Enhanced Radiation Resistance Research Articles

Strong nonlinear-polarization in ZnMgO epitaxial thin-films with Li incorporation

The second-order nonlinear-polarization originated from the interaction between thin-film materials with second-order nonlinear susceptibility (χ (2)) and high-power laser is essential for integrated optics and photonics. In this work, strong second-order nonlinear-polarization was found in a-axis oriented Zn1-x Mg x O (ZnMgO) epitaxial thin-films with Li incorporation, which were deposited by radio-frequency magnetron sputtering. Mg incorporation (x > 0.3) causes a sharp fall in the matrix element χ 33 of χ (2) tensor, although it widens optical bandgap (E opt). In contrast, moderate Li incorporation significantly improves χ 33 and resistance to high-power laser pulses with a little influence on E opt. In particular, a Zn0.67Mg0.33O:Li [Li/(Zn + Mg + Li) = 0.07] thin-film shows a |χ 33| of 36.1 pm V−1 under a peak power density (E p) of 81.2 GW cm−2, a resistance to laser pulses with E p of up to 124.9 GW cm−2, and an E opt of 3.95 eV. Compared to that of ZnO, these parameters increase by 37.8%, 53.4%, and 18.6%, respectively. Specially, the Zn0.67Mg0.33O:Li shows higher radiation resistance than a Mg-doped LiNbO3 crystal with a comparable E opt. First-principle calculations reveal the Li occupation at octahedral interstitial sites of wurtzite ZnO enhances radiation resistance by improving structural stability. X-ray photoelectron spectroscopy characterizations suggest moderate Li incorporation increases χ 33 via enhancing electronic polarization. These findings uncover the close relationship between the octahedra interstitial defects in wurtzite ZnMgO and its nonlinear-polarization behavior under the optical frequency electric field of high-power laser.

RUVBL1 ubiquitination by DTL promotes RUVBL1/2-β-catenin-mediated transcriptional regulation of NHEJ pathway and enhances radiation resistance in breast cancer

Radiotherapy effectiveness in breast cancer is limited by radioresistance. Nevertheless, the mechanisms behind radioresistance are not yet fully understood. RUVBL1 and RUVBL2, referred to as RUVBL1/2, are crucial AAA+ ATPases that act as co-chaperones and are connected to cancer. Our research revealed that RUVBL1, also known as pontin/TIP49, is excessively expressed in MMTV-PyMT mouse models undergoing radiotherapy, which is considered a murine spontaneous breast-tumor model. Our findings suggest that RUVBL1 enhances DNA damage repair and radioresistance in breast cancer cells both in vitro and in vivo. Mechanistically, we discovered that DTL, also known as CDT2 or DCAF2, which is a substrate adapter protein of CRL4, promotes the ubiquitination of RUVBL1 and facilitates its binding to RUVBL2 and transcription cofactor β-catenin. This interaction, in turn, attenuates its binding to acetyltransferase Tat-interacting protein 60 (TIP60), a comodulator of nuclear receptors. Subsequently, ubiquitinated RUVBL1 promotes the transcriptional regulation of RUVBL1/2-β-catenin on genes associated with the non-homologous end-joining (NHEJ) repair pathway. This process also attenuates TIP60-mediated H4K16 acetylation and the homologous recombination (HR) repair process. Expanding upon the prior study’s discoveries, we exhibited that the ubiquitination of RUVBL1 by DTL advances the interosculation of RUVBL1/2-β-catenin. And, it then regulates the transcription of NHEJ repair pathway protein. Resulting in an elevated resistance of breast cancer cells to radiation therapy. From the aforementioned, it is evident that targeting DTL-RUVBL1/2-β-catenin provides a potential radiosensitization approach when treating breast cancer.

Abstract 1383: Investigation of biological role and cytokine axis of cancer-associated fibroblast (CAF) in lung cancer brain metastasis

Abstract Background: Brain metastases (BM) are among the most lethal forms of cancer globally. Lung cancer BM are frequently encountered and are associated with poor prognosis, decreased survival rates, and therapeutic resistances. Cancer-associated fibroblasts (CAFs) have emerged as important players of the brain metastases tumor microenvironment (TME). Mechanistic roles of brain metastases CAFs (hBM-CAFs) in tumorigenesis and therapeutic resistances remain unclear. Material and Methods: In the present study, the patient's BM surgical sample was subjected to primary culture to isolate CAF. The hBM-CAF induced EMT and stemness phenotype was investigated by western blot. Biological role of hBM-CAF in tumorigenesis was evaluated using indirect co-culture method in vitro. FACS analysis was performed to investigate the changes in cisplatin cytotoxicity and radiation susceptibility of lung cancer cell lines when co-cultured with hBM-CAF. CX3CL1 and IL26 expression was confirmed by ELISA along with transcriptomic analysis of hBM-CAF. Molecular events were validated by using neutralizing CX3CL1 and IL26. The tumorigenicity and response to chemotoxicity of lung cancer cells were examined by co-injecting them with hBM-CAF in a mouse xenograft model. Results: Our experiments demonstrated that hBM-CAFs significantly enhanced EMT and stemness phenotype by upregulating transcription factor SNAIL1, TWIST1, Slug and CD133, CD44 respectively in lung cancer cells. We also observed that hBM-CAFs decreased cisplatin cytotoxicity and enhanced radiation resistance, as measured by FACS analysis of apoptotic cells. In vivo experiments using xenograft mouse models revealed that co-injection of lung cancer cells with hBM-CAFs led to faster tumor growth and increased cisplatin resistance. Transcriptomic analysis of hBM-CAFs revealed a distinct genomic signature compared to normal fibroblast (hNFs), with significant overexpression of IL26 and CX3CL1 genes in the hBM-CAFs secretome, as validated by ELISA. Moreover, we found that lung cancer cells expressed high levels of the IL26 receptor IL10Rβ and ILR20α, and CX3CL1 receptor CX3CR1. Our hBM-CAF significantly upregulated JAK-STAT3 and Akt-mTOR pathway. Eventually, we have confirmed that neutralizing IL26 and CX3CL1 inhibit phosphorylation of JAK-STAT3 and Akt-mTOR respectively and revoked the IL26-CX3CL1 induced EMT and stemness phenotype of lung cancer cells. Conclusion: Patient derived hBM-CAF promote aggressive phenotype of lung cancer cells by upregulating EMT and stemness transcriptome factors. Overexpression of IL26 and CX3CL1 cytokine led to the therapeutic resistance through JAK-STAT3 and Akt-mTOR signaling pathway respectively. Targeting IL26-CX3CL1 might be a novel therapeutic efficacy for lung cancer brain metastasis patients. Citation Format: Nah Ihm Kim, SM Abdus Salam, Eshrat Jahan, Eun-Jeong Ahn, Tae-Young Jung, Jae-Hyuk Lee, Joon Haeng Rhee, Sung Sun Kim, Kyung-Hwa Lee, Kyung-Sub Moon. Investigation of biological role and cytokine axis of cancer-associated fibroblast (CAF) in lung cancer brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1383.

Effect of Al related chemical short-range order on the irradiation resistance of Al0.5CoCrFeNi multi-principal element alloy: A molecular dynamics simulation

Multi-principal element alloys (MPEAs) have received much attention for future nuclear materials due to their exceptional radiation resistance. This work investigated the effect of Al related chemical short-range ordered (CSRO) which caused by its large atomic size in face-centered cubic (FCC) Al0.5CoCrFeNi alloy on its irradiation damage behavior through mixed molecular dynamics and Monte Carlo simulations. The calculation results indicate that the CSRO structure effectively suppresses the generation of point defects during irradiation in Al0.5CoCrFeNi alloy, and this inhibitory effect increases with increasing irradiation energy. The enhanced radiation resistance of CSRO alloy is attributed to the high vacancy formation energy, interstitial atom formation energy, and vacancy migration energy barrier of Al. Moreover, the Al atoms in CSRO alloy can also act as defect barriers, preventing the migration of vacancy defects; The formation energy of interstitial atoms in the CSRO alloy exhibits a strong element dependence, and there is a significant difference in the formation energy of interstitial atoms between different points, which strengthens the hysteresis diffusion effect of MPEAs and further enhances the radiation resistance of MPEAs.

Damage mechanism and mechanical properties of carbon nanotubes induced by He2+ ion irradiation: Molecular dynamics simulations and experiments

Carbon nanotubes (CNTs) are expected to play a pivotal role in future space device applications owing to their exceptional material properties. To ensure the reliability and safety of CNTs in such applications, meticulous assessment and understanding of their structural integrity under ions irradiation is imperative. In this study, the mechanisms of damage to 1–5 wall CNTs caused by the irradiation of He2+ ions in the 1–100 keV energy range were investigated by conducting molecular dynamics (MD) simulations. The mechanisms of damage induced by He2+ ion irradiation exhibited notable distinctions between single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). SWCNTs easily conducted the kinetic energy of the He2+ irradiation out of the CNTs with cascade collisions, thereby reducing the damage they incurred, whereas the interlayer structure of the MWCNTs resulted in the irradiation energy being confined inside the tubes, leading to an increase in defects. The MD simulations revealed the irradiation swelling phenomenon of the MWCNTs in relation to the kinetic energy of irradiation and the cumulative fluence and indicated that swelling occurred simultaneously inward and outward along the radial direction of the CNTs. Irradiation-induced swelling was observed in experiments involving vertical array carbon nanotubes (VACNTs) irradiated with 540 keV He2+ ions. The results from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization, along with the Raman analysis, indicate that the damage observed in CNTs due to He2+ ion irradiation closely resembles the findings obtained through MD simulations. Both experimental and MD simulation studies demonstrated that increasing the dosage of He2+ ion irradiation increased the CNT defects, causing a transition from the ordered graphite structure to amorphous C. Additionally, the compressive mechanical properties and surface adhesion mechanics of the irradiated VACNTs were examined by performing nanoindentation experiments. The tensile mechanical properties of the irradiated CNTs were evaluated using MD simulations. The combined results indicated that high-energy, high-fluence ion irradiation degraded the mechanical properties of the CNTs. This study comprehensively investigated the mechanisms of damage to CNTs under He2+ ion irradiation and the subsequent impacts on the mechanical properties of the CNTs. The findings of this research provide essential insights for comprehending the irradiation responses of CNTs and for designing composite CNT materials with enhanced radiation resistance.

Effects of Thermal Boundary Resistance on Thermal Management of Gallium-Nitride-Based Semiconductor Devices: A Review.

Wide-bandgap gallium nitride (GaN)-based semiconductors offer significant advantages over traditional Si-based semiconductors in terms of high-power and high-frequency operations. As it has superior properties, such as high operating temperatures, high-frequency operation, high breakdown electric field, and enhanced radiation resistance, GaN is applied in various fields, such as power electronic devices, renewable energy systems, light-emitting diodes, and radio frequency (RF) electronic devices. For example, GaN-based high-electron-mobility transistors (HEMTs) are used widely in various applications, such as 5G cellular networks, satellite communication, and radar systems. When a current flows through the transistor channels during operation, the self-heating effect (SHE) deriving from joule heat generation causes a significant increase in the temperature. Increases in the channel temperature reduce the carrier mobility and cause a shift in the threshold voltage, resulting in significant performance degradation. Moreover, temperature increases cause substantial lifetime reductions. Accordingly, GaN-based HEMTs are operated at a low power, although they have demonstrated high RF output power potential. The SHE is expected to be even more important in future advanced technology designs, such as gate-all-around field-effect transistor (GAAFET) and three-dimensional (3D) IC architectures. Materials with high thermal conductivities, such as silicon carbide (SiC) and diamond, are good candidates as substrates for heat dissipation in GaN-based semiconductors. However, the thermal boundary resistance (TBR) of the GaN/substrate interface is a bottleneck for heat dissipation. This bottleneck should be reduced optimally to enable full employment of the high thermal conductivity of the substrates. Here, we comprehensively review the experimental and simulation studies that report TBRs in GaN-on-SiC and GaN-on-diamond devices. The effects of the growth methods, growth conditions, integration methods, and interlayer structures on the TBR are summarized. This study provides guidelines for decreasing the TBR for thermal management in the design and implementation of GaN-based semiconductor devices.

The AEG-1-USP10-PARP1 axis confers radioresistance in esophageal squamous cell carcinoma via facilitating homologous recombination-dependent DNA damage repair

Radiotherapy is the standard adjuvant treatment for esophageal squamous cell carcinoma (ESCC), yet radioresistance remains a major obstacle leading to treatment failure and unfavorable prognosis. Previous reports have demonstrated the involvement of astrocyte elevated gene-1 (AEG-1) in tumorigenesis and progression of multiple malignancies. Nevertheless, the precise role of AEG-1 in the radioresistance of ESCC remains elusive. Here, we unveiled a strong correlation between aberrant AEG-1 gene overexpression and malignant progression as well as adverse prognosis in ESCC patients. Moreover, both in vitro and in vivo investigations revealed that AEG-1 significantly alleviated irradiation-induced DNA damage and enhanced radiation resistance in ESCC cells. Mechanistically, AEG-1 recruited the deubiquitinase USP10 to remove the K48-linked polyubiquitin chains at the Lys425 of PARP1, thus preventing its proteasomal degradation. This orchestrated process facilitated homologous recombination-mediated DNA double-strand breaks (DSBs) repair, culminating in mitigated DNA damage and acquired radioresistance in ESCC cells. Notably, PARP1 overexpression reversed the radiosensitizing effect caused by AEG-1 deficiency. Collectively, these findings shed new light on the mechanism of ESCC radioresistance, providing potential therapeutic targets to enhance the efficacy of radiotherapy in ESCC.

Enhanced radiation resistance of W-based HEA under helium-ion irradiation conditions

Recently, high entropy alloy (HEA) has demonstrated superior radiation resistance to energetic particles. In this paper, we examine the radiation response of W-based HEA (WMoTaVNb) under the low-energy helium plasma exposure. As compared to pure W, WMoTaVNb demonstrated significant suppression in surface nanofuzz growth after the 65 eV helium plasma exposure to the same fluence (2 × 1024 He/m2). In addition, the 1 MeV helium ion implantation results present the sluggish helium bubble growth in W-based HEA, which is suspected to be the dominant cause to delay the nanofuzz growth. These results are further interpreted by comparing the transport of interstitial defects toward the surface regions in both pure W and W-based HEA via the molecular dynamic (MD) atomistic simulations. Our results show that due to chemical complexity, defect diffusion is highly localized in HEA, suggesting that the sluggish motion of interstitial defects may play another critical role in delaying surface nanofuzz growth if trap mutation and surface adatom formation mechanism dominates the fuzz growth.

Interaction of Stacking Faults with point/extended defects in Fe-He irradiated 6H-SiC

The study explored the microstructure evolution of 6H-SiC that underwent sequential iron and helium ion irradiation with energies of 2.5 MeV and 500 keV, respectively, at room temperature, followed by annealing at 1500°C for two hours. Following irradiation, the entire damaged layer underwent amorphization. However, during subsequent annealing, epitaxial recrystallization took place, resulting in the formation of defected polycrystalline 6H-SiC characterized by the presence of Fe-rich clusters, cavities, and stacking faults. Fe-rich cavities were found to predominantly form at the edges of the stacking faults, as revealed by XTEM. The interaction of microstructural defects is further investigated via first-principles calculations. The periphery of the stacking faults has been identified as the primary location for the emergence of vacancy clusters, serving as favorable sites for the accumulation of point defects, including Fe atoms. This behavior can be attributed to the combined effects of mechanical and electronic energy relaxation mechanisms. Mechanically, the presence of stacking faults allows for the release of elastic energy that had been stored at the boundary. Electronically, the energy relaxation arises from the saturation of C- and Si-dangling bonds. Both of these processes contribute to the observed behavior, highlighting the intricate interplay between mechanical and electronic factors in the system. The low point defect migration energy barriers in the vicinity of the stacking faults promise high recombination, which can limit cavity growth and enhance radiation resistance. The study not only offers valuable insights into the mechanism of cavity/stacking faults interaction, contributing to a better understanding of radiation damage in 6H-SiC but also demonstrates that 6H-SiC material containing stacking faults could serve as a viable alternative to 3C-SiC for nuclear application.

Radiation and electrostatic resistance for ultra-stable polymer composites reinforced with carbon fibers.

Future space travel needs ultra-lightweight and robust structural materials that can withstand extreme conditions with multiple entry points to orbit to ensure mission reliability. This is unattainable with current inorganic materials. Ultra-highly stable carbon fiber reinforced polymers (CFRPs) have shown susceptibility to environmental instabilities and electrostatic discharge, thereby limiting the full lightweight potential of CFRP. A more robust and improved CFRP is needed in order to improve space travel and structural engineering further. Here, we address these challenges and present a superlattice nano-barrier-enhanced CFRP with a density of ~3.18 g/cm3 that blends within the mechanical properties of the CFRP, thus becoming part of the composite itself. We demonstrate composites with enhanced radiation resistance coupled with electrical conductivity (3.2 × 10-8 ohm⋅m), while ensuring ultra-dimensionally stable physical properties even after temperature cycles from 77 to 573 K.

Spatial inhomogeneity of point defect properties in refractory multi-principal element alloy with short-range order: A first-principles study

Short-range order can be developed in multi-principal element alloys and influences the point defect behavior due to the large variation of the local chemical environment. The effect of short-range order on vacancy and interstitial formation energy and migration behavior was studied in body-centered cubic multi-principal element alloy NbZrTi by first-principles calculations. Two short-range order structures created by density functional theory and Monte Carlo method at 500 and 800 K were compared with the structure of random solid solution. Both vacancy and interstitial formation energies increase with the degree of short-range order. Point defect formation energies tend to be higher in regions enriched in Nb and lower in regions enriched in Zr and Ti. Both vacancies and interstitials prefer to migrate toward Zr,Ti-rich regions and away from Nb-rich regions, suggesting that Zr,Ti-rich regions can potentially act as recombination centers for point defect annihilation. Compared to an ideal random solid solution, the short-range order increases the spatial inhomogeneity of point defect energy landscape. Tuning the degree of short-range order by different processing techniques can be a viable strategy to optimize the point defect behavior to achieve enhanced radiation resistance in multi-principal element alloys.

Enhanced resistance to helium irradiations through unusual interaction between high-entropy-alloy and helium

Finding high performance plasma-facing materials (PFMs) is one of the most important and challenging tasks for realizing the commercial application of fusion reactors. Herein, we found the CrMoTaWV high entropy alloy (HEA) is highly resistant to low-energy and high-flux He plasma exposure. The nanochannel HEA film has 20 times higher initial fluence for the formation of fuzz and a remarkable 8.9 times slower fuzz growth rate than those of W. Combining the in-situ TEM observation and the Molecular dynamics (MD) simulation of the He bubble growth process, a new mechanism for the enhanced radiation resistance in HEA with the unusual interaction between HEA and He is found, where, differing from traditional metal, bubble growth in HEA leads to non-directional emission of interstitial atoms while HEA greatly suppress the growth of He bubbles. The special nanochannel structure further rise the radiation resistance through releasing He out of the HEA film and reducing the He concentration. This new nanochannel refractory HEA material presents a promising choice as the PFMs with excellent performance and a much longer serving lifetime for future commercial fusion reactors.

Local chemical ordering and its impact on radiation damage behavior of multi-principal element alloys

• LCOs promotes the nucleation of dislocations but inhibits their growth in the CrFeNi MPEA under irradiation. • LCOs reduces the number of stair-rod dislocation associated with SFTs, which may help to suppress irradiation swelling. • LCOs is conducive to enhance radiation damage tolerance of MPEAs. Multi-principal element alloys (MPEAs) have attracted much attention as future nuclear materials due to their extraordinary radiation resistances. In this work, we have elucidated the development of local chemical orderings (LCOs) and their influences on radiation damage behavior in the typical CrFeNi MPEA by hybrid-molecular dynamics and Monte Carlo simulations. It was found that considerable LCOs consisting of the Cr-Cr and Ni-Fe short-range orders existed in the ordered configuration with optimized system energy. Through modeling the accumulation cascades up to 1000 recoils, we revealed that the size of defect clusters and dislocation loops is smaller in the ordered configuration than those in the random one, although the former formed more Frenkel pairs (i.e., self-interstitials and vacancies). In addition, the distribution of dislocation loops is relatively more dispersed in the ordered configuration, and the stair-rod dislocations related to irradiation swelling are also smaller, implying that the existence of LCOs is conducive to enhancing radiation damage tolerance. To understand the underlying mechanism, the effects of LCOs on the formation and evolution of defects and radiation resistance were discussed from the aspects of atomic bonding, migration path, and energy of defect diffusion, which provides theoretical guidance for the design of MPEAs with enhanced radiation resistance.

Influence of Neutron Irradiation on Microstructure and Mechanical Properties of Coarse- and Ultrafine-Grained Titanium Grade 2

The influence of neutron irradiation on the microstructure and related mechanical properties of Ti Grade 2 in coarse- and ultrafine-grained conditions was investigated. It was found that mechanical properties of the coarse-grained (CG) state were significantly affected by neutron irradiation. At room temperature (RT), the yield stress increased by more than 30%, whereas the ductility decreased by more than 50%. An even bigger difference in the mechanical properties between irradiated and non-irradiated states was observed at a temperature of 300 °C. Changes in the mechanical properties can be attributed to the high density of defect clusters/dislocation loops induced by neutron irradiation. On the other hand, the ultrafine-grained (UFG) state is more resistant to radiation damage. The mechanical properties at RT did not change upon neutron radiation, while at a temperature of 300 °C, the yield stress increased only by about 10%. Enhanced radiation resistance of the UFG state can be attributed to the presence of a high density of dislocations and dense network of high-angle grain boundaries, which act as traps for radiation-induced defects and, thus, prevent the accumulation of these defects in the microstructure.

Simultaneous enhancement in hardness and He-irradiation tolerance of TiVCr/W medium entropy nanolaminates

In this work, we have studied the mechanical properties and He+ ion radiation resistance of TiVCr/W medium entropy nanolaminates with different individual layer thickness (h). The content of β-W decreases with the decreasing h, resulting in the hardness drop at first followed by a steep upturn. The maximum hardness reaches 10.79 GPa at h = 2.5 nm. After irradiation, the radiation hardening rapidly decreases with the reduced h, remaining zero hardening at h = 2.5 nm. The absorption of the He bubbles by the high-density interfaces and the suppression of radiation hardening by TiVCr layer result in the enhanced radiation resistance.

Heat treatment to regulate bismuth valence toward enhanced radiation resistance in barium gallo‐germanate glass

AbstractDue to the excellent infrared transparency, low phonon energy, and high rare‐earth solubility, germanate laser glass has attracted much attention in mid‐infrared fiber lasers for potential coherent laser radar systems, optical detection, remote sensing, and laser surgery. However, radiation‐induce darkening often occurs in fiber lasers that operate in radiation environment. Here, we report a useful strategy to improve the radiation resistance by adding multivalence Bi ions and discuss its radiation resistance mechanism. In order to study the effect of valence states on the radiation resistance of barium gallo‐germanate glass, we adjust the valence states of Bi ions by heat treatment, the potential mechanism of which is discussed in detail based on the absorption, photoluminescence (PL), and Raman spectra. The absorption, electron paramagnetic resonance, and photoluminescence spectra have proved the interconversion of Bi ions between low and high valence, which inhibits the formation of Ge‐related electron center (GEC) and non‐bridging oxygen hole center defects in the irradiation process. In addition, the Bi3+ content increased by heat treatment is beneficial to serve as electron‐trapping centers in γ‐ray irradiation, thus further reducing the formation of GEC. This study provides a simple method to achieve Bi valence regulation, so as to improve the radiation resistance.

In situ study on radiation response of a nanotwinned steel

Recent radiation studies on nanotwinned pure metals suggest that twin boundaries are appealing defect sinks, as they can transport and eliminate radiation-generated defects. However, radiation response of twin boundaries in nanotwinned steels is less well understood. Here, we investigate the microstructural evolution of a nanotwinned steel using in situ Kr++ irradiation to 4 dpa at ambient temperature. The in situ results show that nanoscale deformation twins in steels can effectively suppress the formation of ordered dislocation loop rafts. Furthermore, the formation of dislocation loop rafts and Frank loops depends prominently on twin spacing. The underlying mechanisms of the enhanced radiation resistance are discussed. The present study makes a positive step forward for the potential application of nanotwinned structural steels to nuclear reactors.

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.

Antimony-modified soda-lime-silica glass: Towards low-cost radiation-resistant materials

The development of inexpensive radiation-resistant glass is important for potential applications in displays, optics, and nuclear or space environments. This study considers the γ-ray and X-ray resistance of glasses relevant to low-cost float glass (i.e., SiO2–Na2O–CaO–MgO), modified with various concentrations (0 – 10 mol%) of Sb2O3. Various doses (0, 0.2, 2.0, and 5.0 MGy) of γ-rays from the decay of 60Co nuclei, and X-rays generated by an X-ray fluorescence (XRF) spectrometer, have been applied to this series of Sb2O3-modified float-type glasses to study their resistance to radiation-induced damage. Irradiation leads to the formation of various defect centres (HC2, HC1, TE, E', and E− types). These radiation-induced defects cause photo-darkening of the glass, which reduces its visible-wavelength optical transparency. The addition of Sb2O3 to these glasses led to reductions in the formation of radiation-induced defect-centres, combined with forbidden bandgap narrowing which led to non-linear changes in visible-wavelength absorption as a function of Sb2O3 content such that the most transparent irradiated glasses were advantageously obtained at low (0.5 mol%) Sb2O3 content. The mechanisms of defect-formation involve the creation of Sb4+-ions which assists in mitigating the effects of irradiation on the visible-wavelength transparency of the glass. The 0.5 mol% of Sb2O3-modified float glass provided a maximized concentration of Sb4+-ions upon γ-ray irradiation. Combined with the smallest changes in the UV band gap narrowing, it enabled this glass to retain the highest visible-wavelength transparency at all doses of ionizing radiation studied (0.2, 2 and 5 MGy). This work confirms the substantially enhanced radiation resistance of Sb2O3-modified float-type glasses compared to standard float glass, which could potentially be further developed towards commercialization, for example as a low-cost solution for radiation resistant applications.

Radiation resistance property of barium gallo-germanate glass doped by Nb2O5

Effects of Nb2O5 dopant on the radiation response of barium gallo-germanate (BGG) glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy. Owing to the Nb5+↔Nb3+ interconversion in doped samples, formations of Ge-related non-bridging oxygen hole center and Ge-related electron center defects after γ-ray irradiation are inhibited. Thereby, Nb2O5 dopant can enhance radiation resistance of BGG glass, and 1.0% Nb2O5 concentration is the best.