Enhancement of the radiation resistance of cerium-containing fluorophosphate glasses through codoping with Sb2O3 and Bi2O3

The growing demand for radiation-resistant optical glasses for space and nuclear radiation applications has attracted significant research interest. However, radiation-resistant fluorophosphate glasses have been poorly studied. In this work, we report on the tailoring and performance of radiation-resistant fluorophosphate glasses that contained cerium through codoping with Sb₂O₃ and Bi₂O₃. The physical properties, optical properties, microstructure, and defects of fluorophosphate glasses were investigated using transmittance measurements, absorption measurements, as well as Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results showed that the radiation resistance of all codoped fluorophosphate glasses was better than the undoped cerium-containing fluorophosphate glasses after 10–250 krad(Si) irradiation. Especially in glasses doped with Bi₂O₃, the optical density increment at 385 nm was only 0.1482 after 250 krad(Si) irradiation. The CeO₂ prevented the development of phosphate-related oxygen hole center (POHC) defects, whereas further codoping with Bi₂O₃ suppressed the formation of oxygen hole center (OHC) and POEC defects, reducing the breaking of phosphate chains caused by CeO₂. Bi³⁺ is more likely than Sb³⁺ to change the valence, affecting the transition equilibrium of intrinsic defects and reducing the concentration of defects produced by irradiation. When codoping with Sb₂O₃ and Bi₂O₃, Bi₂O₃ does not enhance radiation resistance owing to the scission effect of Sb₂O₃ on the phosphate chain, which is not conducive to the radiation resistance of glasses. This indicates that the cerium-containing fluorophosphate glasses doped with Bi₂O₃ can effectively suppress the defects caused by irradiation and improve the radiation resistance of the glasses.     

Local environment of Eu3+ and Tb3+ ions in fluorophosphate glasses of the Ba(PO3)2-MgCaSrBaAl2F14 system

The induced optical absorption and EPR absorption spectra of fluorophosphate glasses of the compositions 40Ba(PO₃)₂ · 60MgCaSrBaAl₂F₁₄ and 5Ba(PO₃)₂ · 95MgCaSrBaAl₂F₁₄ doped with Tb³⁺ and Eu³⁺ ions are investigated within the model of the effective capture volume of free carriers. The concentration dependences of the relative number of radiation centers on the dopant concentration in fluorophosphate glasses are analyzed. It is established that the character of the distribution of dopant ions in glasses depends on the dopant concentration and the structure of the glass. The critical concentrations at which the oxygen local environment of Eu³⁺ or Tb³⁺ ions in the structure of fluorophosphate glasses transforms into a mixed local environment are determined for glasses of the compositions under investigation.     

Gamma rays Interactions with Bismuth Phosphate Glasses Doped with 3d Transition Metal Oxides

Bismuth phosphate glasses of the basic composition (Bi₂O₃ 30 mol%-P₂O₅ 70 mol%) with additional dopants 3d TM oxides (0.2 wt%) were prepared by the melting and annealing technique. Combined optical (UV/vis.) and FT infrared absorption spectra were measured for the prepared samples before and after gamma irradiation with a dose of 8 Mrad (8×10⁴ Gy). Optical spectra reveal strong UV absorption bands due to trace iron impurity together with an additional absorption band due to Bi³⁺ beside characteristic absorption related to specific 3d TM ions with preference for the lower valences due to the reducing effect of phosphate host glass. FTIR spectra show vibrational bands due to phosphate chains with the sharing of absorption bands due to Bi-O vibrations. Gamma irradiation causes limited changes due to the presence of heavy metal Bi³⁺ ions which show some shielding behavior towards gamma irradiation as revealed by optical and FT infrared absorption measurements. Some suggested photochemical reactions are forward to interpret the changes in the UV spectra beside the formation of an induced phosphorus oxygen hole center (POHC) in the visible region.

     

Evaluation of the optical changes for a soda-lime-silicate glass exposed to radiation

A soda-lime-silicate glass is exposed to beta radiation from an ⁹⁰Sr source and gamma radiation from a ⁶⁰Co source. Under exposure to radiation of the ⁹⁰Sr and ⁶⁰Co radioisotopes, the glass changes its color depending on the irradiation doses. The effect of beta irradiation on the optical properties of the glass is compared with that of gamma irradiation. The optical properties of the irradiated glasses differ significantly from those of the unirradiated glasses. Under exposure to beta and gamma radiation, the three main optical absorption bands appear at ～380–460, ～620, and ～1050 nm. It is established that the absorption band at ～420 nm, which is attributed to Fe³⁺ ions, is very sensitive to beta and gamma irradiation.     

Optical Absorption and EPR Studies on Gamma-Ray Irradiated RE<Superscript>3+</Superscript>-Doped Fluorophosphate Glasses

We have studied the effect of γ-ray irradiation on optical absorption, emission and decay characteristics of RE³⁺ (RE?=?Sm, Eu and Dy)-doped fluorophosphate glasses. Electron paramagnetic resonance (EPR) study confirms the POHC and PO₃ EC defects induced in glasses by the γ-irradiation. The presence of induced defect centers significantly affects the optical and emission properties. The optical band gap values of the studied systems increased after the γ-ray irradiation. The phonon energy and electron–phonon coupling strength of Eu³⁺-doped fluorophosphate glass were determined from the phonon sideband analysis. The emission intensity of the RE³⁺ ions increased significantly after the γ-ray irradiation. The intensity parameter, R is the ratio of the intensities of the ⁵D₀ → ⁷F₂/⁵D₀ → ⁷F₁ transitions of Eu³⁺ ion and Y/B intensity parameter is the ratio of intensities of the ⁴F_9/2 → ⁶H_13∕2/⁴F_9/2 → ⁶H_15/2 transitions of Dy³⁺ ion reveal that the local environment around the RE³⁺ ion changed after the γ-ray irradiation in the present system. The lifetime of excited states of RE³⁺ ions decreased after the γ-ray irradiation due to the formation of defects induced by the γ-ray irradiation. The CIE color coordinates were determined before and after the γ-ray irradiation for the Dy³⁺-doped glass system.     

Absorption Spectra and Bioactivity Behavior of Gamma Irradiated CeO2-Doped Bioglasses

The synthesis and characterization of some bioglasses based on Hench’s Bioglass® 45S5 with additions of CeO₂ (1.0, 2.0, or 3.0%) have been carried out. Two objectives have been focused upon; first, the effect of successive ionizing gamma irradiation on the undoped and CeO₂-doped bioglass samples has been evaluated with the aim of justifying the role of the rare earth oxide CeO₂ on gamma irradiation. The second objective was directed to test the bioactivity of such prepared CeO₂-doped samples after soaking for 1 month in a simulated body fluid at 37 °C. The results indicate that the additions of CeO₂ suppress, to a marked extent, the generation of radiation induced defects especially in the visible region. The bioactivity results show that the studied CeO₂-doped bioglass samples gave rise to a calcium phosphate surface layer upon immersion in a simulated body fluid for 1 month at 37 °C and the bioactivity extent was almost identical in the CeO₂ doping interval limit (1?→?3% CeO₂) to that of the undoped base Hench’s Bioglass. The presence of both Ce³⁺ and Ce⁴⁺ ions were confirmed by optical absorption spectra. Electron spin resonance (ESR) studies of gamma irradiated CeO₂-doped glasses indicate and confirm the dominance of Ce⁴⁺ in the bioglass compositions and its transformation to Ce³⁺ by high gamma irradiation.     

Enhancement of UV laser-induced damage resistance of the fluoride-containing phosphate glasses by regulating the intrinsic defects

Low fluorine content containing fluorophosphate glasses have promising potential as ultraviolet (UV) optics to be used in high-energy laser systems. Systematic studies on the iron-doped and iron-free fluoride-containing phosphate glasses that were prepared at high and low melting temperatures explore the underlying interrelationship among the glass preparation conditions, intrinsic defects in produced glasses, and the anti-laser-damage properties. For the iron-doped fundamental frequency (1ω) absorptive glass, melting at high-temperature (1200°C) can reduce the extrinsic “impurity” concentration of Fe³⁺ ions, resulting in tiny increase of optical bandgap (by 1.6%) but significant reduce of the absorption coefficient by 34% at 355 nm. However, only tiny increase of the laser-induced damage threshold (LIDT) was achieved. For the iron-free third harmonic frequency (3ω) transparent glass, low-temperature (1000°C) melting process significantly reduced the absorptive intrinsic defects content of PO₃-EC, PO₄-EC, and phosphorous oxygen-bonded hole center defects, which made the UV absorption edge blue-shifted by 50 nm and the optical bandgap increased by ∼18%. The UV (355 nm) LIDT was significantly enhanced by ∼27%. Much lower absorption coefficient and larger bandgap of the iron-free glass relative to the iron-doped one endow it with larger a LIDT. In short, optimizing the glass melting temperature is a feasible method to enhance the UV laser-induced damage resistance of the fluoride-containing phosphate glasses through controlling the content of the extrinsic or intrinsic defects in produced glasses. The general routine is to achieve both the lower UV absorptive defect concentration (i.e., lower UV absorption at 355 nm) and the lower non-bridged oxygen ratio (i.e., denser glass network), as well as a larger optical bandgap (i.e., reduced probability of avalanche ionization breakdown), which together contribute to the enhancement of the anti-laser-damage performance of the investigated fluoride-containing phosphate glasses.     

Radiation Resistance and Mechanical Stability of SiO2–BaO-Based Glass Coatings for Space Solar-Cell Panels

The influence of proton irradiation (energy, 18 MeV; beam current, 300 nA) with doses of 5 × 10¹⁴, 10¹⁵, and 5 × 10¹⁵ cm^–2 on samples of SiO₂–BaO-based glass coatings is investigated. The absorption, photoluminescence, and gamma luminescence spectra of the studied samples and their microhardness are measured. It is found that proton irradiation leads to a twofold increase in the microhardness. An insignificant increase in the optical absorption is revealed in the near-ultraviolet range (200–400 nm). This increase is accompanied by a decrease in the intensity of both light scattering in the wavelength range 400–900 nm and photoluminescence. The intensity of broadband gamma luminescence with a maximum at a wavelength of 500 nm increases with increasing proton irradiation dose. This means that excitonic radiative recombination impedes the formation of structural defects and their associated color centers. The combined effect of proton irradiation and solar electromagnetic radiation (gamma and visible light rays) accompanied by temperature changes in the range 80–470 K can provide an increase in the radiation resistance and mechanical stability of glass coatings used for solar-cell panels and their longer service life even under conditions of increased solar activity.     

Optical Properties and Effect of Gamma Irradiation on Bismuth Silicate Glasses Containing SrO, BaO or PbO

Optical and FT Infrared spectroscopic measurements have been utilized to investigate and characterize binary bismuth silicate glass together with derived samples by replacements of parts of the Bi₂O₃ by SrO, BaO, or PbO. This study aims to justify and compare the spectral and shielding behavior of the studied glasses containing heavy metal ions towards gamma irradiation. The study also aims to measure or calculate the optical energy band gap of these glasses. The replacements of parts of Bi₂O₃ by SrO, BaO or PbO caused some changes within the optical and infrared absorption spectra due to the different housing positions and physical properties of the respective divalent Sr2+, Ba2+, Pb2+ ions. The stability of both the optical and infrared spectra of the studied bismuth silicate glass and related samples towards gamma irradiation confirm some shielding behavior of the studied glasses and their suitability as radiation shielding candidates.     

‘Optical and FT Infrared Absorption Spectra of Soda Lime Silicate Glasses Containing nano Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> and Effects of Gamma Irradiation

The optical absorption spectra of undoped soda lime silicate glass together with two glasses doped with either (1 % nano Fe₂O₃ ) or with both (1 % Nano Fe₂O₃ + 5 % cement dust) have been measured from 200 to 2400 nm before and after gamma irradiation with a dose of 8 Mrad. The undoped glass reveals strong UV absorption with two distinct peaks which are attributed trace ferric iron ions present as impurity. Upon gamma irradiation , this base glass exhibits three peaks at 240,310 and 340 nm and the resolution of an induced broad visible band centered at 530 nm. The two doped glasses show an additional small visible band at about 440 nm and followed by a very broad band centered at 1050 nm. Upon gamma irradiation, the two doped samples reveal the decrease of the intensities of the spectrum. The two additional bands are related to ferric (Fe⁺³) ions to the band at (440 nm) while and the broad band at 1050 nm is due to ferrous iron (Fe⁺²) ions. The decrease of the intensities of the UV-visible spectrum upon irradiation can be related to of capturing freed electrons during irradiation . Infrared spectra of the glasses reveal repetitive characteristic absorption bands of silicate groups including bending modes of Si–O–Si or O–Si–O, symmetric stretching , antisymmetric stretching and some other peaks due to carbonate , molecular water , SiOH vibrations . Upon gamma irradiation, the IR spectra reveal a small change in the base spectrum while the IR spectra of the two doped glasses remain unchanged. The change of the IR spectrum of the base glass is related to suggested changes in the bond angles or bond lengths of the mid band structural units. The doped glasses show resistance to gamma irradiation because the nano Fe₂O₃ can capture released electrons and positive holes.     

Structural and Optical Properties of Lead-Boro-Tellurrite Glasses Induced by Gamma-Ray

Spectrophotometric studies of lead borotellurite glasses were carried out before and after gamma irradiation exposure. The increasing peak on the TeO₄ bi-pyramidal arrangement and TeO₃₊₁ (or distorted TeO₄) is due to augmentation of irradiation dose which is attributed to an increase in degree of disorder of the amorphous phase. The structures of lead tellurate contain Pb₃TeO₆ consisting of TeO₃ trigonal pyramid connected by PbO₄ tetragonal forming a three-dimensional network. The decrease of glass rigidity is due to irradiation process which is supported by the XRD diffractograms results. The decreasing values of absorption edge indicate that red shift effect occur after irradiation processes. A shift in the optical absorption edge attributed to an increase of the conjugation length. The values of optical band gap, E_opt were calculated and found to be dependent on the glass composition and radiation exposure. Generally, an increase and decrease in Urbach’s energy can be considered as being due to an increase in defects within glass network.     

The role of V<Subscript>2</Subscript>O<Subscript>5</Subscript> on the Structural and Optical Properties of MgO-ZnO-CdO-P<Subscript>2</Subscript>O<Subscript>5</Subscript> Glasses and the Impact of Gamma Irradiation

The quaternary glasses of mixed divalent oxides including ZnO, MgO, CdO within a phosphate network former were prepared. Vanadium pentoxide was introduced as a dopant in the range from 0.5 to 3%. Optical and infrared absorption studies for all glass samples were carried out. The optical spectra reveal the presence of both V³⁺ and V⁴⁺ ions in the studied host mixed divalent oxides phosphate glass. Fourier transform infrared absorption spectral analysis indicates the appearance of distinct vibrational bands due to the presence of characteristic phosphate groups depending on the glass composition and the ratio of V₂O₅ content. The optical band gap and Urbach energy were calculated and discussed in relation to the effect of V₂O₅ content. Finally, the glasses were optically and structurally examined affter gamma irradiation with a dose of 80 KGy.     

Effects of fluorinated substituents on the refractive index and optical radiation resistance of methacrylates

Novel fluorinated methacrylate polymers were synthesized. The purpose was to produce polymers with low refractive indices and increased resistance to optical radiation damage. Six different fluorinated substituents were appended on the monomer before polymerization. Optical-quality samples were prepared, and their transmission spectra, through 0.8 cm thick samples, were obtained. Each sample was tested for refractive index and glass transition temperature. The samples absorbed 10 MRad gamma radiation from a ⁶⁰Co source in an air environment; their transmission spectra were recorded immediately after irradiation and again after seven days had elapsed. As expected, increasing the fluorine content in the side chains resulted in decreased refractive indices. Fluorine content also influenced optical radiation stability. One polymer, poly(1H,1H-heptafluorobutyl methacrylate) retained superior UV/visible transmission after irradiation. © 1993 John Wiley & Sons, Inc.     

Optical,Spectral, and Radiation-Shielding Properties of High-Lead Phosphate Glasses

The spectral, optical, physicochemical, radiative, and radiation-shielding properties of glasses in the PbO-P₂O₅-R _m O _n system (where R _m O _n stands for Group I–V element oxides) are investigated as a function of their composition. The composition of a colorless radiation-resistant high-lead glass suitable for production on a semicommercial scale is determined. The properties and optical quality parameters of the glass are studied. The new phosphate glass is a lead metaphosphate containing aluminum, alkali, and alkaline-earth oxides. This glass is resistant to radiation at doses up to 10⁷ R and has an optical transmission edge at 360 nm. The coefficient of absorption of gamma radiation for the new glass is larger than those of dense silicate flints. According to the optical parameters, the new glass lies between dense flints and dense barium flints in the Abbe diagram and compensates for the absence of the latter flints in catalogues of radiation-resistant glasses.     

Effect of Gamma Irradiation on Structural and Optical Investigations of Borosilicate Glass Doped Yttrium Oxide

The structural, physical, and optical properties of prepared glass samples of the composition formula 30SiO₂-(40-x)B₂O₃-20Na₂O-10Al₂O₃-xY₂O₃, where x = 0, 1, 5, 7 (wt%) were studied before and after gamma irradiation using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-visible spectroscopy. The optical absorption spectra of study glasses were recorded in the UV/visible range of 200–900 nm. The optical band gap energies were calculated from absorption data. These results show that E_opt decreases with increasing concentration of Y₂O₃. The changes occurring in the optical parameters obtained from absorption spectra before and after irradiation have been referred to irradiation induced structural defects and compositional changes.     

Radiation effects of low refractive index,fluorinated methacrylate polymers for fiber cladding

The gamma radiation stability, optical properties, and mechanical properties of 1H, 1H, 3H-hexafluorobutyl and 1H, 1H-heptafluorobutyl methacrylate homopolymers and copolymers were determined and compared to poly(methyl methacrylate), PMMA. The aim of this study was to identify polymers for fiber cladding materials that exhibit improved optical radiation resistance and physical properties. Using ⁶⁰Co source, the samples absorbed 10 Mrads of gamma radiation at 0.04 Mrads/hr in an air environment. UV/Vis transmission spectra were obtained before irradiation, just after 10 Mrads, and regularly thereafter, to track recovery in transmittance. The glass transition temperatures, decomposition temperatures, refractive indices and flexural moduli were also obtained. Poly(heptafluorobutyl methacrylate) exhibited the greatest resistance to radiation induced discoloration and the lowest refractive index of the compositions tested. As the composition of the copolymers increased in hexafluorobutyl methacrylate concentration, both the radiation induced discoloration and the refractive index increased.     

Novel Synthesis of Low Hydroxyl Content Yb3+‐Doped Fluorophosphate Glasses with Long Fluorescence Lifetimes

A novel dehydration method for preparing rare‐earth ions‐doped fluorophosphate glasses was presented using raw materials soaking and rapid heating process, and a series of water‐free Yb³⁺‐doped fluorophosphate glasses (FPC) were obtained. In contrast with other dehydration methods, we found that the Yb³⁺‐doped FPC has wide transmission range and long fluorescence lifetime. The hydroxyl groups (‐OH) absorption was barely observed in the range 260–3750 nm, and the UV absorption cut‐off wavelength was blue shifted by 100 nm. Under the optimal conditions, the maximum value of emission cross section and the fluorescence lifetime of FPC reached 0.82 pm² and 2.67 ms, respectively. These excellent optical properties implied a potential application of the FPC glass in multicomponent glass fibers, IR lasers, and optical amplifiers.     

The effect of Nd3+ concentration on fabrication,microstructure, and luminescent properties of anisotropic S-FAP ceramics

Nd³⁺ doped strontium fluorophosphate (S-FAP), with chemical formula Sr₅(PO₄)₃F, nanopowders were prepared using the co-precipitation method. The prepared powders had no impurity phase with a grain size of about 30 nm and the doping limit of Nd³⁺ ions in strontium fluorophosphate is about 9 at.%. The morphology and particle size were determined by the doping concentration of Nd³⁺. Anisotropic Nd: S-FAP transparent ceramics with different Nd³⁺ doping concentrations were fabricated successfully by the simple hot-pressing method. The grain size of prepared S-FAP transparent ceramics decreased first and then increased with the increase of Nd³⁺ concentration. The 2 at.% Nd: S-FAP ceramic presented the highest optical transmittance at all wavelengths range. The characteristic transitions from the ground state to the excited states of Nd³⁺ ions were observed from the absorption spectra, and the absorption cross-section was calculated at 3.71 × 10^–20 cm². The influence of Nd³⁺ ion concentration on luminescence intensity and fluorescence lifetime was studied under 796 nm excitation. The strong emission of ⁴F_3/2→⁴I_9/2 transition in Nd: S-FAP was calculated by Judd–Ofelt (J-O) theory.     

Change of the properties of nanostructured MoO3 thin films using gamma-ray irradiation

Thin films of Molybdenum trioxide (MoO₃) were deposited on glass substrates by the spray pyrolysis at 500?°C and the samples were then exposed to gamma γ radiation doses by ⁶⁰Co radioisotope at different doses (0.1, 10 and 50 kGy). The effects of gamma irradiation on the properties of MoO3 thin films were investigated. The XRD pattern and Raman spectroscopy of as-deposited MoO₃ samples show an orthorhombic structure related to α-MoO₃ with (0k0) preferred orientations. Uv‐vis spectra were studied to investigate the transmission measurements of MoO₃ films. The optical energy band gap and Urbach energy were found to be gamma-dose dependent. Photoluminescence measurements at room temperature using 300?nm wavelength excitation were investigated. SEM images indicate the formation of α-MoO₃ nanorods.     

Effect of CoO and Gamma Irradiation on the Infrared Absorption Spectra of Lithium Borate Glasses

Undoped and cobalt-doped lithium borate glasses (LBG) of various compositions, by varying cobalt contents were prepared by a conventional melt quenching technique. The density and molar volumes of the glass samples were estimated and; infrared absorption spectra were measured in the spectral range 400–1600 cm^?1before and after an irradiation dose of 50 kGy and 200 kGy. Experimental results showed that the density of studied samples increased as CoO increased while the molar volume decreased. FT-IR spectra of the prepared samples have been analyzed by the deconvolution of the spectra. A deconvolution technique is presented to make use of the BO₄ data and follow the change in the modifier and former fractions of CoO. FTIR was also used to study the glass system before and after gamma irradiation. The experimental results clearly indicate that after irradiation a significant change in the structure of the LBG glass network is observed. The modifying action of CoO on the glass composition is also studied. The glasses doped with 5 wt% of CoO are relatively more radiation resistant than the other compositions.