Candidate Glass Research Articles

Candidate glass–ceramic wasteforms for the immobilisation of Cs-loaded IONSIV® wastes: A scoping study

Candidate glass–ceramic wasteforms for the immobilisation of Cs-loaded IONSIV® wastes: A scoping study

Enhancement of the radiation shielding, physical and mechanical qualities of the Nd-glass series

The current study examines the physical, structural, mechanical, and radiation shielding properties of a series of (75-x) TeO2 -15 MgO -10Na2O -x Nd2O3: 0.0 <x < 2.0 mol% glasses. Nine distinct glasses coded as Nd-0.0 to Nd-2.0 are simulated via MCNPX Monte Carlo code by the varying composition of Nd2O3 (Neodymium oxide) and the related characteristics are evaluated between 0.015 and 10 MeV. The Beer-Lambert Law and Makishima–Mackenize theory are used to assess the preferred glass samples' radiation shielding and mechanical characteristics. Acquired results show that the Nd-2.0 glass sample gives the best gamma photon shielding performance. In addition, the computed physical features reveal that increasing the Nd2O3 contents from Nd-0.0 to Nd-2.0 leads to a tightly packed glass structure. Finally, it can be concluded that the candidate glass samples can be used as shielding substances against gamma photons and are able to enhance the structural and mechanical qualities.

Potential correlation of the hardness of CaO–Al2O3–SiO2 glasses with melting behavior

AbstractIt is proposed that the hardness of aluminosilicate glasses correlates with the melting temperature as predicted by the phase diagram. To evaluate this hypothesis, a broad range of CaO–Al2O3–SiO2 compositions was evaluated, verifying the glass formation region, and allowing for a systematic comparison of Vickers indentation hardness with melting temperature. Candidate glass forming compositions were restricted to the normal glass formation region (SiO2 &gt; CaO) and ranging from SiO2:CaO ratios of 1:1 to 9:1 and Al2O3:CaO ratios ranging from .2:1.0 to 1.3:1.0. Glass forming compositions were X‐ray amorphous. The correlation of hardness was nonlinear but showed reasonable correlation with the melting behavior, with the lowest hardness glass obtained for the eutectic composition. The maximum hardness was obtained in the narrow glass chemistry range of 1.0:1.0:1.5 to 1.0:1.2:1.5 (CaO:Al2O3:SiO2) in the vicinity of anorthite (CaO·Al2O3·2SiO2).

Scoping studies for low-temperature melting ZnO–Bi2O3–(B2O3, SiO2) binder glass

Low melting point glass systems were explored as candidates for binders of solid oxide nuclear wastes which include volatile elements such as radioactive iodine. The base glass systems considered were ZnO–Bi2O3–B2O3 and ZnO–Bi2O3–SiO2, with specific compositions selected for synthesis trials based on available phase diagrams and a desire to explore the whole glass-forming region. Ten compositions were synthesized by melt quenching. Promising candidate glass binders were selected based on the absence of crystallization and favorable thermal properties, including low glass transition temperature (Tg) combined with a high crystallization onset temperature. These thermal properties indicate stable glass forming which would lead to sintering behavior needed for glass binding. Compositional effects include: higher Bi2O3 content led to lower Tg values, high ZnO content generally led to crystallization on quench, and high SiO2 content resulted in requirements for excessively high melting temperature. 25ZnO–15Bi2O3–60B2O3 was down-selected for some detailed crystallization versus time and temperature studies.Graphical abstract

Investigation of ZnSe stability and dissolution behavior in As-S-Se chalcogenide glasses

Optical composite fibers based on active transition metal (TM)-doped semiconductor crystals are being investigated for use in mid-infrared (mid-IR) fiber laser systems. This study evaluates a candidate glass matrix system assessing its key physical properties and suitability for optical fiber drawing and examines the stability of TM-doped ZnSe crystals during processing. Results indicate that despite excellent refractive index matching between crystal and glass matrix and good fiber draw attributes, the stability of the crystalline dopant within the glass melt is severely impacted by melt conditions. The time and temperature dependence of this stability is mapped by X-ray diffraction (XRD) and second-harmonic generation (SHG) microscopy, illustrating how these tools can be used to track the phase stability and robustness throughout the melting process. Results show that in a range of sulfo-selenide based matrices, dissolution and re-precipitation of Zn-containing crystalline phases is a dominant mechanism.

Effects of pressure on structure and dynamics of metallic glass-forming liquid with miscibility gap

The metallic liquid with miscibility gap has been widely explored recently because of the increasing plastic deformation ability of phase-separated metallic glass. However, the poor glass-forming ability limits its application as the structural materials due to the positive mixing enthalpy of the two elements. Since high pressure is in favor of the formation of the glass, the effect of pressure on the structural and dynamical heterogeneity of phase-separated Cu50Ag50 liquid is investigated by molecular dynamics simulation in the pressure range of 0–16 GPa. The results clearly show that the pressure promotes the formation of metallic glass by increasing the number of fivefold symmetry cluster W and dynamical relaxation time; meanwhile, the liquid–liquid phase separation is also enhanced, and the homogenous atom pairs show stronger interaction than heterogeneous atom pairs with increasing pressure. The dynamical heterogeneity is related to the formation of fivefold symmetry clusters. The lower growing rate of W at higher pressure with decreasing temperature corresponds to the slow increase in dynamical heterogeneity. The pressured glass with miscibility gap may act as a candidate glass with improved plastic formation ability. The results explore the structural and dynamical heterogeneity of phase-separated liquid at atomic level.

Novel Ge–Ga–Te–CsBr glass system with ultrahigh resolvability of halide

CO2 molecule, one of the main molecules to create new life, should be probed accurately to detect the existence of life in exoplanets. The primary signature of CO2 molecule is approximately 15μm, and traditional S- and Se-based glass fibers are unsuitable. Thus, Te-based glass is the only ideal candidate glass for far-infrared detection. In this study, a new kind of Te-based chalcohalide glass system was discovered with relatively stable and large optical band gap. A traditional melt-quenching method was adopted to prepare a series of (Ge15Ga10Te75)100−x (CsBr)x chalcogenide glass samples. Experiment results indicate that the glass-forming ability and thermal properties of glass samples were improved when CsBr was added in the host of Ge–Ga–Te glass. Ge–Ga–Te glass could remarkably dissolve CsBr content as much as 85at.%, which is the highest halide content in all reports for Te-based chalcohalide glasses. Moreover, ΔT values of these glass samples were all above 100°C. The glass sample (Ge15Ga10Te75)65 (CsBr)35 with ΔT of 119°C was the largest, which was 7°C larger than that of Ge15Ga10Te75 host glass. The infrared transmission spectra of these glasses show that the far-infrared cut-off wavelengths of (Ge15Ga10Te75)100−x (CsBr)x chalcogenide glasses were all beyond 25μm. In conclusion, (Ge15Ga10Te75)100−x (CsBr)x chalcogenide glasses are potential materials for far-infrared optical application.

Indium–silver alloy nanocrystals glass with fluorescence: A model in borosilicate glasses

We demonstrated a model to realize the growth of indium–silver alloy nanocrystals in borosilicate glass by sol–gel method plus a controlled atmosphere. The presence of spherical indium–silver alloy nanoparticles with 5 nm average grain size and good dispersed form in borosilicate glass was confirmed by transmission electron microscopy imaging. Reduction of indium–silver ions to indium–silver alloy neutral nanocrystals was revealed through X-ray powder diffraction and X-ray photoelectron spectra (XPS). Remarkably, indium–silver alloy nanocrystals borosilicate glass exhibited fluorescence at around 423 nm which nominated it as the candidate glass for laser sources, nonlinear media and photonic applications.

Preparation and Optical Properties of AgIn Alloy Quantum Dots Doped Glass

Indium-silver alloy quantum dots doped sodium borosilicate(NBS) glass was prepared by Sol-Gel method with controlled atmosphere technology. The morphology and microstructure of AgIn alloy quantum dots in the glass were characterized by means of X-ray powder diffraction(XRD), X-ray photoelectron spectroscope(XPS), high- resolution transmission electron microscope(HRTEM) and electron diffraction(SAED). The fluorescent properties of the glass by fluorescence spectrometer were studied. The results showed that indium-silver alloy quantum dots with an average grain size of 5 nm were finely dispersed in the sodium borosilicate glass after heat-treated at 600℃. Indiumsilver alloy quantum dots in the glass exhibited a fluorescence peak at around 435 nm which nominated AgIn quantum dots doped NBS glass as the candidate glass for laser sources, nonlinear media and photonic applications.

Release of uranium from candidate wasteforms

AbstractLarge volumes of depleted natural and low-enriched uranium exist in the UK waste inventory. This work reports on initial investigations of the leaching performance of candidate glass and cement encapsulation matrices containing UO3 powder as well as that of uranium oxide powders. The surface areas of UO3 powder and the monolith samples of UO3 conditioned in the glass and cement matrices were very different making leaching comparisons difficult. The results showed that for both types of monolith conditioned samples a steady increase of uranium concentration in solution with time was generally not observed. The wt.% of uranium leached from UO3 conditioned in the lead borosilicate glass wasteform was approximately five orders of magnitude less than that leached from UO3 powder. Similarly, the quantities of uranium leached from UO3 conditioned in composite cement made with ordinary Portland cement, and from magnesium phosphate cement, were approximately four and three orders of magnitude, respectively, less than that leached from UO3 powder. The performance of a mixed oxide borosilicate glass wasteform was only slightly better than that of UO3 powder. This work shows that wasteforms based on encapsulation in lead borosilicate glass and cement matrices have the greatest potential for further development.

Comparative motif discovery combined with comparative transcriptomics yields accurate targetome and enhancer predictions

The identification of transcription factor binding sites, enhancers, and transcriptional target genes often relies on the integration of gene expression profiling and computational cis-regulatory sequence analysis. Methods for the prediction of cis-regulatory elements can take advantage of comparative genomics to increase signal-to-noise levels. However, gene expression data are usually derived from only one species. Here we investigate tissue-specific cross-species gene expression profiling by high-throughput sequencing, combined with cross-species motif discovery. First, we compared different methods for expression level quantification and cross-species integration using Tag-seq data. Using the optimal pipeline, we derived a set of genes with conserved expression during retinal determination across Drosophila melanogaster, Drosophila yakuba, and Drosophila virilis. These genes are enriched for binding sites of eye-related transcription factors including the zinc-finger Glass, a master regulator of photoreceptor differentiation. Validation of predicted Glass targets using RNA-seq in homozygous glass mutants confirms that the majority of our predictions are expressed downstream from Glass. Finally, we tested nine candidate enhancers by in vivo reporter assays and found eight of them to drive GFP in the eye disc, of which seven colocalize with the Glass protein, namely, scrt, chp, dpr10, CG6329, retn, Lim3, and dmrt99B. In conclusion, we show for the first time the combined use of cross-species expression profiling with cross-species motif discovery as a method to define a core developmental program, and we augment the candidate Glass targetome from a single known target gene, lozenge, to at least 62 conserved transcriptional targets.

The effects of glass weave on the low temperature flexure properties of composite laminates

A variety of glass fiber weaves are being considered for use in insulation materials in the International Thermonuclear Experimental Reactor central solenoid. In this study, three candidate glass weaves (1581, 7781, and 38050) were used with a Di-Glycidyl Ether of Bisphenol F (DGEBF) anhydride epoxy matrix to produce composite laminates of constant thickness. These laminates were compared at room temperature (295 K) and liquid nitrogen temperature (77 K) via three-point flexure tests. The material variables among these glass products were type of weave pattern (eight-harness satin versus plain), fiber surface treatment (epoxy compatible surface treatment versus no treatment), and cloth areal density. Based on the flexural elastic modulus and strength data at both 77 K and 295 K, the 7781/epoxy composites showed the highest values followed closely by 1581/epoxy. The 38050/epoxy performed quite poorly. The correlations of the laminate density with modulus and strength at both temperatures were almost linear. It was also found that the failure modes of samples having fibers with epoxy compatible surface treatment differed from those having no surface treatment.

A preliminary design methodology for fatigue life prediction of polymer composites for tidal turbine blades

Tidal turbine blades experience significant fatigue cycles during operation and it is expected that fatigue strength will be a major consideration in their design. Glass fibre reinforced polymers are a candidate low-cost material for this application. This article presents a methodology for preliminary fatigue design of glass fibre reinforced polymer tidal turbine blades. The methodology combines: (a) a hydrodynamic model for calculation of local distributions of fluid–blade forces; (b) a finite element structural model for prediction of blade strain distributions; (c) a fatigue damage accumulation model, which incorporates mean stress effects; and (d) uniaxial fatigue testing of two candidate glass fibre reinforced polymer materials (for illustrative purposes). The methodology is applied here for the preliminary design of a three-bladed tidal turbine concept, including tower shadow effects, and comparative assessment of pitch- and stall-regulated control with respect to fatigue performance.

Glass-containing composite cathode contact materials for solid oxide fuel cells

The feasibility of adding glass to conventional SOFC cathode contact materials in order to improve bonding to adjacent materials in the cell stack is assessed. A variety of candidate glass compositions are added to LSM and SSC. The important properties of the resulting composites, including conductivity, sintering behavior, coefficient of thermal expansion, and adhesion to LSCF and Mn1.5Co1.5O4-coated 441 stainless steel are used as screening parameters. Adhesion of LSM to LSCF improved from 3.9 to 5.3MPa upon addition of SCZ-8 glass. Adhesion of LSM to coated stainless steel improved from 1.8 to 3.9MPa upon addition of Schott GM31107 glass. The most promising cathode contact material/glass composites are coated onto Mn1.5Co1.5O4-coated 441 stainless steel substrates and subjected to area-specific resistance testing at 800°C. In all cases, area-specific resistance is found to be in the range 2.5–7.5mOhmcm2 and therefore acceptable. Indeed, addition of glass is found to improve bonding of the cathode contact material layer without sacrificing acceptable conductivity.

A New Faraday Rotation Measurement Method for the Study on Magneto Optical Property of PbO-Bi&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;-B&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; Glasses for Current Sensor Applications

MAGNETO-OPTICAL current transformers (MOCT) based on the Faraday Effect provide numerous advantages over the conventional transformers. However the commonly used materials in MOCT are crystals that are very expensive and temperature dependence thus will cause many problems for the output signal. Cost efficient diamagnetic PbO-Bi2O3-B2O3 (PBB) glass system is fabricated in this study, for the aim of obtaining a good candidate glass with high verdet constant and good temperature resistance to replace crystals. A home-made optical bench was setup, calibrated and used for measuring the verdet constant of the fabricated glasses. Glass with composition of 50%PbO-40%Bi2O3-10%B2O3 in mol showed high Verdet constant (0.1533 min/Gauss.cm) and good value of the figure of merit (0.02635 min/Gauss), which can be considered as the ideal candidate for MOCT applications.

Development of cesium containing glass for gamma irradiator

Cesium137 is considered an alternative candidate for the gamma source to be used in irradiators in place of CO60 because it is a long-lived gamma emitter and is a by-product of nuclear fission. Large quantities of Cs137 have been present in stored fission product high level waste and much larger quantities are potentially available from the operation of nuclear power reaction. Cs is isolated from the high level waste by Cs specific sorbant and converted in to glassy form to have safe use of highly radiotoxic isotope for irradiators in public domain. Several glass compositions containing Cs (Cs137-simulation) in the ternary system of Cesium Iron Phosphate (Cs2O-Fe2O3-P2O5), Cesium Borosilicate (Cs2O-B2O3-SiO2) and quaternary system of Cesium Sodium Borosilicate (Cs2O-Na2O-B2O3-SiO2), Cesium Lithium Borosilicate (Cs2O-Li2O-B2O3-SiO2) with minor additives like Al, Zn with varying concentration of Cs2O were prepared. Basic characteristics like fusion temperature, pouring temperature, homogeneity of the melt and its durability at room temperature in air (Hygroscopic nature) were noted for screening probable candidate glass formulation. The selected glass formulation was further characterized for its thermal properties like volatility loss at melting temperature, glass transition temperature and linear expansion coefficient by thermal analyzer and homogeneity by SEM/EDX and XRD.

Glass Development for Vitrification of Wet Intermediate Level Waste (WILW) from Decommissionning of the Hinkley Point ‘A’ Site

AbstractThe Immobilisation Science Laboratory, University of Sheffield, is working with Magnox South Ltd to develop a range of glass formulations that are suitable for vitrification of the Wet Intermediate Level Waste (WILW) envelope arising from decommissioning of the Hinkley Point ‘A’ (HPA) power station. Four waste mixtures or permutations are under consideration for volume reduction and immobilisation by vitrification. The inorganic fractions of several of the wastes are suitable for vitrification as they largely consist of SiO2, MgO, Fe2O3, Na2O, Al2O3 and CaO. However, difficulties may arise from the high organic and sulphurous contents of certain waste streams, particularly spent ion exchange (IEX) resins. IEX resin wastes may be the key factor in limiting waste loading, and possible thermal pre&amp;#61485;treatments of IEX resin to decrease C and S contents prior to vitrification have been investigated. Our results suggest that low&amp;#61485;temperature (90 °C) pre&amp;#61485;treatment is more favourable than high&amp;#61485;temperature (250, 450, 1000 °C) pre&amp;#61485;treatment. A thorough desktop study has provided initial candidate glass compositions which have been down&amp;#61485;selected on the basis of glass forming ability, melting temperature, viscosity, liquidus temperature, chemical durability and potential sulphate capacity. Early results for two of the candidate glass formulations indicate that formation of an amorphous product with at least 35 wt % (dry waste) loading is achievable for HPA IEX resin wastes.

Novel Refractory Alkaline Earth Silicate Sealing Glasses for Planar Solid Oxide Fuel Cells

“Refractory” Sr–Ca–Y–B–Si sealing glasses were developed for solid oxide fuel cells (SOFCs). The objective was to develop sealing glasses with appropriate thermal properties and minimal interfacial reactions with SOFC stack components, particularly ceramic electrolytes and metallic interconnects. The new glasses are described as refractory because their sealing temperatures are higher than traditional sealing temperatures for intermediate-temperature SOFC stacks . Six glasses were formulated and made by a conventional glass-making process. The glasses exhibited rapid crystallization kinetics during intermediate temperature heat-treatments. Their thermal properties were characterized in both the initial glassy state and the final crystallized state. Candidate glasses were also aged for at elevated temperatures. Thermal expansion measurements showed minimal change after aging. One candidate glass (YSO-1) was used to seal anode-supported electrolyte membranes to metallic interconnects at temperatures ranging from in air. Microstructure analysis revealed the presence of near the glass-ceramic/metal interface. The effect of composition on thermal properties and a possible reaction mechanism for the chromate formation are discussed.

Finite Element Analysis of Composite Worm Gears

Worm gears are commonly used in windshield wipers and power windows of automobiles. The goal of this work is to study several material problems, such as production bottlenecks and excessive scrap, resulting from the production of steel worm shafts. A possible solution is explored in this work by characterizing material properties of a promising candidate (glass reinforced acetal copolymer) that can replace steel in worm gears. Finite element analysis of the worm thread under static loading and constant temperature is performed in order to calculate the size of the new composite part. The results obtained in this work support the possibility of manufacturing composite worm shafts that could operate at elevated temperatures without sacrificing part performance, while reducing part weight leading to improved fuel economy, noise reduction, and manufacturing problems associated with the steel part. The finite element analysis shows that compared to a steel gear, the axial pitch of a composite worm gear must be increased by 250% in order for it to operate without failure for 10 years at a constant temperature of 23%C. This increase in the axial pitch would ramp up to 400%, if the composite worm gear is expected to operate for 10 years at a constant temperature of 100 C.

Attenuation of spectral interferences during laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) using an rf only collision and reaction cell

The reduction of spectral interferences in laser ablation inductively coupled plasma mass spectrometry was investigated using an rf only hexapole as a collision and reaction cell with H2 as the reaction gas and He as a buffer gas. Argon-based polyatomic ions (ArX+) were attenuated by between 1 and 6 orders of magnitude with H2 during laser ablation experiments whilst analyte transmission under the same parameters was maintained above 80%. The amount of ArX+ attenuation for a fixed volume of reactive H2 gas was proportional to the electronegativity of parent element X. Interferences were not significantly attenuated with He. However, a change from ‘dry’ to ‘wet’ conditions in the plasma led to reactions with water molecules in the cell giving an apparent reactivity for clean He buffer gas whilst reducing the efficiency of some reactions with H2. Improved accuracy and precision were demonstrated under optimised conditions for the analysis of trace elements in sulfide and carbonate standard reference materials as a result of background interference reduction. Multi-element analysis was possible with reactive gases in the reaction cell as demonstrated by the accurate analysis, to within 15% of the recommended values for most trace elements, of candidate glass reference materials using NIST SRM glasses for calibration.