, Nb2O5 and ZrO2 were synthesized. Optical absorption and photoluminescence spectra and decay profiles of these glasses were recorded at ambient temperature. The spectra were characterized using Judd–Ofelt theory and various radiative parameters viz., transition probability, A, branching ratio, β, and the radiative lifetime, τ, of principal emission transitions of Er3+ ions in these glasses were evaluated. The results indicated a significant enhancement in the intensity of green emission (related to 4S3/2 → 4I15/2 transition) of Er3+ ions due to co-doping of the glass system with Ta2O5, Nb2O5 and ZrO2. Quantitative analysis of the results pointed out that ZrO2 is the most favorable oxide among the three co-dopants for achieving the highest quantum efficiency of green emission. Results were further analyzed based on the structural modifications taking place in the vicinity of Er3+ ions due to co-doping with Ta2O5, Nb2O5 and ZrO2 and the reasons for such improvement were identified by means of IR and Raman spectroscopy studies. Additionally, the 4S3/2 energy level of Er3+ ions (from which the green emission is originated) seemed to be additionally populated by the energy transfer from the excited state of ZnO and contributed to the amplification of green emission.

An influence of the rare earth ions (La, Er) concentration on the luminescent properties of Ga2S3-La2S3-Er2S3 glasses in the visible and near-infrared spectral region has been studied. The analysis of absorption spectra and luminescence allow understanding of the redistribution processes of radiation energy. The results suggest that favorable visible and near-IR luminescence of Er3+ ions can be further modified in Ga2S3-La2S3-Er2S3 chalcogenide glasses through the effect of doping concentration and modification of environment (rare earth ions of Lanthanum act as a network modifier) of the optically active ions by the matrices composition changes.

In order to evaluate the quantum efficiency and to establish the mechanism of down-conversion processes in Bi3+−Yb3+ and Ce3+−Yb3+ co-doped YAG (Y3Al5O12) and GGG (Gd3Al5O12) garnets, direct measurements of quantum yield (QY) were performed along with studies of photoluminescence (PL), photoluminescence excitation (PLE), and photoluminescence decay kinetics. The studied materials have been prepared either in the form of powders synthesized by the sol-gel method or single crystalline films grown by the liquid phase epitaxy method. Concentrations of Bi3+, Ce3+ and Yb3+ ions in the studied epitaxial films were estimated using X-ray diffraction and optical absorption techniques. The obtained results testify a non-cooperative energy transfer mechanism for the Ce3+–Yb3+ co-doped YAG with a conversion ratio (which should be 2.0 for an ideal quantum cutting mechanism) less than 1.0. At the same time, for Bi3+–Yb3+ co-doped YAG and GGG this conversion ratio was found to be close to 2.0, suggesting quantum cutting via cooperative energy transfer from one Bi3+ ion to two Yb3+ ions.

Photoluminescence characteristics of the undoped and Bi3+ - doped Ca3Ga2Ge3O12 garnets are investigated in the 4.2–500 K temperature range by the methods of steady-state and time-resolved spectroscopy. The Bi3+ ions substituting for Ca2+ ions in the garnet Ca3Ga2Ge3O12 and parasitic Ca5Ge3O11 phases are revealed by the X-ray diffraction method. Under excitation in the Bi3+ - related absorption band, the ultraviolet and visible emissions are observed in Ca3Ga2Ge3O12:Bi. The ultraviolet emission bands are ascribed to the radiative decay of the triplet relaxed excited state of Bi3+ ions having different nearest surroundings. A visible emission is found to arise from an exciton localized around a Bi3+ ion. The suggestion is made that the lowest-energy excited level of Bi3+ is located close to the bottom of the conduction band of Ca3Ga2Ge3O12. The mechanisms of the processes, resulting in the appearance of luminescence of the undoped and Bi3+ - doped Ca3Ga2Ge3O12 garnets, are discussed.

Direct measurements of external quantum yield (QY) were applied to down-converting phosphors of Y 4 Al 2 O 9 (YAM) co-doped with Bi 3+ and Yb 3+ . The QY measurements were combined with studies of photoluminescence (PL), photoluminescence excitation (PLE) and photoluminescence decay kinetics. It was found that the energy transfer occurs mainly from one of the four possible types of Bi 3+ centers in YAM, namely Bi 3+ (I), with excitation and emission maxima at 278 nm and 360 nm, respectively. The absolute QY measurements show large discrepancy between the measured quantum efficiencies of the UV to near-IR down-conversion process and the efficiencies estimated from the shortening of the Bi 3+ luminescence decay time. Results presented in the paper testify the conversion ratio (which should be 2.0 for an ideal quantum cutting mechanism) to be no more than 1.0 in the studied material.

The work devoted to the investigation of a new luminescent and scintillation material based on the single crystalline films (SCFs) of Tm 3−x Lu x AG:Ce garnet; x = 0–1.5, grown by LPE method from PbO based flux. The best scintillation properties are achieved for SCFs of Tm 1.5 Lu 1.5 Al 5 O 12 :Ce composition. We have found that direct Tm → Ce and backside Ce → Tm energy transfer processes are observed in Tm 1.5 Lu 1.5 Al 5 O 12 :Ce. Due to elimination of traps in the 300–450 °C range, the relatively fast scintillation decay is realized in highly doped Tm 1.5 Lu 1.5 Al 5 O 12 :Ce SCFs. For this reason, Tm doping can be considered as a suitable way for improvement of the scintillation efficiency in other Ce 3+ doped garnet compounds.

UV emitting scintillating screens based on single crystalline films (SCFs) of Lu3Al5−xGaxO12:Pr garnet have been developed by the liquid phase epitaxy (LPE) growth method onto Y3Al5O12 (YAG) substrates using a lead-free BaO based flux. The absorbance, luminescence and scintillation properties of these SCFs have been investigated depending on the Ga content in the x = 0–1.9 range. We have found that the absorption and luminescence spectra of Pr3+ ions as well as the scintillation light yield (LY) and decay kinetics of Lu3Al5−xGaxO12 SCFs are non-linearly affected by the gallium concentration x in the mentioned solid solution due to preference for the distribution of Ga3+ and Al3+ ions between the tetrahedral and octahedral positions of the garnet host, respectively. The best scintillation properties of Lu3Al5−xGaxO12:Pr SCFs are achieved at the Ga content in the x = 1.0–1.2 range. The LY of the Lu3Ga1.2Al3.8O12:Pr SCF is comparable with the LY of the best reference LuAG:Pr single crystal counterpart and significantly (up to 3 times) overcomes the LY of LuAG:Pr and Lu3Al4–3.5Ga1.0–1.5O12 SCFs, grown onto the YAG substrates from the conventional PbO–B2O3 flux.

Photoluminescence characteristics of the undoped and Bi3+-doped lanthanide niobates are investigated by the steady-state and time-resolved spectroscopy methods in a wide temperature range of 4.2–500 K. The broad visible emission bands with the large Stokes shifts are found to arise from the triplet relaxed excited states characterized by a small (∼1 meV) spin-orbit splitting energy. This indicates the exciton-like origin of all the observed emission bands. The data allow to conclude that the Bi3+-related triplet relaxed excited state is located inside the conduction band. No ultraviolet emission caused by the radiative decay of the triplet relaxed excited state of a Bi3+ ion is observed. The dependences of the emission intensity on the Bi3+ content indicate that the complex visible emission band of the Bi3+-doped niobates consists of two main, the higher-energy and the lower-energy, components arising from the excitons localized around the single Bi3+ ions and the {Bi3+ - Bi3+} dimers, respectively. The processes resulting in the appearance of the exciton-like emission under photoexcitation in the Bi3+-related absorption bands are discussed.

Detailed investigations of the spectroscopic properties of Cr3+ ions in β-Ga2O3: 0.05% Cr3+ single crystals grown by the floating zone technique have been performed in the temperature range 4.5–550 K. The luminescence of Cr3+ ions at low temperatures is due to narrow R-lines (2E → 4A2 transitions) and their vibronic sidebands, whereas the broad intense band (4T2 → 4A2 transition) dominates at temperatures above 200 K. The vibronic sidebands of R-lines with amplitude of less than 5 % of the R1 line at a temperature of 4.5 K cover the region of 700-735 nm. The temperature dependencies of the luminescence intensity and the decay time of Cr3+ ions indicate the same mechanism of quenching of R-lines intensity and shortening of lifetime for 2E of Cr3+ ions. The temperature dependence of the R1-line decay time of β Ga2O3: Cr3+ with maximal temperature coefficient │Δτ/ΔT│ = 0.023 ms/K at 120 K and maximal specific sensivitity │(Δτ/ΔT)τ-1│ = 0.017 K-1 at 160 K indicates an application potential of this phosphor for low-temperature fluorescence thermometry.

The range of emission cross-section in RE3+ ions play a key role in developing optical systems with high performance. The present work focuses on mid infrared and visible emission properties of Er3+/Ho3+ions in sodium-sulfo lead phosphate (GExHy) glasses. The EDS, XRD and FTIR spectra were performed for basic structural analysis. Besides, DC (down-conversion) and UC (up-conversion), photoluminescence (PL) spectra of the prepared GExHy glasses pumped at 379 nm and 980 nm are investigated. The favourable concentration of Ho2O3 was estimated from the analysis of NIR PL spectra for Ho3+: 2.0 μm and Er3+: 1.5 μm. In GExHy glasses, the increase in intensity near 2.0 μm with decrease in intensity at 1.5 μm infers to energy transfer process between Er3+ and Ho3+ ions. The maximum energy transfer efficiency of GExHy samples is 75.5% and with the increase of Ho3+ ions, the lifetime decay has been reduced from 5.06 ms to 1.24 ms. The absorption and stimulated emission cross-section of Er3+:1.5 μm and Ho3+: 2.0 μm were calculated. Moreover, FWHM × σ emi was calculated for Ho3+:5I7→5I8 transition to estimate the probable MIR laser emission. The CIE color coordinates were estimated from both DC and UC PL spectra. All the results indicated that the prepared GExHy glasses have promising material applications in mid-infrared solid-state lasers and telecommunications.

This work is aimed at the determination of the preferential calcination conditions for maximum thermoluminescence (TL) and optically stimulated luminescence (OSL) emissions of europium doped zinc oxide (ZnO:Eu) pellets after exposure to β-particles when they are synthesized using the precipitation and sol-gel methods, in micro/nanoscales. The verification of the photoluminescence (PL) signals were investigated. The calcination temperature range of 800–1200 °C and the calcination times between 2 h and 24 h were applied in the production of ZnO:Eu pellets. The phase composition and morphology of the samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The transmittance measurements were carried out by Fourier transformed infrared (FTIR) spectroscopy to understand the vibrational properties of ZnO:Eu nanocrystals. In the XRD and SEM patterns, the formation of hexagonal wurtzite phase of ZnO was observed. It was observed that the samples exhibited a weak green emission when the excitation wavelength is 350 nm. In addition, the ZnO:Eu pellets exhibited two sharp peaks at 579 and 615 nm which related to the Eu transitions. The PL intensities dropped with the increasing calcination temperatures. The TL peaks settled at 130 and 300 °C with 5 oCs−1 heating rate, were found similar to each other when the pellets calcined using different temperatures and times. β-dose linearity extended from 1 Gy to 0.2 kGy for all of the studied samples.