7F2 Transition Research Articles

Crystal Growth and Spectroscopy of Yb2+-Doped CsI Single Crystal

The single crystals of CsI-Yb2+ were grown, and their spectroscopic studies were conducted. The observed luminescence in CsI-Yb2+ is due to 5d–4f transitions in Yb2+ ions. Using time-resolved spectroscopy, spin-allowed and spin-forbidden radiative transitions of ytterbium ions at room temperature were found. The excitation spectra of Yb2+ luminescence bands were obtained in the range of 3–45 eV. The mechanism of charge compensation of Yb2+ ions in a CsI crystal was also studied, the spectrum of the thermally stimulated depolarization current was measured, and the activation energies of the two observed peaks were calculated. These peaks belong to impurity–vacancy complexes in two different positions. The charge compensation of Yb2+ occurs via cation vacancies in the nearest-neighbor and next-nearest-neighbor positions.The Yb2+ ions are promising dopants for CsI scintillators and X-ray phosphors in combination with SiPM photodetectors.

Efficient Ultraviolet Circularly Polarized Luminescence in Zero‐Dimensional Hybrid Cerium Bromides

AbstractUltraviolet circularly polarized luminescence (UV‐CPL) with high photon energy shows great potential in polarized light sources and stereoselective photopolymerization. However, developing luminescent materials with high UV‐CPL performance remains challenging. Here, we report a pair of rare earth Ce3+‐based zero‐dimensional (0D) chiral hybrid metal halides (HMHs), R/S‐(C14H24N2)2CeBr7, which exhibits characteristic UV emissions derived from the Ce 5d–4f transition. The compounds show simultaneously high photoluminescent quantum yields of (32–39)% and large luminescent dissymmetry factor (|glum|) values of (1.3–1.5)×10−2. Thus, the figures of merits of R/S‐(C14H24N2)2CeBr7 are calculated to be (4.5–5.8)×10−3, which are superior to the reported UV‐CPL emissive materials. Additionally, nearly 91 % of their PL intensities at 300 K can be well preserved at 380 K (LED operating temperature) without phase transition or decomposition, demonstrating the excellent structural and optical thermal stabilities of R/S‐(C14H24N2)2CeBr7. Based on these enantiomers, the fabricated UV‐emitting CP‐LEDs exhibit high polarization degrees of ±1.0 %. Notably, the UV‐CPL generated from the devices can significantly trigger the enantioselective photopolymerization of diacetylene with remarkable stereoselectivity, and consequently yield polymerized products with the anisotropy factors of circular dichroism (gCD) up to ±3.9×10−2, outperforming other UV‐CPL materials and demonstrating their great potential as UV‐polarized light sources.

Improvement of scintillation light yield of Tb:CaHfO3 by Mg-substitution

1.0 % Tb:Ca1-xMgxHfO3 (x = 0.05, 0.075, and 0.1) single crystals were synthesized by the floating zone technique, and their photoluminescence and scintillation properties were evaluated. The x = 0.1 sample showed the highest quantum yield of 18.7 % under excitation at 250 nm among all the samples. All the samples showed scintillation with multiple emission lines originating from the 4f–4f transitions of Tb3+. From the pulse height spectra, the highest light yield was 17,400 photons/MeV in the x = 0.075 sample among the samples, and all the samples outperformed the light yield of the unsubstituted one.

Integrating K+ into Eu and Tb doped GdCa4O(BO3)3: A dual study on photoluminescence and structure

In this study, we investigate the structural and photoluminescence (PL) properties of rare-earth-doped GdCa4O(BO3)3 (GdCOB) phosphors, specifically focusing on the spectral behaviour induced by doping with Eu³⁺ and Tb³⁺ ions. The powder X-ray diffraction (XRD) spectra confirm the formation of a monoclinic phase. The XRD data were also refined by a Rietveld refinement method. The existence of B, O, Ca, Gd, Tb, Eu and K elements was verified by EDS spectra. We introduce a detailed examination of the charge compensation process using Kröger-Vink notation to clarify the mechanisms essential for tailoring the optical properties of the phosphors. The PL excitation spectrum of GdCOB:Eu3+, monitored at 611 nm, reveals sharp excitation peaks at 319, 361, 380, and 392 nm, corresponding to 7F0→5H3, 7F0→5D4, 7F0→7F0, and 7F0→5L6 transitions, respectively. The PL spectrum under excitation of 392 nm exhibits that phosphors doped with Eu3+ a significant red emission at 611 nm, which is attributed to the 5D₀→7F₂ transition. This emission intensity is particularly enhanced at non-centrosymmetric sites of the Eu³⁺ ions. Similarly, the PL excitation spectrum of GdCOB:Tb3+, monitored at 552 nm, displays distinct excitation peaks at 316, 341, 353, and 379 nm, which correspond to the transitions 7F₆→5D₀, 7 F₆→5L₇, 7F₆→5D₂, and 7F₆→5D₃, respectively. Tb³⁺-doped phosphors display a bright green emission, with a dominant peak at 552 nm, resulting from the 5D₄→7F₅ transition. Additionally, the introduction of K⁺ ions as co-dopants results in modifications to the local environments of Eu³⁺ and Tb³⁺ ions. These changes allow for fine-tuning of the emission peaks, significantly enhancing the luminescent output of the phosphors. Optimal doping concentrations of 5 mol% for Eu³⁺ and 1 mol% for Tb³⁺ enhance luminescent intensity and prevent concentration quenching. This phenomenon, often resulting in reduced PL intensity at higher dopant levels, is primarily due to dipole-dipole interactions, consistent with Dexter's theory of energy transfer. Strategic modulation of doping concentrations, coupled with a deep understanding of energy transfer mechanisms are critical for the development of advanced luminescent materials Our analysis of the Commission de l′Eclairage (CIE) chromaticity coordinates reveals enhanced energy transfer dynamics in rare-earth-doped borates, facilitating the tuning of luminescent properties. These results not only deepen our understanding of the fundamental physics governing such phosphors but also open pathways for the development of optoelectronic applications requiring consistent color output, such as LED technologies and solid-state lighting.

Modification of Local Site Preference for Achieving Tunable Color Emission from Blue to Near-White in Sr3(PO4)2:Dy3+ Phosphor

The color tunability of Sr3(PO4)2:1%Dy3+ phosphor from blue to near white is studied at various annealing conditions. Higher temperature annealing promotes agglomerated rhombohedral (α) phase formation. Experimental and theoretical analysis reveal dopant preference at the low-symmetry Sr(II) site, altering electric (4F9/2→6H13/2) and magnetic (4F9/2→6H15/2) dipole transitions, thereby affecting the yellow-to-blue (Y/B) ratio. The luminescence intensity variation and color tunability are explained based on the local site symmetry and occupation probability of the dopant in the host lattice. An increase in the luminescence intensity up to an annealing temperature of 1200 °C, followed by quenching is observed due to the oxygen vacancies. Commission Internationale d'Eclairage (CIE) color coordinates of (0.31, 0.38), Correlated Color Temperature (CCT) of 6341 K, and color purity of 22.57% confirm the potential of Sr3(PO4)2:1%Dy3+ phosphor annealed at (1200 °C, 6 hrs) for white light generation. A probable photoluminescence mechanism involving 4f→5d→4f transitions in Sr3(PO4)2:1%Dy3+ is proposed.

Exploration of the optical characteristics in sol-gel synthesized europium-doped zinc oxide thin films for potential optoelectronic use: a comprehensive characterization approach

Abstract In this study, we present our findings on the spin coated pure Zinc-Oxide (ZnO) nanowire arrays and Europium doped ZnO (Eu3+: ZnO) nanostructure thin films. These arrays were grown on soda lime (silica) coated glass substrate. We conducted a comprehensive analysis of the structural and optical properties of the as-synthesized nanostructures. The characterization techniques included x-ray Diffraction, FESEM Analysis, Raman Spectroscopy, Photoluminescence and UV–vis Analysis. The XRD findings indicate the incorporation of Europium (Eu3+) into the ZnO crystalline lattice, potentially replacing Zn2+ ions. This doping with Europium (Eu3+) led to a reduction in crystalline size, as determined by Scherrer’s equation decreasing from 48 nm to 28 nm demonstrates a decrease in defects within the films. Raman Shift analysis revealed changes in the optical properties of films with inclusion of Europium in host matrix. Photoluminescence studies demonstrated a distinctive 5D0 to 7F2 transition arising from the Eu3+ ions, observed at approximately 612 nm. We have thoroughly examined the optical characteristics of both Europium-doped and pure ZnO thin films through a systematic study. The optical properties were assessed by analyzing the absorption spectra (220–600 nm) and transmission spectra within the wavelength range of 200 to 1200 nm. The film exhibited an impressive 80% transparency, particularly noteworthy for window layer application. The refractive index (n), extinction coefficient (k) and all other associated parameters were found to be impacted by the doping of Europium. The refractive index dispersion relation has been explored using a single oscillator model. Furthermore, the non-linear optical susceptibility (χ 3) and non-linear refractive index were computed using semi-empirical relationships based on the linear optical parameters. The Europium (Eu3+) doping in ZnO led to an increase in the χ 3 value elevating it from 4.07 × 10–1° to 5.91 × 10–1° e.s.u. These findings suggest that Europium-doped ZnO nanostructures have the potential to be a promising platform for the development of efficient multispectral light-emitting diodes (LED’s) and optical devices.

Structural and Spectroscopic properties of Eu3+ doped SiO2–TiO2 nanoparticles for photonic applications

The Eu3+-doped TiO2 nanoparticles in sol gel silicate glasses of composition (80-x)SiO2 + 20TiO2 + 0.5xEu2O3, (SiTiEu) where x = 0.0 0.5, 1.5, 2.5 and 3.5 mol%, have been prepared by sol-gel technique. The glass samples were investigated by thermos-gravimetric analysis (TGA/DTA), ATR-FTIR, XRD, SEM, TEM, EDX, optical absorption and photoluminescence emission spectroscopy at room temperature (RT). The absorption wavelength of TiO2 doped sol-gel silicate glass were red shifted due to a reduction in band gap energy with increasing annealing temperatures. According to the TEM images, all of the particles were spherical and had an average diameter is around 10 nm. The visible spectra of the Eu3+ doped TiO2 nanoparticles in sol-gel silicate glasses displayed characteristic PL emission 5D0→7FJ (J = 0, 1, 2, 3, 4, 5) transitions of Eu3+ ions at 370 nm excitation. The anatase TiO2:1.5Eu3+ nanocomposite showed high photoluminescence emission at 370 nm excitation, which was attributed to the f-f transitions of Eu3+. The hypersensitive 5D0→7F2 transition was responsible for the major red emission. From the recorded spectra, radiative parameters and Judd-Ofelt (JO) intensity parameters were computed. The Eu3+ co-doped TiO2 nanoparticles in sol-gel silicate glasses displayed emissions mostly in the red regions realized from a CIE chromaticity diagram. The results suggested that materials may be used as an optical material of technological importance such as display devices and also for optical amplifier.

Spectroscopic studies of Eu doped CaF2 single crystal

The Eu-doped CaF2 crystal is investigated for potential use in visible-region solid-state lasers. The single-crystal Eu: CaF2 has an FCC crystal structure and belongs to the space group Fm-3 m, as confirmed by single-crystal X-ray diffraction. A Raman shift of 324 cm−1 has been observed in a single crystal of Eu: CaF2. The vibrational mode at low frequency is suitable for minimizing non-radiative emissions and increasing radiative emissions. Eu: CaF2 crystal has two absorption bands, at 399 nm and 415 nm, corresponding to the 7F0→5L6 and 7F0→5D3 transitions, respectively. The strongest absorption peak (399 nm) is associated with the 7F0→5L6 electronic transition. The orange-red emission was observed at 588 nm (5D0→7F1), 612 nm (5D0→7F2), 648 (5D0→7F3), and 685(5D0→7F4) when excited at 399 nm. Measurements of the luminescence intensity ratio (R) between the 5D0→7F2 (electric dipole) transition and the 5D0→7F1 (magnetic dipole) transition predict that Eu3+ ions are situated at the symmetric sites in CaF2. The radiative parameters for the Eu: CaF2 crystal are calculated using the JOES code using the Judd-Ofelt theory. The calculated total radiative transition probability (AR) is 64.54 s−1, and the radiative lifetime (τR) is 15.57 ms. Radiative transition probabilities are 43.41,7.02 and 14.10, and branching ratios are 67.26 %,10.88 % and 21.85 % for 5D0→7F1, 5D0→7F25D0→7F4 transitions respectively.

Remote temperature sensing in microelectronics: optical thermometry using dual-center phosphors

Remote thermal sensing has emerged as a temperature detection technique for tasks in which standard contact thermometers cannot be used due to environment or dimension limitations. One of such challenging tasks is the measurement of temperature in microelectronics. Here, optical thermometry using co-doped and mixed dual-center Gd2O3:Tb3+/Eu3+ samples were realized. Ratiometric approach based on monitoring emission intensities of Tb3+ (5D4–7F5) and Eu3+ (5D0–7F2) transition provided sensing in the range of 30 °C–80 °C. Dispersion system type only slightly affected relative sensitivity, accuracy and precision. The applicability of phosphors synthesized to be utilized as remote optical thermometers for microelectronics has been proved with an example on a surface mount resistor and microcontroller.

Crystal Growth, Photoluminescence and Radioluminescence Properties of Ce3+-Doped Ba3Y(PO4)3 Crystal

Inorganic scintillation crystals have been widely used in applications of high-energy physics, nuclear medical imaging, industrial nondestructive inspection, etc. In this work, a single crystal Ba3Y(PO4)3 (BYP) with 1.0 at% Ce3+-doping concentration was first grown by the Czochralski method, and the electronic structure was calculated using first principles based on density functional theory. In addition, a series of Ce3+-doped BYP phosphors were synthesized, and the fluorescence emission under UV excitation was measured through low-temperature spectroscopy, containing double-peaked emission from 5d–4f transition and self-trapped exciton recombination. A comparison of the UV and X-ray-excited fluorescence spectra reveals the existence of oxygen vacancies as well as F+ centers in the crystal. The air annealing of the crystal effectively reduces the thermoluminescence defects but reduces the emission intensity under UV or X-ray excitation. The BYP:Ce crystal shows a fast decay lifetime of 15.5 ns, and the fast component is as short as 8 ns. The results show that the Ce3+-doped BYP crystal has potential as a kind of scintillator with fast decay properties.

HfTiO4 transparent thick film phosphors activated with Eu3+, Dy3+, and Tb3+ ions

Hafnium (Hf)-based double oxides show promise as high-efficiency scintillators due to large effective atomic numbers and high relative density. However, the preparation of these scintillation crystals is challenging due to their high melting points and incongruent melting behavior. In the present study, we demonstrated that the chemical vapor deposition (CVD) of single-phase HfTiO4 films on quartz glass substrate was successfully deposited at temperatures ranging from 973 to 988 K, with a TiO2 molar ratio in the precursor vapor of 25–45 mol% TiO2. The deposition rate of HfTiO4 reached 36 µm h−1. The films exhibited an in-line transmittance of 78 % relative to the raw glass substrate at a wavelength of 600 nm. When activated with Eu3+, Dy3+, and Tb3+ ions, the HfTiO4 films displayed red, yellow, and green photoluminescence emissions originated from the 4f–4f transitions of each trivalent rare-earth ion under ultraviolet light irradiation. HfTiO4 exhibited no intrinsic background emission, suggesting that the addition of a selected activator could yield a phosphor with the desired emission color range.

Coating Red Phosphor on Green Luminescent Material for Multi-Mode Luminescence and Advanced Anti-Counterfeit Applications

Traditional fluorescent anti-counterfeiting materials usually exhibit fixed-wavelength excitation patterns and monochromatic luminescence, which are extremely easy to be counterfeited and have low security. Therefore, there is an urgent need to develop multi-mode fluorescent materials with enhanced security to address this issue. Here, SrAl2O4:1%Eu,2%Dy@Y2O3:Eu3+ core-shell structured phosphors were prepared via a sol-gel method. Coating SrAl2O4:Eu,Dy with Y2O3:Eu3+ red phosphor did not significantly change the crystal structure of SrAl2O4. Under UV excitation at 254 nm, SrAl2O4:1%Eu,2%Dy@Y2O3:Eu3+ exhibited red emission at 613 nm (5D0→7F2 transition of Eu3+), and a strong green afterglow was observed after removing the UV irradiation. However, blue-green emission at 496 nm was observed under UV excitation at 365 nm, followed by green afterglow upon removal of the light source. Varying the content of the Y2O3:Eu3+ shell yielded different emissions and afterglows. The prepared samples are sensitive to the excitation wavelength and duration and have multimodal luminescence properties, which can be used for anti-counterfeiting patterns. The outcomes in this work indicate that the phosphor is a promising fluorescent material for anti-counterfeiting.

Optical and scintillation properties of Pr3+-doped (La, Y)2Si2O7 single crystals

Pr-doped scintillators are attracting attention because of their potential applications in medical devices. In this study, we focused on Pr-doped (La, Y)2Si2O7 scintillators to grow single crystals by the micro-pulling-down method and to evaluate their optical and scintillation properties. From the powder XRD results, the crystal structure and the space group were identified to be monoclinic and P21/n, respectively. The results of optical and scintillation characterization show that the luminescence from the Pr3+ 5d1–4f transition increases with increasing Pr3+ concentration. The maximum light yield was also obtained for the sample with the highest Pr3+ concentration. The Pr-doped (La, Y)2Si2O7 single crystal shows promising properties for application in radiation detection.

Investigation of structural, photo and thermoluminescence properties of YAGG:Ce nanogarnet for medical dosimetry application

Cerium-doped yttrium aluminum gallium garnet (YAGG:Ce3+) nanophosphors were synthesized using the sol-gel method. Mixed garnet of Y2.97Al5-xGaxO12:Ce0.03 was prepared with varying gallium content: x = 0, 1, 2 and 3 Ga. The effect of gallium substitutions on the structural, photo and thermoluminescence properties of the prepared nanophosphors were studied by X-ray diffraction (XRD), photoluminescence (PL) and thermoluminescence (TL) techniques. XRD results indicated that the single and pure cubic crystal phase was formed for all nanophosphor samples regardless of the Ga content. The PL spectra of all the samples exhibited a green-yellow emission band centered at 522 nm attributed to the 5d → 4f transitions of Ce3+ ions. The TL glow curve spectra recorded after β-particle irradiation showed a strong dependence in terms of position, shape and intensity, of all temperature peaks with the Ga content. The highest TL sensitivity was observed for the sample prepared with x = 2 Ga, with main peak arising at low temperature (85 °C). The sample prepared at x = 1 Ga exhibited also high TL sensitivity with a simple glow curve spectrum showing a main peak at high temperature (∼158 °C). Thus, the linear dose response of this sample has been investigated in the wide dose range from 0.125 to 100 Gy in order to evaluate the potentiality of this material for radiation dosimetry applications.

Lattice distortion effects induced by Li+ co-doping on ZnO:Tb3+ phosphors: Photoluminescence and unusual hypersensitive ⁵D₄ → ⁷F₀ transition

A series of Tb3+, Li+ co-doped ZnO phosphors were prepared using a precipitation method. X-ray diffraction (XRD) analysis indicated the successful incorporation of Tb3+ into the ZnO lattice. The influence of Tb3+ doping content and Li+ charge compensator on the photoluminescence (PL) properties of ZnO:Tb3+ was investigated. Under UV excitation, emissions corresponding to electron transitions 5D4→7FJ (J = 0,1,2,3,4,5,6) were observed from Tb3+ ions, including an unusual emission transition at 673 nm, which significantly enriches our understanding of Tb3+ luminescence. The critical concentration quenching of Tb3+ in ZnO:Tb3+ occurs at 7 mol%, as explained by the Van Uitert equation, which attributes this phenomenon to dipole-dipole interactions. Surprisingly, incorporating Li+ for charge balancing led to a reduction in the luminescence intensity of ZnO:7 mol%Tb3+, x%Li+ phosphors (x = 0.01 and 0.07) at 544 nm. This reduction highlights an increased degree of lattice distortion due to Li⁺ inclusion. Furthermore, CIE chromaticity analysis showed that the optimal doping concentration of 0.07 Tb³⁺ shifted the color coordinates towards vivid green, with a color temperature of approximately 6241 K, indicating of neutral white light.

Luminescent Ln3+-based silsesquioxanes with a β-diketonate antenna ligand: toward the design of efficient temperature sensors.

We report the synthesis and single-crystal X-ray diffraction, magnetic, and luminescence measurements of a novel family of luminescent cage-like tetranuclear silsesquioxanes (PhSiO1.5)8(LnO1.5)4(O)(C5H8O2)6(EtOH)2(CH3CN)2⋅2CH3CN (where Ln = Tb, 1; Tb/Eu, 2; and Gd, 3), featuring seven-coordinated lanthanide ions arranged in a one-capped trigonal prism geometry. Compounds 1 and 2 exhibit characteristic Tb3+ and Tb3+/Eu3+-related emissions, respectively, sensitized by the chelating antenna acetylacetonate (acac) ligands upon excitation in the UV and visible spectral regions. Compound 3 is used to assess the energies of the triplet states of the acac ligand. For compound 1, theoretical calculations on the intramolecular energy transfer and multiphonon rates indicate a thermal balance between the 5D4 Stark components, while the mixed Tb3+/Eu3+ analog 2, with a Tb:Eu ratio of 3:1, showcases intra-cluster Tb3+-to-Eu3+ energy transfer, calculated theoretically as a function of temperature. By utilizing the intensity ratio between the 5D4→7F5 (Tb3+) and 5D0→7F2 (Eu3+) transitions in the range 11-373K, we demonstrate the realization of a ratiometric luminescent thermometer with compound 2, operating in the range 11-373K with a maximum relative sensitivity of 2.0% K-1 at 373K. These findings highlight the potential of cage-like silsesquioxanes as versatile materials for optical sensing-enabled applications.

Impact of Eu3+/Tb3+ ions on PbO–NaF–B2O3 glasses optical absorption spectra

The optical characteristics of glasses have become an increasingly established and developing aspect. This article presents the optical characteristics of the Ln3+ ion in lead sodium fluoroborate glass, which has the composition 10 PbO–19 NaF–70 B2O3–1.0 Ln2O3 (where Ln=Eu and Tb, all in mol.%). Glass samples were processed using the conventional melt-quenched approach, and the glassy nature was confirmed by the X-ray diffraction patterns. The optical absorption spectra of PbO–NaF–B2O3 glasses with Eu3+ ions exhibit distinct absorption bands that were assigned to the transitions 7F05L6, 5D3, 5D2, and 7F15D1. Judd-Ofelt (JO) factors (2, 4, 6) were determined from the absorption spectra. By using least square fit analysis, oscillator strength (f) was evaluated and presented. Regarding the three J-O parameters (2, 4 and 6), 2, that is related to structural adjustments in the area of the Ln3+ ion, indicates slow adjustments of the covalent surroundings.

Growth and spectroscopic properties of Ca3(Ta,Ga)5O12:Pr3+ single crystal as a promising new laser material in the visible domain

Structurally disordered Pr3+-doped Ca3(Ta,Ga)5O12 - Pr:CTGG single crystal was grown by the Czochralski technique for the first time and its spectroscopic properties were investigated. Modified Judd-Ofelt analysis was applied to determine spectroscopic and laser emission characteristics. Based on low-temperature absorption and emission spectra, the partial energy levels of Pr3+ ions have been obtained and a multicenter structure of the optical spectra was highlighted. The electron-phonon interactions were also observed in the emission spectra corresponding to the 3P0 → 3H4 transition under different excitation wavelengths. The fluorescence decays of the 3P0 and 1D2 levels were measured. The emission cross-sections corresponding to the 3P0 → 3H4 (486.5 nm) and 3P0 → 3F2 (652.7 nm) transitions were found to be σem = 19 × 10−20 cm2 and σem = 15 × 10−20 cm2, respectively. The values for other parameters that may predict the possibility of achieving efficient laser emission, especially at 486.5 nm, such as quantum efficiency (ⴄ = 50 %), gain bandwidth (σem× Δλeff, = 32.2 × 10−26 cm3), and optical gain (σem× τmeas = 12.86 × 10−25 cm2 s) were determined. The obtained results indicate that the Pr:CTGG crystal has a high potential for obtaining efficient laser emission in the blue domain.

Photoluminescence and thermally stimulated luminescence properties of undoped and Tb-doped Sr3Gd(PO4)3 single crystals

Using the floating zone method, undoped and 0.5, 1, and 5% Tb-doped Sr3Gd(PO4)3 (SGPO) single crystals were synthesized. Investigations were conducted on the photoluminescence (PL) and thermally stimulated luminescence (TSL) of all the SGPO single crystals. The highest PL quantum yield was shown in the 5% Tb-doped single crystal among the synthesized SGPO single crystals. The undoped SGPO single crystal displayed an emission peak in both TSL and PL at 310 nm owing to the Gd3+ 4f–4f transition. In the Tb-doped SGPO single crystals, emission peaks in PL and TSL at 310–620 nm were caused by the 4f–4f transitions of Tb3+ in addition to Gd3+. In the TSL dose response function, the 1% Tb-doped SGPO single crystal exhibited the highest TSL intensity, and the TSL signal could be detected at least 0.01 mGy.

Physical and Optical Properties of CeF<sub>3</sub> Doped with Aluminium Fluorophosphate Glasses

Glass doped with cerium is an attractive material for a variety of applications. The aluminium fluorophosphate glasses were made by the conventional melt-quenching technique. The glass samples were characterized by density, refractive index, FTIR and photoluminescence spectra. The density was shown to increase, but refractive and molar volume were shown to decrease. The FTIR spectra of these glasses showed mainly [PO3] and [PO4] structural units. Transparency of the glass samples is demonstrated by a transmission intensity in the 70-80% range. Regarding the optical properties, under 307 nm excitation, the emission peak around 348 nm of the CeF3-doped aluminium fluorophosphate glasses was confirmed. The emission would be due to the 5d→4f transitions of Ce3+ ions.