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.     

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.     

Integration Between Optical and Structural Behavior of Heavy Metal Oxide Glasses Doped with Multiple Glass Formers

Heavy metal oxide glasses (composition 60 PbO, 20 Bi₂O₃ mol%) and containing 20 mol% conventional glass formers SiO₂, B₂O₃, and P₂O₅ were prepared. Combined optical and Fourier transform infrared absorption spectra were measured for the prepared glasses to justify the role of glass formers in the optical spectra together with the network structural groups in such glasses. Also, the density and molar volume values were calculated to obtain some insight on the compactness and arrangement in the network. Optical measurements have been used to determine the optical band gap (E_g), Urbach energy (ΔE) and the refractive index (n). Optical spectra of all the samples reveal strong UV absorption which is related to the presence of unavoidable trace iron impurities (Fe ³⁺ ions) contaminated within the raw materials which were used for the preparation of the studied glasses. Additional near visible bands are observed in all prepared glasses due to characteristic absorption of Pb ²⁺ and Bi ³⁺ ions. Furthermore, The variations of the luminescence intensity, values of the optical band gap, band tail, and refractive index can be understood and related in terms of the structural changes that take place in the glass samples. The infrared absorption spectra of the prepared glasses show characteristic absorption bands related to the borate or silicate or phosphate network (BO₃, BO₄, SiO₄, PO₄ groups) together with vibrational modes due to Bi-O and Pb-O groups.     

‘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.     

Synthesis and Spectral Properties of Nd<Subscript>2</Subscript>O<Subscript>3</Subscript>-Doped Sodium Silicophosphate Glass

Combined UV-visible and FTIR spectral studies of undoped and Nd₂O₃ –doped sodium silicophosphate glasses were carried out to characterize the optical and structural properties of such glasses. The base undoped silicophosphate glass exhibits strong UV absorption which is due to the presence of unavoidable trace iron impurities (mainly Fe³⁺ ions) present contaminated within the raw materials used for the preparation of such glasses. Nd₂O₃ –doped glasses show characteristic absorption bands extending in the entire visible region which are attributed to the contribution of Nd³⁺ ions with distinct peaks which are almost constant with the increase of dopant. This comes from the combined compact glass structure containing two glass forming units and the shielding of the rare-earth ions. Infrared absorption spectra of the studied glasses reveal characteristic IR bands due to the combination of both silicate and phosphate groups. The introduction of Nd₂O₃ within the dopant level (2 %) produces no variations in the IR vibrational bands due to the presence of the two structural silicate and phosphate groups giving compactness of the network structure. The deconvoluted spectra reveal the presence of phosphate groups in a slightly high ratio due to the high content of P₂O₅ in the composition.     

Spectroscopic Inquiry of the Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-role in Binary Sodium Borate,Sodium Silicate and Sodium Phosphate Glasses and Effects of Gamma Irradiation

Optical absorption spectral investigations have been carried out on Fe³⁺ ions doped sodium borate, sodium silicate and sodium phosphate glasses before and after gamma irradiation. The UV-visible absorption spectrum exhibits bands characteristic of Fe³⁺ ions coordination in each system. Interesting aspects of FT-IR spectra were found, and this gives information about the structure changes in the constituent units of these glass systems as a function of Fe₂O₃ concentration. All glasses reveal characteristic absorption bands due to the addition of different ratios of iron which explain the state of iron in each system in terms of its valence and coordination number. Results indicate that iron favors a higher oxidation state (tetrahedral coordination) in the case of sodium silicate glasses. The doping with progressive Fe₂O₃ additions (0.5?7.5 %) has some effect on the number and position of the characteristic bands due to formation of FeO₄ groups. The IR absorption spectra after irradiation reveal limited changes in the intensity which can be correlated with minor changes in bond angles and /or bond lengths within the structural units by irradiation.     

Shielding Behavior of Gamma-Irradiated MoO<Subscript>3</Subscript> or WO<Subscript>3</Subscript>-Doped Lead Phosphate Glasses Assessed by Optical and FT Infrared Absorption Spectral Measurements

Undoped and MoO₃- or WO₃- doped lead phosphate glasses were prepared by the melting-annealing technique. The glasses were characterized through UV-visible and infrared measurements which were repeated after gamma irradiation. Optical spectrum of binary lead phosphate glass shows distinct ultraviolet bands correlated with unavoidable trace iron impurities within the chemicals used for the preparation of the glasses. UV-visible absorption spectra of MoO₃- or WO₃- doped glasses exhibit additional UV-visible bands which are related to the presence of four oxidation states of the two transition metal (molybdenum or tungsten) ions (Mo³⁺, Mo⁴⁺, Mo⁵⁺, Mo⁶⁺, W³⁺, W⁴⁺, W⁵⁺, W⁶⁺). The extra UV band is related to hexavalent (5d⁰) state while the rest of the visible bands are related to (350–440 nm - trivalent state), (450, 550, 650 nm - tetravalent state) while the broad band centered at about 770 nm (pentavalent state). The intensities of the absorption bands are observed to change with the transition metal content and their valencies. Infrared absorption spectra reveal distinct vibrational bands which are assigned to phosphate groups with sharing of Pb-O vibrations within both the range 460–620 cm^-1 and the range 900–1100 cm^-1 revealing a compact network structure. Gamma irradiation causes a minor increase in intensity of one of the UV band due to suggested photo-oxidation of some trace ferrous ions to additional ferric ions but the remaining spectral curve remains unaffected which is obviously related to some shielding effects of heavy atomic weight of PbO. This heavy metal oxide (PbO) is assumed to retard or prohibit the free passage of free electrons or positive holes generated during the irradiation process.     

Ce3+‐ and Dy3+‐Doped Oxyfluoride Borosilicate Glasses with Near White Luminescence

A series of Ce³⁺/Dy³⁺‐doped oxyfluoride borosilicate glasses prepared by melt‐quenching method are investigated for light‐emitting diodes applications. These glasses are studied via X‐ray diffraction (XRD), optical absorption, photoluminescence (PL), color coordinate, and Fourier transform infrared (FT‐IR) spectra. We find that the absorption and emission bands of Ce³⁺ ions move to the longer wavelengths with increasing Ce³⁺ concentrations and decreasing B₂O₃ and Al₂O₃ contents in the glass compositions. We also discover the emission behavior of Ce³⁺ ions is dependent on the excitation wavelengths. The glass structure variations with changing glass compositions are examined using the FT‐IR spectra. The influence of glass network structure on the luminescence of Ce³⁺/Dy³⁺ codoped glasses is studied. Furthermore, the near‐ideal white light emission (color coordinate x = 0.32, y = 0.32) from the Ce³⁺/Dy³⁺ codoped glasses excited at 350 nm UV light is realized.     

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.     

Spectroscopic Studies and Luminescence Spectra of Dy<Subscript>2</Subscript>O<Subscript>3</Subscript> Doped Lead Phosphate Glasses

Dy^3 +-doped lead phosphate glasses were prepared by a melt quenching technique and investigated through Infrared absorption spectra (IR), photoluminescence (PL), and UV-Visible optical absorption measurements (UV-Vis). The luminescence spectra show two intense bands at 483 and 575 nm, which are attributed to ⁴FH_15/2 (blue) and ⁴FH_13/2 (yellow) transitions, respectively. The optical spectra data was used to evaluate the values of indirect allowed transitions. It was found that the optical band gap increases with Dy₂O₃ content. Variation in optical gap energy with the variation in localized state tails, confirms the theories for localized states in the energy gap of amorphous semiconductors. The characteristic infrared absorption bands of these glasses due to the stretching and bending vibrations were identified and analyzed by the increasing of the Dy₂O₃ content. This fact allowed us to identify the specific structural units which appear in these glasses.     

Properties of Bismuth-Containing High-Silica Glass Depending on the Bismuth Concentration and Heat Treatment. I. Spectral-Optical Properties

Bismuth-containing high-silica glass is synthesized by impregnating porous glass matrices in 0.01–0.5 M aqueous solutions of bismuth nitrate with the subsequent heat treatment at a temperature of 50–875°C. The dependences of the spectral-optical properties of the synthesized glass on the concentration of the doped bismuth (0.02–1.17 wt % Bi₂O₃) and heat treatment temperature are studied. It is found using the method of optical spectroscopy that bismuth is present in glass in different oxidation states—Bi³⁺, Bi²⁺, and \(\rm{Bi_5^{3+}}\) clusters. Near infrared spectroscopy in the 7500–4000 cm^–1 frequency range reveals that an increase in the temperature results in a gradual decrease in the intensity of the absorption bands due to the vibration of hydroxyl groups and water molecules adsorbed on the surface. The glasses (T ~ 50 and 400°C) exhibit bands at 4445–4443, 4433, and 4417–4415 cm^–1, which correspond to the absorption of Bi⁺ ions.     

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.     

Optical,FTIR and DC Conductivity of Soda Lime Silicate Glass Containing Cement Dust and Transition Metal Ions

Four soda lime silicate glass samples of composition (70 % SiO₂+ 20 % Na₂O+ 10 % CaO mol %) were prepared after adding 5 wt% cement dust to each sample mixture besides 0.1 wt% of one transition metal (TM) oxide of Fe, Co or Cu. The four samples were melted by a conventional melt-annealing technique at 1400 ^°C for 2.5 h. Density, UV/VIS, FTIR and DC conductivity measurements were performed for each glass. Experimental results indicate that there are only slight differences in the density values. The optical spectra reveal that the TM free sample and the sample containing iron ions have the same spectral features while the samples containing copper or cobalt exhibit distinct characteristic absorption bands due to each TM ion. FTIR spectra reveal characteristic vibrational bands due to stretching and bending modes of the silicate network. DC conductivity data show variations in the values of the studied samples according to the type of TM ions added. All the experimental results were correlated with each other in accordance with the current views on the constitution of the studied glasses.     

Mg3Y2Ge3O12:Bi3+ UV fluorescent phosphor as the TiO2 “sensitizer” for enhancing the heavy oil viscosity reduction

Nowadays, visible fluorescent materials based on rare earth (RE) and non-RE ions doping have been extensively explored for white LEDs. As for the UV fluorescent materials, it is well known that they are not suitable for the lighting applications. As a result, when compared to the visible fluorescent materials, previous works paid little attention to the UV fluorescent materials. In this work, we report a type of Mg₃Y₂Ge₃O₁₂:Bi³⁺ UV fluorescent phosphor. To understand the crystal structural information and photoluminescence (PL) properties of samples, we have used the X-ray diffraction (XRD), scanning electronic microscope (SEM), UV–visible diffuse reflectance and PL spectra to characterize them. The structural results reveal that the Bi³⁺ doped sample show their particle size at about 30 μm. The PL results show that the Bi³⁺ doped sample upon excitation at 230 nm can show a broad emission band that can almost cover the whole UV spectral region from 290 nm to 410 nm. Since this UV fluorescent band is exactly in agreement with the UV absorption region of TiO₂ semiconductor, we have fabricated several Mg₃Y₂Ge₃O₁₂:Bi³⁺/TiO₂-based ceramic plates and proposed used them to serve as an efficient UV irradiation source for photocatalytic application. As a result, we find that the TiO₂ can exhibit the significantly enhanced photocatalytic property for the heavy oil viscosity reduction after adding the Mg₃Y₂Ge₃O₁₂:Bi³⁺ UV fluorescent phosphor.     

Co-precipitation synthesis,band modulation and improved visible-light-driven photocatalysis of Te4+/Ti4+-codoped Bi3Nb17O47

Bismuth niobate semiconductors are of considerable interest in both contaminant degradation and H₂-generation. However, the wide band gap strictly limits the optical absorption in visible-light wavelength. In this work, a new niobate semiconductor Bi₃Nb₁₇O₄₇ was prepared with co-precipitation synthesis. To modify the band structure, Te⁴⁺-, Ti⁴⁺-, and Te⁴⁺/Ti⁴⁺-doping were conducted in Bi₃Nb₁₇O₄₇ lattices. Rietveld refinements were used to investigate the crystal phase and structure. The UV–vis absorption measurements concluded that Te⁴⁺-, Ti⁴⁺- doping could greatly modify the band energy of Bi₃Nb₁₇O₄₇. The Te⁴⁺/Ti⁴⁺-doped sample could harvest more visible light in the longer-wavelength region being favorable for photocatalysis performances. This was verified by RhB photodegradation tests under the visible-light irradiation (λ > 420 nm). To discuss the photocatalytic mechanisms, XPS and impedance spectra were measured. The improved photocatalysis was related to the microstructure changes, charge carrier dynamics, oxygen vacancies, and redox couples of multivalent ions. The present work provides a valid route to modify the band structure and to improve the photocatalysis abilities via impurity ions Te⁴⁺/Ti⁴⁺-doping in bismuth niobate semiconductors.     

Electron spin resonance and ultraviolet spectral analysis of UV‐irradiated PVA films filled with MnCl2 and CrF3

PVA films with various filling levels of CrF₃ and MnCl₂ were prepared. ESR and UV/VIS optical analysis were used to shed more light on the structural modification that occur due to filling with different levels and/or UV irradiation. The ESR analysis revealed that the spin configuration of CrF₃, MnCl₂, and CoBr₂‐filled PVA are different. The filling level dependence of ESR parameters was discussed. The UV‐VIS spectral analysis for pure PVA shows absorption bands at 265 and 280 nm, which were assigned to the presence of carbonyl groups. The addition of CrF₃ led to the appearance of another bands at 418 and 596 nm. The filling level and/or UV irradiation have no effect on the position of absorption bands but the intensity of these bands has been changed. The addition of MnCl₂ led to a new band at about 350 nm due to charge transfer transition. The ligand field parameters and optical energy gaps can be calculated and discussed. The results of optical and ESR analysis indicated that the Cr³⁺ or Mn²⁺ are present in its octahedral symmetrical form within the PVA Matrix. SEM micrographs of CrF₃ filled PVA is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 104–111, 2003     

LDPE/Bi2O3 nanocomposites: Enhanced mechanical,dielectric, and optical properties

This study is focused on investigating the role of bismuth oxide (Bi₂O₃) nanoparticles to improve structural, optical, electrical, and mechanical properties of low-density polyethylene (LDPE). For this purpose, Bi₂O₃ nanoparticles were synthesized by using the solvothermal method and examined by transmission electron microscopes (TEM), x-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–Vis) light absorption methods. LDPE-based nanocomposites were prepared by changing the nanoparticle additive ratio in the composite from 0% to 2% by weight. The composites were analyzed in the context of their FTIR spectra, atomic force microscope (AFM) images, UV–Vis light absorption spectra, stress–strain curves, and energy storage abilities. While the AFM findings indicate a smoother surface for the composites, the optical band gap analysis reveals a slightly decreased direct optical band gap energy. The analyses based on dielectric spectroscopy also highlight the LDPE/0.5% n-Bi₂O₃ composite in terms of the best energy storage capability. Additionally, the highest Young's modulus, toughness, stress at break, and percentage of strain at break were also recorded for the LDPE/0.5% n-Bi₂O₃ composite. In this context, the LDPE/0.5% n-Bi₂O₃ composite with improved dielectric and mechanical properties can be suggested as a new promising LDPE-based nanocomposite with better properties for industrial purposes.     

Spectroscopic properties of Er/Yb co-doped glass ceramics containing nanocrystalline Bi2ZnB2O7 for broadband near-infrared emission

Er/Yb co-doped transparent glass ceramics containing nanocrystalline Bi₂ZnB₂O₇ were successfully prepared by a high-temperature melting method. X-ray diffraction analysis confirmed the structural properties of the crystal and glass phases of the glass ceramics. Scanning electron microscope images indicated that nanocrystalline Bi₂ZnB₂O₇ with an average size of 30–40 nm was uniformly distributed in the glass matrix. Infrared spectroscopy demonstrated that the glass and glass ceramics had different vibrational peaks. The absorption spectra showed the absorption peaks of the samples, and the main spectral parameters of each absorption peak were calculated using the Judd–Ofelt theory. The emission spectra of the samples showed ultra-wideband fluorescence from 1400 to 1700 nm under excitation at 980 nm, which was enhanced by precipitation of nanocrystalline Bi₂ZnB₂O₇ and the addition of Yb³⁺ ions. Our research showed that Er/Yb co-doped glass ceramics containing nanocrystalline Bi₂ZnB₂O₇ are a promising material for application in near-infrared optical amplifiers.     

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.     

Effect of melting atmospheres on the optical property of radiation-hard fluorophosphate glass

High-energy radiation in space and nuclear irradiation environment induces colour centres in optical glass, causing solarisation, and a serious condition can render optical systems and optical loads unusable. To develop space radiation-resistant optical glass, CeO₂-stabilised radiation-hard fluorophosphate glass was prepared under three different atmospheres (nitrogen, oxygen, and ambient air). The glass-melting atmospheres' effects on the glass's transmission, defect formation, and structural changes before and after exposure to gamma radiation were investigated by a comprehensive study on their transmittance, absorption, and electron paramagnetic resonance spectra. Introducing a small amount of CeO₂ (～0.34 wt%) into the fluorophosphate base glass converted NBO and BO into ABO in the glass network, red-shifted the UV absorption edge, and decreased the optical density increment by almost half after radiation. As the total dose of gamma radiation increased, the transmittance of the irradiated glass at a wavelength of 385 nm significantly increased due to absorption of POHC2 defects. After exposure to 250 k of rad gamma irradiation, the corresponding optical density increment per centimeter thickness at 385 nm of the radiation-hard fluorophosphate glass that melted in the nitrogen, oxygen, and air atmospheres decreased from 1.839 to 1.388 and 1.215. As it melted in air, the NBO ratio of the fluorophosphate glass reached the lowest level and the Ce⁴⁺ ratio in the glass was 92.49%, which helped suppress the generation of POHC, Fe³⁺, PO₄-EC, and PO₃-EC defects during the gamma irradiation process, improving the glass's radiation resistance.