Oxyfluoride Glass Research Articles

Enhanced scintillating performance in Tb3+ doped oxyfluoride glass for high-resolution X-ray imaging

Scintillators that exhibit excellent scintillation performance coupled with superior radiation resistance are anticipated to cater the growing demand of X-ray detection across various fields including medicine and scientific research. Oxyfluoride glasses, which combine the benefits of both fluorine and oxide glasses, show significant potential as scintillator candidates. Here, highly transparent Tb3+ doped oxyfluoride glasses with splendid radioluminescence were successfully synthesized by melt quenching method with the aid of a two-step component tuning strategy. The luminescence excited by X-ray and ultraviolet light are significantly enhanced by boosting the effective atomic number of glass components and optimizing the B2O3/Al2O3 ratio. The integrated X-ray excited luminescence intensity of representative specimen reaches 219% of that of BGO. Exceptional anti-irradiation recoverability and thermal stability of 93% @ 573 K are conferred in the resultant glass. Moreover, X-ray imaging with a spatial resolution of up to 20 lp mm−1 was triumphantly achieved. These properties testify that the prepared oxyfluoride glass owns an enormous application foreground in X-ray imaging.

Physical, thermal and radiation attenuation ability of Gd2O3 infused NaF - B2O3 - Bi2O3 - Sm2O3 glasses

In the present paper, 10NaF - (59-x)B2O3 - xGd2O3 - 30Bi2O3 - 1Sm2O3, where x = 0.0, 2.5, 5.0, 7.5 mol% glass system has been synthesized by melt quenching route. The density of G0.0 is 4.460 g/cm3 and reached 5.224 g/cm3 at the G7.5 sample with a molar surplus of Gd2O3. There is an increment in oxygen packing density (63.867 – 67.001 mol/cm3) and a decrement in oxygen molar volume (15.658 – 14.925 cm3/mol) discloses the tightly packed structure of the studied glasses. Moreover, enhancing field strength (1.346 – 1.523 × 1017 cm2) confirms the compactness of present oxyfluoride glasses. The linear attenuation coefficient and effective atomic number (Zeff) increase with the concentration of Gd2O3. The 7.5 mol% Gd2O3 doped glass sample exhibits a higher value of mass attenuation coefficient (MAC) as compared to the other reported glasses. The exposure buildup factor increases as the penetration depth of the material increases. Half value layer (HVL) and mean free path (MFP) decrease as Gd2O3 concentration increases in the glass network. The G7.5 glass demonstrates the lowest value in the half value layer and the highest value in the neutron removal cross-section. Therefore, prepared glasses show good performance in neutron and gamma-radiation shielding.

Tunable broadband luminescence of the novel Sn2+ doped oxyfluoride glass and glass-ceramics for W-LEDs

The demand for white-light luminescent materials for the white-light-emitting diodes (W-LEDs) field has been growing in modern life. In this work, a series of Sn2+ and Mn2+ ions co-doped highly transparent white-light emitting oxyfluoride glasses (precursor glass, PG) and Sr2LuF7 glass-ceramics (GC) were successfully prepared by the melt-quenching technique. Their luminescent and structural properties were investigated by the transmission spectra, excitation and emission spectra at different temperatures (300-500 K), luminescent decay curves, XRD, and TEM characterizations. Upon excitation with ultraviolet (UV) light, tunable broadband blue-white light emissions of Sn2+ were obtained by adjusting the concentration of Sn2+ ions. A conspicuous energy transfer process from Sn2+ to Mn2+ was observed in Sn2+/Mn2+ co-doped samples. Tunable broadband luminescence between blue-white light and orange-red light regions and nearly pink-white light emission was realized by varying Mn2+ concentration. Furthermore, compared to PG samples, the emissions were enhanced in GC samples due to the crystallization of Sr2LuF7 nanocrystals. Excellent thermal stability was also performed in these Sn2+ doped PG and GC samples with a recovering value of 96 % and 98.8 %, respectively. Simultaneously, Sn2+ doped PG and GC samples also own good optical thermal sensitivities with an SA value of 2.28 % and 2.47 % K-1, respectively. Our results indicate that these Sn2+/Mn2+ co-doped PG and GC may serve as tunable light sources under UV excitation and have prospects on the ratiometric optical thermometry fields.

High transparency Ce3+-doped oxyfluoride glass scintillator for X-ray imaging and γ-ray detection

High transparency Ce3+-doped dense gadolinium aluminum borosilicate (GSx) glass scintillator was synthesized in reducing atmosphere by melt-quenching process. The transmittance of the glasses exceeds 80%, and the light attenuation length is between 5-20 cm within the range of 400–600 nm. GSx glass shows an photoluminescence (PL) in range of 350–550 nm, with the strongest emission peak around 420 nm. The PL decay time of GSx glasses is around 37 ns, with a maximum PL quantum yield of 44.05%. The integrated X-ray excited luminescence (XEL) intensity of GSS glass is 52.5% compared with BGO crystal. For X-ray imaging, GSL glass based imaging system shows a high spatial resolution of 9 lp/mm, which is comparable to CsI:Tl X-ray detectors. Under γ-ray, the highest light yield of GSS glass is 1235 ph/MeV with an energy resolution of 24.0% at 662 keV, close to that of BSO crystal. The scintillation decay time of GSx glasses is consisted of fast (∼100 ns) and slow (∼560 ns) components. In thermally stimulated luminescence (TSL), GSS glass exhibits a strong TSL peak at approximately 440 K, with low intensity shoulders at about 520 K, implying different types of defects and traps. Therefore, GSx glass has promising prospects for X-ray imaging and high-energy physics applications.

Crystallization, structural, and optical properties of the 2BaF2·Al2O3·B2O3 glass in the presence of Er2O3 and SiO2

This study investigates the crystallization behavior and optical properties of the 2BaF2·Al2O3·B2O3 oxyfluoride glass in the presence of SiO2 and Er2O3 compositions. Samples were synthesized using the melt-quenching method. The amorphous nature of the prepared samples was characterized through X-ray diffraction (XRD) analysis. Differential thermal analysis (DTA) was subsequently employed to determine the glass transition temperature (Tg) and crystallization temperature (Tc). The presence of SiO2 and Er2O3 was found to enhance the glass forming ability and the crystallization temperature of the system. The optical bandgap was calculated by drawing Tauc plots from UV–Vis spectra. Notably, the presence of SiO2 caused a red-shift in the UV-absorbance edge of the glass, and resulting in a decrease in the optical bandgap. Molecular structure was further studied by Raman and FTIR analysis. Based on the DTA curves, glasses were heat-treated and the resulting glass-ceramics were analyzed using XRD, Photoluminescence and field emission scanning electron microscopy (FESEM). XRD analysis confirmed the crystallization of the BaAlBO3F2 crystalline phase within the glass matrix. Furthermore, the recorded down-shifted and upconversion photoluminescence spectra indicated that the Er3+ doped glass-ceramics have stronger emissions compared to glasses.

Tailoring Optical Properties of Rare‐Earth Doped Oxyfluoride Glass‐Ceramics by Tuning Crystal Structure

AbstractIt is known that oxyfluoride glasses can be used as the host for fluoride crystals that feature promising optical properties. This work demonstrates that the optical properties of the Er3+‐Yb3+ co‐doped oxyfluoride precursor glass‐ceramic (PGC) can be tailored by changing crystal structure through chemical variation (LaF3/BaF2 = 0, 1/3; YF3/LaF3 ratios = 0, 2/7, 4/7, 6/7, 1) and heat treatment. The strong correlations between the crystallization behavior, microstructure, and optical properties are revealed. It is found that the precipitated crystals such as BaF2, Ba2LaF7, Ba2‐xLa1‐xYxF7‐2x (0 < x <1), and BaYF5 are uniformly distributed in the glass matrices of PGC. Upon heat‐treatment, the crystallinity of PGC increases, whereas the crystal type remains unchanged. Both the up‐conversion luminescence and optical transmittance of the samples strongly depend on the substitution of one type of fluoride for another. Moreover, by taking advantage of the effect of crystal structure on the cross‐relaxation propensity of Er3+ ions, it is feasible to tune the up‐conversion luminescence color from green to light yellow. It is unveiled that the enhanced cross‐relaxation arises from lattice shrinkage. This work provides guidance for optimizing the optical properties of rare‐earth‐doped oxyfluoride glass ceramics.

Energy transfer and color tunability in high-thermal-stability Dy3+/Tb3+ co-doped K3YF6 transparent oxyfluoride glass ceramics

The production process and comprehensive analysis of the co-doping of Dy3+ and Tb3+ in K3YF6 oxyfluoride glass-ceramics (GCs) are delved. The primary focus is on investigating the luminescent properties and energy transfer (ET) mechanisms within these systems. The embedding of well-formed K3YF6 nanocrystals within the matrix was verified through detailed analyses using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Fine-tuning the Tb3+ concentration facilitated the achievement of tunable emission, ranging from a subtle yellow to a yellowish green hue, demonstrating the remarkable flexibility in color manipulation. Fluorescence analysis unmistakably demonstrates the occurrence of energy transfer occurring between Dy3+ and Tb3+ ions, attaining a peak energy transfer efficiency of 51.33 %. Additional analysis applying Dexter's energy transfer formula affirms that the fundamental mechanism of energy transfer between Dy3+ and Tb3+ ions is dipole-dipole interaction. The K3YF6 glass ceramics (GCs) incorporating Dy3+/Tb3+ nanocrystals exhibit a remarkable thermal stability, retaining 89.07 % of their original relative emission intensity at 423 K when stimulated by 350 nm light. These findings indicate that Dy3+/Tb3+ co-doped K3YF6 GCs hold significant potential in solid state lighting, positioning them as a candidate for future lighting.

Structural, optical and luminescent properties of Tm3+-doped phosphate oxyfluoride glasses for blue emission solid state devices

In this work, the visible luminescence of P2O5-KF-Al2O3 glasses with Tm2O3 was studied. The Tm3+ ion can have a strong blue emission, which allows the development of LEDs in this color region. This study refers to the synthesis of oxyfluorophosphate glasses, 38P2O5+(50-x)KF+12Al2O3+xTm2O3 (PKAl:Tm), with x = 0.25, 0.50, 0.75, and 1.00 mol%, by the melt-quenching method. The prepared materials showed amorphous characteristics verified by XRD data. The absorption spectra shown six main bands characteristic of Tm3+ ions, from ground state 3H6 to excited levels 3F4, 3H4, 3H5, 3F3,2, 1G4 and 1D2, in which the intensities increased with the concentration of Tm2O3. In the FTIR spectra, it was verified that the profiles of the PKAl samples are similar to glasses based on phosphate systems. The Judd-Ofelt parameters were calculated, where for PKAl glasses the trend was Ω2>Ω4>Ω6. The excitation spectra of PKAl:Tm glasses shown an intense band centered at 358 nm (3H6→1D2). The luminescence spectra with excitation at 358 nm shown two bands at 453 nm (1D2→3F4), and 480 nm (1G4→3H6); the highest emission intensity was observed to the sample doped with 0.75 mol% of Tm2O3. The calculated CIE diagram shown that the doped samples have coordinates close to the primary blue color, which favors the application for the development of blue LEDs and wLEDs. The decay curves for the 1D2 level were fitted by single exponential with lifetime values decreasing with increasing concentration of Tm2O3. These results show that the PKAl:Tm glasses are potential candidates for applications in LEDs.

Tunable luminescence in transparent oxyfluoride glass–ceramics containing KY3F10: Mn2+/Eu3+ nanocrystals for highly sensitive temperature sensing

Tunable luminescence in transparent oxyfluoride glass–ceramics containing KY3F10: Mn2+/Eu3+ nanocrystals for highly sensitive temperature sensing

Reduction mechanism and energy transfer between Eu3+ and Eu2+ in Eu-doped materials synthesized in air atmosphere

Abstract This article critically examines the reduction mechanisms and energy transfer processes between trivalent europium ions (Eu3+) and divalent europium ions (Eu2+) in materials synthesized in an air atmosphere. It also encompasses various materials and conditions, including a critical analysis of the reduction mechanism and energy transfer between Eu3+ and Eu2+ in Eu-doped materials. Specific investigations include exploring the reduction process in BaMgSiO4:Eu, focusing on factors influencing the reaction. The article also covers low-temperature self-reduction, addressing conditions and mechanisms such as the charge compensation model and laser-induced reduction. Additionally, it explores the influence of charge compensation on luminescent properties, emphasizing enhancements in red emission. Investigations into the role of oxygen vacancies in the reduction of Eu3+ and their implications on material properties are presented. This article further digs into abnormal reduction processes and the formation of defect centers in Eu3+-doped pollucite, proposing a substitution defect model for the self-reduction of europium ions in silicate Ba(Eu)MgSiO4 phosphors. Unusual reduction phenomena, such as reduction via boiling water in Yb2Si2O7:Eu3+ phosphors, and reductions in various glass systems, including porous glass, ZnO–B2O3–P2O5 glasses, aluminoborosilicate glasses, europium-doped Li2B4O7 glass, and aluminosilicate oxyfluoride glass (AOG), are also thoroughly examined.

Color tunability and temperature sensing capabilities in Dy3+/Sm3+ co-doped transparent oxyfluoride glass ceramics containing K3YF6 nanocrystals

This paper presents the preparation and characterization of transparent oxyfluoride glass ceramics (GCs) that contain nanocrystals of K3YF6 co-doped with Dy3+ and Sm3+. The study investigates the luminescence characteristics, the process of energy transfer (ET) and the behavior of the ratio-metric temperature sensing. The formation of well-defined nanocrystals of K3YF6 in the glass substrate was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). By varying Sm3+ concentration, a tunable emission ranging from pale yellow to orange-red was observed. Energy transfer from Dy3+ to Sm3+ ions was confirmed through fluorescence spectra and decay curves. Sample K3YF6, containing 0.5 mol%Dy3+/1.2 mol%Sm3+, showed an absolute sensitivity (Sa) of 0.635 % K−1 and relative sensitivity (Sr) of 0.401 % K−1. These findings underscore the promising applications of K3YF6: Dy3+, Sm3+ GCs in multicolor displays and high-performance temperature sensing devices.

Enhancing mechanical strength of Sr-based oxyfluoride glasses in glass ionomer cement through phase separation

Glass-ionomer cements (GICs) are used in various applications in clinical restorative dentistry. In this study the effect of CaF2 content of the glasses on microstructure, thermal and mechanical behaviors of the synthesized glass ionomer cements was investigated. The results showed that by adding CaF2 at expense of SrF2 the first exothermic temperature (TE) of the glass was reduced from 735 to 704 °C and the compressive strength was increased from 42.0 ± 1.29 MPa to 60.3 ± 1.5 MPa as well. These substitutions led to extending of liquid-liquid phase separation in the glass. The enhancement of mechanical properties demonstrated through the process of annealing glass powder at temperatures below half of the glass transition temperature. This technique contributes to the improvement of mechanical properties by decreasing the residual stress and fostering the separation of amorphous phases. The formation of phase separation appears to be a significant factor in improving the mechanical properties of the oxyfluoride cements.

Impact of aluminum fluoride addition on crystallization, structure and thermal properties of lead borate glasses

The glass composition (70-x)PbO–(30-y)B2O3–(x+y)AlF3, where x and y ranges from 0 to 20 mol%, were prepared using the conventional melt-quenching-annealing technique. The structural and thermal properties of the glasses were comprehensively analyzed using techniques like Differential Thermal Analysis (DTA), Dilatometry, Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). XRD confirmed the amorphous, non-crystalline structure of the glasses. The glass network was found to be composed of structural units such as PbO4, BO4, BO3 and AlO6 using FTIR spectroscopy. FTIR analysis revealed significant structural changes, including the transformation of BO4 to BO3 units and the increase in non-bridging bonds, particularly with higher AlF3 content. DTA was instrumental in determining characteristic temperatures, such as the glass transition, melting, and peak crystallization temperatures, along with glass stability parameters (∆T, Hr, Tgr) for all samples. The study found that the addition of AlF3 led to a decrease in these characteristic temperatures when replacing B2O3, but an increase when replacing PbO. Variations in the density and thermal expansion of the lead borate glass were observed upon the addition of AlF3, decreasing when substituting for PbO and increasing when substituting for B2O3. These findings provide insights into the properties of oxyfluoride glasses, paving the way for future optimization in their composition for varied applications.

Enhanced luminescence of Eu3+ doped β-PbF2 oxyfluoride glass ceramics for a new optical thermometry by charge compensation and local lattice symmetry breaking

Eu3+ doped β-PbF2 oxyfluoride glass ceramics (GCs) were synthesized via conventional melt-quenching method. The micro-morphology and luminescence properties of the fabricated GCs were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) spectra. A new temperature sensing mechanism based on fluorescence intensity ratio (FIR) between 5D0 → 7FJ (1, 2, 3, 4) and 5D0 → 7F0 transitions of Eu3+ ion was proposed. Such new mechanism is due to strong thermal coupling of 7FJ (J = 0, 1, 2, 3, 4) states because of their small energy gap. With the increase of temperature, more and more population reaches high states 7FJ (J = 1, 2, 3, 4) from 7F0 state through thermalization process leading to different temperature-dependent transitions of 5D0 → 7FJ (J = 0, 1, 2, 3, 4). Furthermore, lattice distortion around Eu3+ ions caused by co-doped K+ ions resulting in distinct enhancement of emission of Eu3+ ion and violent splitting of 7FJ (J = 2, 3, 4) states. Meanwhile, narrowing of energy gap between 7FJ (J = 0, 1, 2, 3, 4) states resulting from the violent splitting of 7FJ (J = 2, 3, 4) states facilitated thermalization process between 7FJ (J = 0, 1, 2, 3, 4) states and then enhanced sensitivity of temperature measurement was obtained. We believe that this preliminary study will provide an important advance in exploring other innovative optical thermometry.

Scintillation and photoluminescence performance of Ce3+-doped high gadolinium oxyfluoride glass for circular electron-positron collider (CEPC)

The large size (4 cm × 4 cm × 1 cm) Ce3+-doped high gadolinium oxyfluoride glass with density of 5.83 g/cm³ was prepared by the melt quench method at 1220 °C. The glass is colorless and transparent over the visible range. The prolonged decay time under 275 nm UV light demonstrates the energy transfer from Gd3+ ions to Ce3+ ions. The X-ray excited luminescence spectra (XEL) show the emission peak corresponds to the 5d→4f transitions of Ce3+ ion. The integral emission intensity of glass was compared with that of bismuth germanate oxide (BGO) crystals. The scintillation property of glass was studied under the γ-ray from 137Cs source and a clear energy peak was observed with light yield (LY) over 1100 ph/MeV. The scintillation decay time comprises fast and slow components. All results presented in this work indicate the appropriate potential to be high-energy rays detecting material for CEPC.

Phase-separation enhanced upconversion luminescence with regulated pure-red emission in manganese fluorosilicate glass

In this work, rare earth ions (REs) including Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+ co-doped manganese oxyfluoride glasses were fabricated using melt quenching method. By fully utilizing the upconversion luminescence (UCL) of REs and regulating energy transfer between the different energy levels of RE ions and the 4T1 level of Mn2+, the output of UCL was regulated and even pure-red light can be achieved. Moreover, owing to the selective partitioning caused by phase-separation network structure in the oxyfluoride glass, the UCL intensity of glasses annealed for 72 h is significantly enhanced 58 times compared to the rapidly quenched samples.

Color tunable emission and enhance green light emission in oxyfluoride glass ceramics containing Ce3+/Tb3+: Na5Y9F32 nanocrystals

Color tunable emission and enhance green light emission in oxyfluoride glass ceramics containing Ce3+/Tb3+: Na5Y9F32 nanocrystals

Optical properties and luminescence behavior of Tb3+-Doped SiO2–Al2O3–BaO–BaF2 oxyfluoride glasses and glass ceramics

In this study, oxyfluoride glasses with chemical composition of 45SiO2–15Al2O3–10BaO–30BaF2-xTbF3 (x = 0.2, 0.4 and 0.6 (mole ratios)) were prepared through the conventional melt-quenching method. Raman and FTIR spectra as well as molar volume calculations proved the creation of more non-bridging oxygens (NBOs) in presence of more TbF3 content. Accordingly, absorption edge in UV–Vis spectra showed a slight red-shift to longer wavelengths. The glass with 0.4 mol ratios of TbF3, exhibited the highest photoluminescence emission and its green-to-blue intensity ratio was 0.66. Therefore, this sample was chosen and heat treated at 630, 650 and 675 °C to prepare glass ceramic samples. For the sample heat treated at 650 °C, photoluminescence intensity increased and green-to-blue intensity ratio reached 0.69. Also, lifetimes of green and blue emissions increased from 3.35 ms to 3.67 ms and from 2.95 ms to 3.10 ms, respectively, when the base glass heat treated at 650 °C. Formation of BaF2 nanocrystals in glass ceramics moved the UV–Vis absorption edge to longer wavelengths significantly. Increment of the weak and dangling bonds in crystallized samples reduced Fermi energy, indirect and direct optical band gap energies from 3.792 eV to 3.301 eV, from 3.522 eV to 3.093 eV and from 4.095 eV to 3.582 eV respectively, which led to higher semiconducting behaviors.

Effect of Zn/Si ratio on conversion luminescent properties of Er3+/Yb3+ co-doped oxyfluoride glasses used for solar cells

Er3+/Yb3+ co-doped Na2O–CaF2–ZnO–Al2O3–SiO2 glasses with different Zn/Si ratios were prepared using the melt-quenching technique. The thermal stability was investigated by differential scanning calorimetry. Additionally, the absorption spectra were also analyzed to gather more information about their properties. The down-conversion luminescence corresponding to the strongest fluorescence at a wavelength of 547 nm was obtained under the 378 nm excitation, and a 4S3/2 level fluorescence lifetime was studied. By utilizing a laser pump with a wavelength of 980 nm, the process of both up-conversion and down-conversion luminescence was accomplished. In particular, the glasses substantially enhance fluorescence properties when the Zn/Si ratio is about 0.16. The changes in the Zn/Si ratio lead to modifications in the glass network structure, changing the coordination field environment around the fluorescence center and ultimately impacting the luminescence properties of the rare-earth ions. These effects are evidenced through the findings obtained from Fourier transform infrared spectroscopy and fluorescence spectroscopy analysis of the glass material.

Improvement in the photoluminescence property of Sm3+ activated oxyfluoride glasses on tailoring the crystal field with the incorporation of Gd2O3

Novel oxyfluoride glass having composition 10NaF- (59-x)B2O3- xGd2O3– 30Bi2O3- 1Sm2O3 has been synthesized by melt quenching approach. The amorphous nature of the glass was confirmed by the X-ray diffraction pattern. Raman and infrared spectroscopy confirm the presence of BO3, BO4 and BiO6 units. Photoluminescence studies suggest that the samples are capable of emitting intense light in the reddish-orange region. As Judd-Ofelt parameters follow the Ω4>Ω2>Ω6 trend, with improving asymmetry between Samarium ions and ligands. Additionally, the role of Gd2O3 on the emission spectra of Sm3+ is also witnessed in the X-ray luminescence emission spectra. The decay time measurement of the prepared glass samples is performed to explore the applicability of the samples in lighting devices. Further, the thermal sensing capability was examined by using a luminescence intensity ratio related to the two different electronic transitions. These results proposed that prepared glass can be used for lighting devices, temperature sensing and high-energy scintillators.