Γ-irradiated Glasses Research Articles

Physical properties and Raman spectroscopy inquiry of copper laden bio-relevant calcium phosphate glasses and the exposed to γ-irradiation

Pristine bio-relevant glasses of the P2O5-CaO-Na2O-CuO type where the [CuO]/[Na2O] molar ratios were varied at about 0.1, 0.7 and 1.5 have been scrutinized concerning fundamental physical properties and Raman spectroscopic features. Interpretations were assisted by X-ray photoelectron spectroscopy results regarding the chemical environments of oxygen, phosphorus, and copper. X-ray diffraction measurements performed using Mo-Kα radiation as X-ray source confirmed the amorphous character of the glasses, whereas differential scanning calorimetry showed rising glass transition temperatures with increasing copper content. The densities of the glasses increased linearly with CuO concentration whereas the molar volumes and phosphorus-phosphorus mean distances decreased. Raman results showed variation in the intensities, positions, and widths of main bands with increasing CuO concentration which was attributed to the impact of copper ions with high ionic field strength rather than a depolymerization effect. Finally, the Raman spectroscopy evaluation was extended to γ-irradiated (100 kGy) counterparts for a comparison with the pristine glasses. The γ-irradiated glasses however did not show significant changes in the Raman spectra thus supporting a lack of structural variation after the exposure to the ionizing radiation.

Effects of oxygen loading on the red-luminescence of non-bridging oxygen hole centers in γ-irradiated silica glasses

Ultra-high purity Corning 7980 and Corning 7979 silica glasses, respectively with high and low contents of hydroxyl and hydrogen, were specifically selected to investigate the effects of O2 loading on the 1.9 eV red luminescence of the gamma-ray induced non-bridging oxygen hole center (NBOHC), whose luminescence intensity is beneficial not only to predict the laser damage of silica but also to the targeted improvements in the preparation-treatment processes of silica. The UV trasmittance spectra, the UV excitation spectra, the visible emission spectra and the red emission lifetime decay curves were determined for these two types of the gamma-ray irradiated silica glasses before and after O2 loading. The content ratios of Si dangling bond (Si-E′) to NBOHC in silica glasses before and after O2 loading are estimated. The formation precursors and other related defects for NBOHC, such as Si-E′, Si-O-Si bond, Si-O-H bond, peroxy radical and linkage, oxygen-deficient centers ODC(I) and ODC(II), etc, are discussed. The bandwidths of the excitation and emission spectra before and after O2 loading are compared at the lower energy side of the spectra. The average emission lifetimes and especially the decay curves of the red luminescence before and after O2 loading are analyzed. There appear two types of NBOHCs with and without neighbouring hydrogen interaction at room temperature, respectively corresponding to the shorter and longer lifetime components. After O2 loading, the shorter lifetime component disappears and becomes the longer one, indicating that the hydrogen-bonded NBOHC is altered into the non-bonded. It is suggested that the analysis of the shorter and longer lifetime components of the red luminescence can be utilized in the laser damage prediction as well as the preparation and treatment processes of silica.

Alkali ionic state behavior in γ-Irradiated borate glasses for medical ultrasonic transducer fabrication

Lenses could be added to ultrasonic transducers used in medical applications to improve them. They may solve some limiting factors, like the acoustic impedance mismatch between the transducer and the tissues, the wave collimation difficulty, the wave scattering, etc. Novel ultrasonic transducers were developed that contained lenses made from new glass systems. Al2O3, MgO, and Li2O alkali-borate glass systems were prepared via the melt-quenching technique. Structural, electrical, and ultrasonic measurements were done with regard to the effect of gamma radiation. The XRD pattern showed the glassy, amorphous nature of the lenses. FTIR absorption spectra revealed the large stability of the main structural units of borate. Electron spin resonance (ESR) spectra clarified the low distortions caused by irradiation with g-values ∼ 2.025–2.026 and recognized the formation of oxygen hole centers (OHC) caused by breaking B–O connectivity. Al ions produced the most compact glass network, resulting in the highest ultrasonic velocity and wave passage. The characteristics of transducers with and without the lens were measured. The transducers with Al2O3 lenses demonstrated the lowest signal-to-noise ratio, the greatest beam diameter, and the highest sensitivity. The results ensured the effectiveness of the prepared glass as a lens in high-frequency ultrasonic transducers that are mainly used in medical applications.

In Situ Optical Microspectroscopy Study of Isothermal Bleaching of γ-Irradiated International Simple Glass.

The isothermal bleaching of γ-irradiated glass was studied at elevated temperatures (280-340 °C) by real-time in situ optical microspectroscopy for the first time. The study was performed on γ-irradiated (0.83 and 1.99 MGy) International Simple Glass (ISG) borosilicate nuclear waste simulant made by Mo-SCI Corporation (Rolla, MO, USA). The current investigation proposes real-time optical transmission methodology for the activation energy assessment of isothermal bleaching of γ-irradiated glass. The method is based on robust quantification of the Urbach energy decay rates and yields similar activation energies for both doses within ∼0.24-0.26 eV.

Physico-chemical properties of γ-irradiated International Simple Glass (ISG) nuclear waste simulants with low levels of iron impurities

The effect of γ-irradiation on physico-chemical properties of International Simple Glass (ISG) nuclear waste glass simulants with low iron impurities was investigated. The study was performed on glasses produced by Corning Inc. (named ISG-1, ISG-2) following a 0.95 MGy dose. Fourier-transform infrared and Raman spectroscopy, chemical durability tests, dilatometry, differential scanning calorimetry, electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopy appraisals were done in comparison with pristine glasses. The data indicated that structural, chemical, and thermal properties were not significantly altered following γ-ray exposure. EPR spectroscopy showed radiogenic signatures from spin defects for the γ-irradiated glasses which were absent in the pristine. Optical absorption also changed significantly for the γ-irradiated glasses which exhibited defects-related features around 3.45 and 2.25 eV. The optical band gap and Urbach energies were then determined and compared with those obtained for the γ-irradiated original ISG produced by Mo-SCI Corporation. PL spectroscopy revealed distinct changes after irradiation showing enhanced high-energy emission, contrasting with the γ-irradiated original ISG. The effects of thermal treatment on optical properties of γ-irradiated glasses were finally evaluated. Potential causes at the origin of the contrasting results are discussed based on the effects of different impurities.

Raman and optical spectroscopy study of iron-bearing bio-relevant phosphate glasses: Assessment of γ-ray irradiation effects

Glasses with 50P2O5-30CaO-(20 – x)Na2O-xFe2O3 (x = 0.1, 1, 5, 10 mol%) compositions were prepared by melting, and characterized by X-ray diffraction, Raman scattering, and optical spectroscopy. The glasses were subjected to γ-ray irradiation and structural and optical properties evaluated via Raman, absorption, and photoluminescence spectroscopy. The pristine glasses were X-ray amorphous, whereas Raman spectroscopy indicated Fe2O3 depolymerizes glass structure. Absorption spectroscopy showed that iron occurred largely as Fe3+ with Fe2+ revealed at high iron contents. Following γ-ray irradiation, the Raman features were preserved supporting lack of structural alteration. Radiation-induced defects were detected optically for 0.1 mol% Fe2O3 but prevented at higher concentrations. Bluish luminescence ascribed to electron centers was detected under 265 nm excitation for 0.1 mol% Fe2O3 similar to the irradiated host exhibiting ms-scale decay. The optical properties of γ-irradiated glasses at higher iron contents were like the pristine, supporting an increase in glass network resistance against gamma radiation.

Unveiling the gamma irradiation effects on linear and nonlinear optical properties of CeO2–Na2O–SrO–B2O3 glass

Herein, this work aims to unveil the gamma irradiation effects on the structural, linear and nonlinear optical properties of CeO2–Na2O–SrO–B2O3 (CSSB) glass. The CSSB glass system was prepared via the conventional melt annealing method and exposed to gamma irradiation with different doses (0, 2, 5, and 10) kGy. The XRD patterns confirmed the amorphous nature of the pristine and gamma-irradiated CSSB glass samples. Also, the observed FTIR spectra show almost no major changes in the absorption vibrational bands either in their positions or intensity with increasing the radiation dose indicating the stability of compacted CSSB glass structures and their radiation shielding effect due to the presence of cerium ions. Further, the energy gap decrease from 3.18 eV to 2.59 eV while the Urbach energy increased from 5.78 eV to 8.60 eV with increasing the irradiation doses. Furthermore, the dispersion constants and the dielectric constants as a function of the irradiation doses were estimated. This performance can be ascribed to the enrichment of charge carriers to polarization is restricted. Additionally, the reduction in the oscillator energy and the dispersion energy due to increase in γ-irradiation doses was seen. Furthermore, the non-linear absorption coefficient was enhanced for γ-irradiated CSSB glass films. Overall, the electronic polarizability of γ-irradiated CSSB glass films unveils the possibility of utilizing it in applications of optics and electronics. Besides, the prepared glasses have a remarkable reluctance against gamma irradiation make them promising materials in the radiation shielding utilizations.

“Effect of different 3d transition metal oxides on some physical properties of γ-Irradiated Bi2O3-B2O3 glasses: A comparative study”

Bismuth borate glasses of the basic composition 60 Bi2O3- 40 B2O3 doped with selected 3d transition metal TM oxides (0.7 wt. % of CoO, NiO or CuO) were prepared by the conventional melting- annealing method to avoid stresses and strains. Spectroscopic and physical properties of the prepared glasses before and after gamma irradiation (50 kGy) were investigated and interpreted such as UV-visible absorption, FTIR, ESR, density, oxygen packing density, molar and specific volumes. The glasses optical parameters, e.g. optical energy gap (Eopt), Urbach energy (Eu) and refractive index (n) were also calculated. The results indicated a good stability of the glasses towards irradiation because of the high content of heavy mass Bi3+ ions that participate as intermediate ions in the form of BiO3 and/or BiO6 units in the glassy network and the presence of 3d TM oxides which have ability to change their valence states and absorb the excited electrons.

Synthesis and characterization of γ-irradiated cadmium-borate glasses doped V2O5

In this work, we study the relationship between the optical and magnetic properties for the irradiated and unirradiated V2O5-doped cadmium borate glasses and examined their optical band energy that has compromise of non-bridging oxygen (NBO) and bridging oxygen (BO), V3+, V4+ and V5+, and BO3 units and BO4 units. The induced defects created by γ-rays were characterized by optical and EPR spectroscopy. The dependability of the defects and the tendency for recombination or conversion of the defects besides the environment of optically dynamic V centers was also discussed. It is concluded that the development of both optical and magnetic intensity is related to V4+ ions at tetrahedral sites whereas the decrease in their intensity is recognized to the ligand-metal charge transfer transitions of V4+ ions coupled to V5+. The optical band gap energy (Eg) has been observed to decrease with increasing either V2O5 content or γ-doses. High γ-dose reduces the values of the allowed direct optical band gap Eg of 0.5Mol% V2O5 glass up to 45kGy after which Eg increases, but remain lower than that of un-irradiated glass. Borate glasses under this study showed linear optical absorption response over the dose range of 5–80kG. Fading under dark and room light in 2h after exposure in the course of 30days have been studied in detail and presented. Our results and findings indicate that, the investigated samples may be seemed to be a good candidate for radiation processing purposes.

EPR of γ-induced defects and their effects on the photoluminescence in the glasses of the Ag0.05Ga0.05Ge0.95S2–Er2S3 system

Abstract Paramagnetic defects in erbium-doped γ-irradiated chalcogenide glasses were investigated by EPR method. Vacancy nature of defects and the dependence of their concentration on the irradiation dose and erbium content were determined. The measurement of the static magnetization revealed the presence of paramagnetic and ferromagnetic subsystems caused by isolated Er3+ ions and ion clusters, respectively. PL spectra of 4f–4f transitions of Er3+ ions and the radiation mechanism of γ-irradiated glasses were investigated. It was determined that PL intensity depends on the number of radiation induced defects and on the nature of the distribution of erbium which were determined by EPR and magnetic susceptibility.

A Ku band pulsed electron paramagnetic resonance spectrometer using an arbitrary waveform generator for quantum control experiments at millikelvin temperatures.

We present a 17 GHz (Ku band) arbitrary waveform pulsed electron paramagnetic resonance spectrometer for experiments down to millikelvin temperatures. The spectrometer is located at room temperature, while the resonator is placed either in a room temperature magnet or inside a cryogen-free dilution refrigerator; the operating temperature range of the dilution unit is from ca. 10 mK to 8 K. This combination provides the opportunity to perform quantum control experiments on electron spins in the pure-state regime. At 0.6 T, spin echo experiments were carried out using γ-irradiated quartz glass from 1 K to 12.3 mK. With decreasing temperatures, we observed an increase in spin echo signal intensities due to increasing spin polarizations, in accordance with theoretical predictions. Through experimental data fitting, thermal spin polarization at 100 mK was estimated to be at least 99%, which was almost pure state. Next, to demonstrate the ability to create arbitrary waveform pulses, we generate a shaped pulse by superposing three Gaussian pulses of different frequencies. The resulting pulse was able to selectively and coherently excite three different spin packets simultaneously-a useful ability for analyzing multi-spin system and for controlling a multi-qubit quantum computer. By applying this pulse to the inhomogeneously broadened sample, we obtain three well-resolved excitations at 8 K, 1 K, and 14 mK.

Investigation of physical ageing effect in Se 90 In 4 Sn 6 glass

Physical ageing effect in ternary Se90In4Sn6 glass has been detected, using differential scanning calorimeter (DSC), under the influence of Co60 γ-irradiation, natural storage, and both. The number of Lagrangian constraints per atom (nc) of the investigated Se90In4Sn6 glass comes out to be 2.9. This reveals that the studied material belongs to a floppy glass with under-constrained glassy network and hence one expects it to undergo physical ageing effect. It is observed that γ-irradiation increases the glass transition temperature Tg and the endothermic peak area A, which is directly related to the relaxation enthalpy loss. The estimated value of A of γ-irradiated glass is slightly higher than that of un-irradiated glass, indicating that thermodynamic equilibrium state of super-cooled liquid is still not reached and further storage is required. In addition, pure natural storage increases also the two ageing parameters (Tg and A) where the value of A is nearly four times greater than that of un-irradiated glass. This indicates that a significant natural ageing effect is evident in the studied glass and a structural relaxation process towards a more equilibrium state can be attained. Moreover, for γ-irradiated Se90In4Sn6 glass which has been aged for 8 years, a small increase in the A value is evident, which reveals that γ-irradiation modifies its covalent-bonded glass network towards thermodynamically equilibrium extrapolated states of super-cooled liquid.

Growth kinetics of AlOHC defects in γ-irradiated silica glasses

Electron paramagnetic resonance (EPR) measurements have been carried out on various types of natural fused silica (I301, Q310 and H102) irradiated with gamma-ray doses up to 14MGy. Paramagnetic defects E′γ as well as the non-bridging oxygen-hole centre (NBOHC), the peroxide radical (POR) and the aluminium oxygen-hole centre (AlOHC) account for all lines observed in the EPR spectra of irradiated samples. The growth kinetics of AlOHC has been followed and analysed. It is found that AlOHC defects are produced by two processes. One of them, called rapid process, saturates at low doses and has been related to the precursor {AlO4−/H+}, H+ acting as charge compensator. The second one, called slow process, takes place up to the highest dose and has been related to the precursor {AlO4−/M+}, the compensator M+ being an alkaline-earth ion Li+, Na+ or K+.

Effects of γ-irradiation and accelerated aging on composition-structure–property relationships for radiopaque embolic microspheres

Si–Ca–Zn–La–Ti–Mg–Sr–Na glasses have demonstrated excellent biocompatibility both in vitro using the MTT/LDH assays (with L929 mouse fibroblast cells and human blood platelets), and in vivo using New Zealand White rabbits. However, the biological evaluation of the materials was performed on as-manufactured glass granules that were autoclaved, rather than aged or γ-irradiated glass microspheres; the sterilization procedure required prior to implantation of these materials in its final form inside the human body. Given the fact that when a glass is subjected to aging either accelerated or natural changes in its physical properties can take place, it is imperative to determine whether the structure of such glasses will be altered over time in order to substantiate shelf-life claims. The structure of such glasses may also be altered as a result of exposure to the typical amounts of γ-irradiation required to sterilize such materials prior to implantation. This paper therefore examines the structure of Si–Ca–Zn–La–Ti–Mg–Sr–Na glasses using XRD, DSC, pycnometry, 29Si MAS-NMR and ICP–OES to evaluate both the effect of accelerated aging and multiple cycles of 30kGy γ-irradiation on their structure and subsequent radiopacity. The 29Si MAS-NMR results indicate that the peak maxima for each glass remain between −83ppm and −86ppm; a chemical shift for 29Si associated with Q2 to Q3 units in silicate glasses, and that the local environment around the 29Si isotope remains unaltered as a result of aging or exposure. Additional analysis (XRD, DSC, pycnometry, ICP–OES and radiopacity) showed that the glass transition temperature, Tg (676±4°C) typically remains unchanged, as a result of exposure to both accelerated aging and ionizing radiation, as do the density (3.63±0.02g/cm3) radiopacity (7049±847HU), chemical composition and XRD diffractograms for each glass. Therefore it can be concluded that the accelerated aging conditions tested herein or use of 30kGy γ-irradiation dose or subsequent effects does not affect the local environment of the 29Si isotope in the glasses, nor does it significantly alter the XRD diffraction patterns, chemical composition, Tg, density or the radiopacity values for the glass composition (0.562Si–0.035Ca–0.188Zn–0.068La–0.042Ti–0.035Mg–0.035Sr–0.035Na) described in this work.

Effect of gamma irradiation on some electrical properties and optical band gap of bulk Se92Sn8 chalcogenide glass

Abstract Some electrical properties and optical band gap of un-irradiated and gamma irradiated, at different doses of 4, 20 and 33 kGy, of bulk Se 92 Sn 8 glass have been studied. The I – V measurements, carried out in the temperature range of 187–296 K, have been done at different electric fields and exhibit an ohmic and a non-ohmic behavior at low and high fields, respectively, for both un-irradiated and γ-irradiated glass. In both cases, the conduction mechanism occurs due to Variable Range Hopping (VRH) of charge carriers in the localized states near Fermi level. As the γ-doses increase the amorphicity of the glass decreases, as monitored by the disorder parameter T o , and the density of states N ( E F ) increases up to 20 kGy after which a reverse in both parameters is observed. The increase in γ-doses increase the values of the allowed indirect optical band gap E g of Se 92 Sn 8 glass up to 20 kGy after which E g decreases but remain higher than that of un-irradiated glass.

The effect of gamma irradiation on glass transition temperature and thermal stability of Se 96Sn 4 chalcogenide glass

Se 96Sn 4 chalcogenide glass was prepared by melt quenching technique and exposed, at room temperature, to different doses of 4, 8, 12, 24 and 33 kGy of high-energy 60Co gamma irradiation. Differential scanning calorimeter (DSC) was used under non-isothermal condition to determine the glass transition temperature T g, onset T c and peak T p temperatures of crystallization, of un-irradiated and γ-irradiated samples, at four different heating rates. The variation of T g with heating rates was utilized to calculate the glass transition activation energy E t for un-irradiated and γ-irradiated glass, using the methods suggested by Kissinger and Moynihan. Based on the obtained values of the characteristic temperatures T g, T c and T p, thermal stability was monitored through the calculation of the S parameter and the crystallization rate factor 〈 K p〉 for irradiated and un-irradiated glass. Results reveal that, as γ-dose increases T g increases up to 12 kGy then decreases at higher doses but remains more than that of un-irradiated glass. Meanwhile, both E t and 〈 K p〉 attain their minimum values at the same dose of 12 kGy and the glass is thermally stable at this particular dose.

Physical ageing in Se 94Sn 6 glass induced by gamma irradiation

A differential scanning calorimeter (DSC) has been used to monitor the influence of high-energy Co 60 gamma-irradiation on physical ageing in Se 96Sn 4 glass. It is observed that the relaxation process in the studied glass is slow after 1 and 3 years of natural storage, and can be highly accelerated by γ-irradiation. The glass transition temperature T g and the endothermic peak area, which is directly related to the relaxation enthalpy Δ h, were found to exhibit a remarkable change after irradiation and also during an additional natural storage for 6 months and 1 year of the irradiated Se 96Sn 4 glass. T g value of γ-irradiated glass increases by 12 K; meanwhile, that of additional 6-months- and 1-year-stored glass T g increases by 19 and 20 K in comparison to its counterpart of 1-year-aged non-irradiated sample. The same trend is also observed for Δ h, which becomes 2.33, 3.61 and 3.65 times that of the 1-year-aged non-irradiated case, respectively, for γ-irradiated, additional 6-months- and 1-year-stored glass. These indications reveal that γ-irradiation activates the relaxation of the glass towards a state thermodynamically close to the equilibrium super-cooled liquid state.

Photoluminescence of oxygen-deficient-type defects in γ-irradiated silica glass

We studied the photoluminescence (PL) band in high-purity oxygen-deficient-type silicas both before and after high-dose γ-irradiation. With a high γ-irradiation dose of up to 10MGy, a new PL band was induce at 3.9eV and observed under excitation by 4.66eV photons, along with the previously observed 2.25, 2.7 and 4.3eV PL bands. Among the samples we investigated, this PL band was found only in high-dose γ-irradiated oxygen-deficient-type silica glass with the highest oxygen-deficient-associated defect structures [oxygen vacancy, E′ center and Eδ′ center]. These results indicate the possibility that this PL band is associated with an extreme oxygen-deficient-associated defect structure, at present unknown, in the silica glass which was introduced during the manufacturing process and which is enhanced by γ-irradiation.

Radiation-induced color centers in γ-irradiated glasses in the Na2O-Nb2O5-P2O5 system

The specific features of the induced optical absorption spectra of glasses in the 45Na2O · xNb2O5 · (55 − x)P2O5 system with Nb2O5 contents x = 5, 10, 20, 25, 30, and 35 mol % are investigated as functions of the irradiation dose and the heat treatment time. The spectra are decomposed into Gaussian components with the use of computer processing. It is revealed that the glass composition and the irradiation dose affect the number, type, and parameters of the bands associated with the PO 4 2− hole-type centers, electron-type color centers of the phosphate matrix, [Nb(5+)−] one-electron centers, and [Nb(5+)−-O-Nb(5+)−] two-electron centers. The inference is made that heat treatment at temperatures close to the glass transition point T g leads to the formation of groupings with a structure similar to structural motifs of NaNbO3 crystals. It is demonstrated that these groupings are responsible for the induced optical absorption in the near-IR spectral range.

06/00314 Alkali ion exchange in γ-irradiated glasses: Ojovan, M. I. and Lee, W. E. Journal of Nuclear Materials, 2004, 335,(3), 425–432

06/00314 Alkali ion exchange in γ-irradiated glasses: Ojovan, M. I. and Lee, W. E. Journal of Nuclear Materials, 2004, 335,(3), 425–432