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At least 703 records · Page 39

Thin films printed with chalcogenide glass inks

A device formation method may include printing a chalcogenide glass ink onto a surface to form a chalcogenide glass layer, where the chalcogenide glass ink comprises chalcogenide glass and a fluid medium. The method may further include sintering the chalcogenide glass layer at a first temperature for a first duration. The method may also include annealing the chalcogenide glass layer at a second temperature for a second duration. A device may include a substrate and a printed chalcogenide glass layer on the substrate, where the printed chalcogenide glass layer includes annealed chalcogenide glass, and where the printed chalcogenide glass layer is free from cracks.

Mitkova, Maria↗

PREPARATION OF CLAY-COATED GLASS SURFACES FOR MICROFLUIDICS-BASED STUDY ON CLAY-FLUID INTERACTIONS

Unique characteristics of clay, even though make any clay abundant shales a good source of adsorbed gas, make them equally difficult to produce. The clay-water interaction can cause significant swelling and fines migration in the shale formation, both of which can significantly impair the overall hydrocarbon recovery from shale. Geomaterial micromodels, developed by functionalizing traditional glass or PDMS surface with geomaterials (e.g., calcite, quartz, clay) can represent the physico-chemical properties of the natural porous media and have been used during the last few years to understand and evaluate the solid-fluid physicochemical interactions. This study focuses on developing a clay-coated geomaterial surface and investigates the effect of base fluid's salinity on clay adsorption to the glass surface. Glass capillary tubes and straight channel borosilicate glass micromodels are coated with Illite clay minerals to represent the pore-scale clay chemistry of Caney Shale, a Mississippian unconventional play in Southern Oklahoma, USA. 10 wt.% of Illite clay slurries made with brines of four different salinities are used to coat the glass-capillary tubes to understand the effect of salinity in clay adsorption on the glass surface and overall coating quality. To achieve a stable coating and evaluate the impact of heat treatment on coating's stability, straight channel glass flow cells coated with Illite clay are heat-treated at low (25 °C) and high temperature (125 °C). Dynamic flooding tests were carried out with brines on the coated surface to evaluate the stability of the coating. The experiments' outcome indicated a strong relationship between the brine's salinity and the adsorption of clay particles on the glass surface. An increase in brine concentration resulted in improved adsorption of clay particles on the glass surface. Experiments involving heat treating the glass surface following the coating demonstrated significant improvement in the stability of the coating.

02 PETROLEUM↗

Glass formation during combinatorial sputtering in binary alloys

Glass formation is a complex phenomenon influenced by thermodynamic and kinetic aspects, which are often controlled by extrinsic contributions. While bulk metallic glasses are typically multicomponent alloys, binary alloys offer a simplified approach to studying glass formation. In this study, we fabricated 57 binary alloy systems through combinatorial sputtering, where each alloy system is represented in 66 different alloys. We developed an automated analysis to determine structure and composition using X-ray diffraction and energy-dispersive X-ray spectroscopy for over 3700 alloys. We found that ∼17 % of the alloys form glasses under the estimated cooling rate during sputtering of ∼10 8 K/s. Data analysis revealed that commonly used factors like atomic size ratio and heat of mixing are ineffective in predicting glass formation. However, the crystal structure mismatch of the alloys’ elements emerged as the strongest indicator of glass formation under sputtering conditions of binary alloys. Here, the differences in glass formation under slow cooling rates used for bulk glass formation and the here observed glass formation under rapid cooling rates are discussed.

Binary alloys↗

Structural features of sodium silicate glasses from reactive force field-based molecular dynamics simulations

Atomistic computer simulations can offer insights into silicate glass-environment interactions with the recent development of reactive potentials. Yet, the accuracy of generated glass structures with these potential was usually not fully examined. In this paper, the capability of the reactive force field (ReaxFF) to describe the short and medium range structure features of sodium silicate glasses in molecular dynamics simulations is investigated by comparing a widely used partial charge pairwise potential and available experimental data. Glass structure information such as pair distribution function (PDF), coordination number, Qn species, neutron broadened structure factor, and X-ray broadened structure factor of the glass structures from ReaxFF simulations were calculated and compared to evaluate the generated glass structure. Advantages and limitations of the potentials and glass forming procedures, as well as areas of further improvement, were discussed. The results show that the recently refined ReaxFF parameters through the proposed procedure enable the simulations of sodium silicate glass structures with minimal defects, which paves the way to investigate water-glass interaction mechanisms with the reactive enabled potentials.

36 MATERIALS SCIENCE↗

WTP Waste Feed Qualification: Glass Fabrication Unit Operation Testing Report

The waste feed qualification program is being developed to protect the Hanford Tank Waste Treatment and Immobilization Plant (WTP) design, safety basis, and technical basis by assuring waste acceptance requirements are met for each staged waste feed campaign prior to transfer from the Tank Operations Contractor to the feed receipt vessels inside the Pretreatment Facility. The Waste Feed Qualification Program Plan describes the three components of waste feed qualification: 1. Demonstrate compliance with the waste acceptance criteria 2. Determine waste processability 3. Test unit operations at laboratory scale. The glass fabrication unit operation is the final step in the process demonstration portion of the waste feed qualification process. This unit operation generally consists of combining each of the waste feed streams (high-level waste (HLW) and low-activity waste (LAW)) with Glass Forming Chemicals (GFCs), fabricating glass coupons, performing chemical composition analysis before and after glass fabrication, measuring hydrogen generation rate either before or after glass former addition, measuring rheological properties before and after glass former addition, and visual observation of the resulting glass coupons. Critical aspects of this unit operation are mixing and sampling of the waste and melter feeds to ensure representative samples are obtained as well as ensuring the fabrication process for the glass coupon is adequate. Testing was performed using a range of simulants (LAW and HLW simulants), and these simulants were mixed with high and low bounding amounts of GFCs to evaluate the mixing, sampling, and glass preparation steps in shielded cells using laboratory techniques. The tests were performed with off-the-shelf equipment at the Savannah River National Laboratory (SRNL) that is similar to equipment used in the SRNL work during qualification of waste feed for the Defense Waste Processing Facility (DWPF) and other waste treatment facilities at the Savannah River Site. It is not expected that the exact equipment used during this testing will be used during the waste feed qualification testing for WTP, but functionally similar equipment will be used such that the techniques demonstrated would be applicable. For example, the mixing apparatus could use any suitable mixer capable of being remoted and achieving similar mixing speeds to those tested.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

GLASSES CONTAINING IRON (II III) OXIDES FOR IMMOBILIZATION OF RADIOACTIVE TECHNETIUM

Technetium-99 (Tc-99) has posed serious environmental threats as US Department of Energy's high-level waste. This work reports the vitrification of Re, as surrogate for Tc-99, by iron-borosilicate and iron-phosphate glasses, respectively. Iron-phosphate glasses can dissolve Re as high as {approx} 1.2 wt. %, which can become candidate waste forms for Tc-99 disposal, while borosilicate glasses can retain less than 0.1 wt. % of Re due to high melting temperature and long melting duration. Vitrification of Re as Tc-99's mimic was investigated using iron-borosilicate and iron-phosphate glasses. The retention of Re in borosilicate glasses was less than 0.1 wt. % and more than 99 wt. % of Re were volatilized due to high melting temperature and long melting duration. Because the retention of Re in iron-phosphate glasses is as high as 1.2 wt. % and the volatilization is reduced down to {approx}50 wt. %, iron-phosphate glasses can be one of the glass waste form candidates for Tc (or Re) disposal. The investigations of chemical durability and leaching test of iron-phosphate glasses containing Re are now underway to test the performance of the waste form.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Solid-State NMR Examination of Alteration Layers on a Nuclear Waste Glasses

Solid-state NMR is a powerful tool for probing the role and significance of alteration layers in determining the kinetics for the corrosion of nuclear waste glass. NMR methods are used to probe the chemical structure of the alteration layers to elucidate information about their chemical complexity, leading to increased insight into the mechanism of altered layer formation. Two glass compositions were examined in this study: a glass preliminarily designed for nuclear waste immobilization (called AFCI) and a simplified version of this AFCI glass (which we call SA1R). Powdered glasses with controlled and known particles sizes were corroded at 90 °C for periods of one and five months with a surface-area to solution-volume ratio of 100,000 m-1. 1H-29Si CP-CPMG MAS NMR, 1H-27Al CP-MAS NMR, 1H-11B CP-MAS NMR, and 1H-23Na CP-MAS NMR experiments provide isolated structural information about the alteration layers, which differ in structure from that of the pristine glass. Both glasses studied here develop alteration layers composed primarily of [IV]Si species. Aluminum is also retained in the alteration layers, perhaps facilitated by the observed increase in coordination from [IV]Al to [VI]Al, which correlates with a loss of charge balancing cations. 1H-11B CP-MAS NMR observations indicated a retention of boron in hydrated glass layers, which has not been characterized by previous work. For the AFCI glass, secondary phase formation begins during the corrosion times considered here, and these neophases are detected within the alteration layers. We identify precursor phases as crystalline sodium metasilicates. An important finding is that layer thickness depends on the length of the initial alteration stages and varies only with respect to silicon species during the residual rate regime.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Arrhenian to non-Arrhenian crossover in glass melt viscosity

The activation energy for glass melt viscosity is a function of temperature, i.e., non-Arrhenian, within a middle range of viscosity values (typically, between 10 2 and 10 10 Pa s) and constant, i.e., Arrhenian, outside this range. At the low-viscosity end, the Arrhenian to non-Arrhenian transition (termed the crossover) falls within the glass processing range: glass melting and fining occur within the Arrhenian range while glass forming occurs within the non-Arrhenian range. By the Adam-Gibbs equation, the configuration entropy is nearly constant at high temperatures (low viscosities), where the glass melt turns into a simple liquid, and decreases with decreasing temperature (increasing viscosity) as the glass is increasingly polymerized. In the present study, the power-law function and hyperbolic tangent function are used to express the configuration entropy as a function of temperature. The viscosity crossover is defined as the point at which onset of structural grouping is causing the configuration entropy to deviate from its high-temperature value. In conclusion, it appears that the limited range of the configuration entropy of the fully depolymerized melt imposes a restriction on the crossover viscosity; for well-defined glass families, such as float glasses or nuclear waste glasses, the crossover point can be defined using a fixed, i.e., composition-independent, viscosity value.

36 MATERIALS SCIENCE↗

Tellurite glass as a waste form for a simulated mixed chloride waste stream: Candidate materials selection and initial testing

Tellurite glasses have been researched widely for the last 60 years since they were first introduced by Stanworth. These glasses have been primarily used in research applications as glass host materials for lasers and as non-linear optical materials, though many other uses exist in the literature. Tellurite glasses have long since been used as hosts for various, and even sometimes mixed, halogens (i.e., multiple chlorides or even chlorides and iodides). Thus, it was reasonable to expect that these types of glasses could be used as a waste form to immobilize a combination of mixed chlorides present in the electrochemical separations process involved with fuel separations and processing from nuclear reactors. Many of the properties related to waste forms (e.g., chemical durability, maximum chloride loading) for these materials are unknown and thus, in this study, several different types of tellurite glasses were made and their properties studied to determine if such a candidate waste form could be fabricated with these glasses. One of the formulations studied was a lead tellurite glass, which had a low sodium release and is on-par with high-level waste silicate glass waste forms.

electrochemical↗

H + diffusion and electrochemical stability of Li 1+x+y Al x Ti 2-x SiyP 3-y O 12 glass in aqueous Li/air battery electrolytes

It is well known that LATP (Li 1+x+y Al x Ti 2-x SiyP 3-y O 12 ) glass is a good lithium ion conductor. However, the interaction between LATP glass and H+ ions (including its diffusion and surface adsorption) needs to be well understood before the long-term application of LATP glass in an aqueous electrolyte based Li-air batteries where H+ always present. In this work, we investigate the H+ ion diffusion properties in LATP glass and their surface interactions using both experimental and modeling approaches. Our analysis indicates that the apparent H+ related current observed in the initial cyclic voltammetry scan should be attributed to the adsorption of H+ ions on the LATP glass rather than the bulk diffusion of H+ ions in the glass. Furthermore, the density functional theory calculations indicate that the H+ ion diffusion energy barrier (3.21 eV) is much higher than that of Li+ ion (0.79 eV) and Na+ ion (0.79 eV) in NASICON type LiTi 2 (PO 4 ) 3 material. As a result, the H+ ion conductivity in LATP glass is negligible at room temperature. However, significant surface corrosion was found after the LATP glass was soaked in strong alkaline electrolyte for extended time. Therefore, appropriate electrolytes have to be developed to prevent the corrosion of LATP glass before its practical application for Li-air batteries using aqueous electrolyte.

25 ENERGY STORAGE↗

Influence of NaX (X=I or Cl) additions on GeS{sub 2}–Ga{sub 2}S{sub 3} based glasses

Chalcogenide glasses in the pseudo-ternary system NaX–GeS{sub 2}–Ga{sub 2}S{sub 3} (X=Cl or I) were synthesized. Different series were investigated in order to highlight the influence of the sodium halide addition on two different host glasses (GeS{sub 2}){sub 80}(Ga{sub 2}S{sub 3}){sub 20} and (GeS{sub 2}){sub 72}(Ga{sub 2}S{sub 3}){sub 28}. Macroscopic properties including density and characteristic temperatures, such as glass transition temperatures T{sub g} and crystallization temperature T{sub x}, were determined for a maximum molar content of NaX equal to 15%. The evolution of the optical band-gap and the chemical stability following the composition were also studied. Conductivity measurements were also performed and compared to other Li-based GeS{sub 2}–Ga{sub 2}S{sub 3} glasses. The results were discussed taking into account the cation and anion nature and also the glass packing density. - Graphical abstract: Characterizations of NaX–GeS{sub 2}–Ga{sub 2}S{sub 3} chalcogenide glasses (X=Cl or I). - Highlights: • Synthesis and characterization of NaX–GeS{sub 2}–Ga{sub 2}S{sub 3} chalcogenide glasses (X=Cl or I). • We compare results with analoguous LiX-bearing glasses. • Correlation between electrical conductivity and glass packing density.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

New chalcogenide glasses in the CdTe-AgI-As{sub 2}Te{sub 3} system

Highlights: Black-Right-Pointing-Pointer Determination of the glass-forming region in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system. Black-Right-Pointing-Pointer Characterization of macroscopic properties of the new CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Characterization of the total conductivity of CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Comparison between the selenide and telluride equivalent systems. -- Abstract: Chalcogenide glasses in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system were synthesized and the glass-forming range was determined. The maximum content of CdTe in this glass system was found to be equal to 15 mol.%. The macroscopic characterizations of samples have consisted in Differential Scanning Calorimetry, density, and X-ray diffraction measurements. The cadmium telluride addition does not generate any significant change in the glass transition temperature but the resistance of binary AgI-As{sub 2}Te{sub 3} glasses towards crystallisation is estimated to be decreasing on the base of {Delta}T = T{sub x} - T{sub g} parameter. The total electrical conductivity {sigma} was measured by complex impedance spectroscopy. First, the CdTe additions in the (AgI){sub 0.5}(As{sub 2}Te{sub 3}){sub 0.5} host glass, (CdTe){sub x}(AgI){sub 0.5-x/2}(As{sub 2}Te{sub 3}){sub 0.5-x/2} lead to a conductivity decrease at x {<=} 0.05. Then, the behaviour is reversed at 0.05 {<=} x {<=} 0.15. The obtained results are discussed by comparison with the equivalent selenide system.

36 MATERIALS SCIENCE↗

Structural, thermal, optical properties and simulation of white light of titanium-tungstate-tellurite glasses doped with dysprosium

Graphical abstract: CIE coordinate diagram of different concentrations of the Dy{sup 3+}-doped TTWD glasses with coordinates in the white light region. - Highlights: • Radiative lifetime of {sup 4}F{sub 9/2} level of Dy{sup 3+} ions is longer in the tellurite glass. • Quantum efficiency is found to be high. • These glasses are suitable materials for generating white light. - Abstract: Structural, thermal, optical properties and simulation of white light of Dy{sup 3+}-doped tellurite glasses of composition TTWD: (75 − x)TeO{sub 2} − 10TiO{sub 2} − 15WO{sub 3} − xDy{sub 2}O{sub 3} (x = 0, 0.1, 0.5, 1.0 and 2.0 mol%) were investigated. Raman spectra revealed that the glass contains TeO{sub 4}, TeO{sub 3}, WO{sub 4} and WO{sub 6} units. Differential scanning calorimetry (DSC) measurements were carried out to measure the glass transition temperature of all the glasses. From the optical absorption spectra, luminescence spectra and using the Judd–Ofelt (JO) analysis, we estimated the radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes. The decay curves at lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (≥0.5 mol%) due to energy transfer processes. The effective lifetime for the {sup 4}F{sub 9/2} level decreases with increase in Dy{sub 2}O{sub 3} concentration for the glasses under investigation. The non-exponential decay curves could fit well to the Inokuti–Hirayama (IH) model with S = 6, indicating that the nature of interaction responsible for energy transfer is of dipole–dipole type. Simulation of white light is examined with varying concentration and the results indicate that these glasses are suitable for white light emitting diode applications.

36 MATERIALS SCIENCE↗

∼2 μm fluorescence radiative dynamics and energy transfer between Er{sup 3+} and Tm{sup 3+} ions in silicate glass

Graphical abstract: - Highlights: • A Er{sup 3+}/Tm{sup 3+} co-doped silicate glass with good thermal stability (k{sub gl} = 0.402 for STE glass) is prepared. • Efficient ∼2 μm emission is observed under 808 nm and 980 nm laser excitation. • The glass structure and spectroscopic properties are confirmed by optical absorption, IR transmission, Raman and fluorescence studies. • The content of OH groups deceases efficiently after fluorine ions are introduced. • The energy transfer coefficient from Er{sup 3+} to Tm{sup 3+} in STFE glass is 13.39 × 10{sup −40} cm{sup 6}/s. - Abstract: A Er{sup 3+}/Tm{sup 3+} co-doped silicate glass with good thermal stability is prepared by melt-quenching method. An efficient emission of ∼2 μm is observed under different selective laser excitations. The optical absorption and transmission spectra, Raman spectra, and emission spectra are tested to characterize ∼2 μm emission properties of Er{sup 3+}/Tm{sup 3+} co-doped silicate glasses and a reasonable energy transfer mechanism of ∼2 μm emission between Er{sup 3+} and Tm{sup 3+} ions is proposed. Based on the optical absorption spectra, the Judd–Ofelt parameters and radiative properties were calculated. Intense ∼2 μm emission is obtained from Er{sup 3+}/Tm{sup 3+} co-doped silicate glasses due to the efficient energy transfer from Er{sup 3+} to Tm{sup 3+} ions. The energy transfer coefficient from Er{sup 3+} to Tm{sup 3+} ions can reach as high as 13.39 × 10{sup −40} cm{sup 6}/s. In addition, the population of the OH groups is decreased and the ∼2 μm emission is effectively enhanced with fluoride introduction. The emission property, together with good thermal property, indicates that Er{sup 3+}/Tm{sup 3+} co-doped silicate glass is a potential kind of laser glass for efficient ∼2 μm laser.

36 MATERIALS SCIENCE↗

Structural, thermal and spectroscopic properties of highly Er3+-doped novel oxyfluoride glasses for photonic application

Graphical abstract: - Highlights: • Er{sup 3+}-doped novel oxyfluoride glasses have been prepared by melt quenching technique. • Structural, thermal and spectroscopic properties have been carried out. • SALSFEr glasses exhibit intense green and weak red emissions at 365 nm excitation. • Major laser transition for Er{sup 3+} ion in SALSFEr glasses is {sup 4}I{sub 13/2} → {sup 4}I{sub 15/2} (1.53 μm). • These results suggest the possibility of using SALSFEr glasses as photonic devices. - Abstract: The Er{sup 3+}-doped novel oxyfluoride glasses of composition (43 − x)SiO{sub 2}–10Al{sub 2}O{sub 3}–24LiF–23SrF{sub 2}–xEr{sub 2}O{sub 3}, where x = 1.0, 2.0, 4.0 and 6.0 mol%, have been prepared by conventional melt quenching technique and are characterized through X-ray diffraction (XRD), differential thermal analysis (DTA), Raman, Fourier transform infrared (FT-IR) analysis, optical absorption spectra, visible (vis) and near-infrared (NIR) emission spectra measurements. Judd–Ofelt (JO) intensity parameters (Ω{sub λ}, λ = 2, 4 and 6) have been derived from the absorption spectrum of 1.0 mol% Er{sub 2}O{sub 3} doped glass and are in turn used to calculate radiative properties for the important luminescent levels of Er{sup 3+} ions. The studied glasses show intense green and weak red visible emissions under 365 nm excitation. The decrease in visible emission intensities with concentration of Er{sup 3+} ions has been explained due to energy transfer processes between Er{sup 3+} ions. Upon excitation at 980 nm laser diode, an intense 1.53 μm NIR emission has been observed with the maximum full width at half maximum (FWHM) for Er{sup 3+}-doped oxyfluoride glasses. The higher Er{sup 3+} ion doping capability and relatively high gain and broad emission at 1.5 μm are the most notable features of these glasses to realize efficient short-length optical amplifiers.

36 MATERIALS SCIENCE↗

Photocatalytic study on SrBi2B2O7 (SrO-Bi2O3-B2O3) transparent glass ceramics

Highlights: • SrO-Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} transparent glass ceramic was fabricated via melt-quenching. • XRD and SEM revealed nucleation of SrBi{sub 2}B{sub 2}O{sub 7} nanocrystals over glass surface. • SrBi{sub 2}B{sub 2}O{sub 7} nanocrystals were found responsible for photocatalytic activity. • Rz ink test was performed to test self-cleaning ability of glass. • Digital photographic method was opted to view self-cleaning of glass. - Abstract: SrO-Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} transparent glass ceramic was fabricated via conventional melt-quenching technique. Structural analysis like X-ray diffraction, Raman and Fourier transform infrared spectroscopies were performed to confirm SBBO glass ceramic formation. As-quenched glass samples exhibited X-ray diffraction peaks corresponding to SrBi{sub 2}B{sub 2}O{sub 7} which were further confirmed through Field Emission Scanning Electron Microscope. UV–vis transmission spectra revealed 60%–80% transparency in 500–800 nm spectral range. Absorption study revealed direct bandgap of 2.58 eV. Resazurin (Rz) ink was used as an indicator to monitor photocatalytic activity for self-cleaning purposes. Digital photographic method was performed to examine photoreduction of Rz ink. Further, the pseudo-first order kinetics was istimated for Methylene blue (MB) degradation. Nucleation of nanoparticles of SrBi{sub 2}B{sub 2}O{sub 7} over glass surface were found responsible for photocatalytic activity. Contact angle with water droplet for SBBO glass ceramic was 63.43°. Reduced Young’s modulus (E{sub r}) and Vickers hardness (H{sub v}) were found 59.9 GPa and 5.01 GPa, respectively.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Enhanced resonant nonlinear absorption and optical limiting in Er3+ ions doped multicomponent tellurite glasses

Highlights: • Nonlinear optical properties of TPBKZFEr glasses investigated by Z-scan technique. • Optical limiting property of the TPBKZFEr glasses is studied for the first time. • Nonlinearity of the prepared glasses found to be enhanced with Er{sup 3+} concentration. • The mechanism behind the nonlinear properties is successfully explained. • It is evident that these glasses can be developed as tunable optical limiters. - Abstract: Nonlinear optical properties of multicomponent tellurite glasses doped with Er{sup 3+} ions were investigated by open aperture Z-scan measurements. Compositional and linear optical properties of the glasses were examined by the energy dispersive X-ray spectrum and UV–vis–NIR absorption spectrum analysis respectively. The mechanism behind the optical nonlinearity and optical limiting efficiency was successfully explained by evaluating the physical properties such as density, refractive index and polarizability of the glasses. The nonlinear properties critically depend on the polarizability, which is found to increase with the addition of Er{sup 3+} ions by the creation of non-bridging oxygen ions. By the systematic addition of Er{sup 3+} ions, we have dictated the physical properties and thus tuned the optical limiting efficiency of the glasses. This makes the Er{sup 3+}-doped multicomponent tellurite glasses flexible tunable optical limiters for potential device applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Compositional Models of Glass/Melt Properties and their Use for Glass Formulation

Nuclear waste glasses must simultaneously meet a number of criteria related to their processability, product quality, and cost factors. The properties that must be controlled in glass formulation and waste vitrification plant operation tend to vary smoothly with composition allowing for glass property-composition models to be developed and used. Models have been fit to the key glass properties. The properties are transformed so that simple functions of composition (e.g., linear, polynomial, or component ratios) can be used as model forms. The model forms are fit to experimental data designed statistically to efficiently cover the composition space of interest. Examples of these models are found in literature. The glass property-composition models, their uncertainty definitions, property constraints, and optimality criteria are combined to formulate optimal glass compositions, control composition in vitrification plants, and to qualify waste glasses for disposal. An overview of current glass property-composition modeling techniques is summarized in this paper along with an example of how those models are applied to glass formulation and product qualification at the planned Hanford high-level waste vitrification plant.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗