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12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O is Cotunnite-like structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Na2O sheet oriented in the (0, 0, 1) direction. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a trigonal non-coplanar geometry to three equivalent O2- atoms. All Na–O bond lengths are 2.37 Å. In the second Na1+ site, Na1+ is bonded to four equivalent O2- atoms to form a mixture of edge and corner-sharing NaO4 tetrahedra. There are three shorter (2.35 Å) and one longer (2.48 Å) Na–O bond lengths. O2- is bonded in a 7-coordinate geometry to seven Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Na1+ is bonded to four equivalent O2- atoms to form a mixture of edge and corner-sharing NaO4 tetrahedra. All Na–O bond lengths are 2.42 Å. O2- is bonded in a body-centered cubic geometry to eight equivalent Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O is Hydrophilite-like structured and crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Na1+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. There are one shorter (2.31 Å) and two longer (2.33 Å) Na–O bond lengths. O2- is bonded to six equivalent Na1+ atoms to form a mixture of edge and corner-sharing ONa6 octahedra. The corner-sharing octahedral tilt angles are 53°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O crystallizes in the trigonal P3 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.43–2.96 Å. In the second Na1+ site, Na1+ is bonded to four O2- atoms to form a mixture of distorted edge and corner-sharing NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.30–2.49 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to nine Na1+ atoms. In the second O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms. In the third O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O crystallizes in the trigonal P321 space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 square pyramids that share corners with ten equivalent NaO5 square pyramids, corners with six equivalent NaO4 tetrahedra, edges with six NaO5 square pyramids, and edges with six equivalent NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.55–2.62 Å. In the second Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with six NaO5 square pyramids, corners with ten equivalent NaO4 tetrahedra, edges with six NaO5 square pyramids, and edges with two equivalent NaO4 tetrahedra. There are two shorter (2.32 Å) and two longer (2.44 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 square pyramids that share corners with ten NaO5 square pyramids, corners with six equivalent NaO4 tetrahedra, edges with six NaO5 square pyramids, and edges with six equivalent NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.55–2.62 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms. In the second O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electroactive materials for rechargeable batteries

A secondary battery including a cathode having a primary cathode active material and an alkaline source material selected from the group consisting of Na2O, Na2O2, Na2S, NaF, NaCl, NaBr, Li2O, Li2O2, Li2S, LiF, LiCl, LiBr, Na2O, Na2O2, Na2S, NaF, NaCl, and a mixture of any two or more thereof; an anode having an anode active material; an electrolyte; and a separator.

Amine, Khalil↗
DOE OSTI2024

Glass-bonded ceramic waste forms for immobilization of radioiodine from caustic scrubber wastes

Glass-bonded sodalite composite waste forms have been developed for the immobilization of liquid radioactive wastes resulting from off-gas treatment during aqueous reprocessing of used nuclear fuel, with a particular focus on 129I. The proposed composite waste form is comprised of aluminosilicate ceramic phases containing volatile radionuclides bonded with a glassy matrix. In this work, a suite of ten candidate low-temperature glass binders (ZnO-Bi2O3-based glasses and a Na2O-B2O3-SiO2 glass) were examined. Six glasses were mixed with caustic scrubber waste simulant previously converted into a sodalite-rich material (to provide glass fractions of 10 and 20 wt.%), uniaxially pressed into pellets, and sintered at 350 °C or 550 °C for 8 h in air. Iodine retention after heat treatment was assessed by neutron activation analysis, showing retention of 67-100 % of expected iodine. The aqueous durabilities of the resulting materials were then determined, following the ASTM C1308 standard test, showing iodine releases of 1 to 23 g m-2 after 4 d. The cumulative iodine release for the best performing system (a zinc-bismuth-borate glass binder) was <1 g m-2, and its iodine retention from processing was 67 %. The iodine releases compared favorably with other waste forms. In parallel, this best-performing composition was also consolidated via hot isostatic pressing (HIP) in a stainless-steel canister at 550 °C for 2 h under 100 MPa pressure. The HIPed sample was produced at the ~20 g scale and showed improved densification and minimal reaction with the canister.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Thermal Properties of Sodium Borosilicate Glasses as a Function of Sulfur Content

SO3 additions, up to 3.0 wt%, were systematically investigated for effects on the physical properties of sodium borosilicate glass melted in air, with a sulfur-free composition of 50SiO2-10Al2O3-12B2O3-21Na2O-7CaO (wt%). Solubility measurements, using electron microscopy chemical analysis, determined the maximum loading to be ~1.5 wt% SO3. It was found that sulfur (here as sulfate) in this glass increased the glass transition temperature, thermal diffusivity, heat capacity, and thermal conductivity, and decreased the mass density. Structural analysis, performed with Raman spectroscopy, indicated that the borosilicate network polymerized with sulfur additions, presumably due to Na2O being required to charge compensate the ionic SO42- additions, thus becoming unavailable to form non-bridging oxygen in the silicate network. It is postulated that this increased crosslinking of the borosilicate backbone lead to a structure with higher dimensionality and average bond energy. This increased the mean free paths and vibration frequency of the phonons, which resulted in the observed increase in thermal properties.

Thermal properties, Borosilicate glass, Sulfur sol↗
DOE OSTI2021

Effects of Al:Si and (Al + Na):Si ratios on the properties of the international simple glass, part I: Physical properties

Understanding composition-structure-property relationships of high-alumina nuclear waste glasses are important for vitrification of nuclear waste at the Hanford Site. Two series of glasses were designed, one with varying Al:Si ratios and the other with (Al+Na):Si ratios based on the International Simple Glass (ISG, a simplified nuclear waste model glass), with Al2O3 ranging from 0 to 23 mol % (0 to 32 wt. %). The glasses were synthesized and characterized using electron probe microanalysis, X-ray photoelectron spectroscopy, small angle X-ray scattering, high temperature oxide melt solution calorimetry, and infrared spectroscopy. Glasses were crystal free, and the lowest Na2O and Al2O3 glass formed an immiscible glass phase. Evolution of various properties - glass transition temperature, percentage of 4-coordinated B, enthalpy of glass formation - and infrared spectroscopy results indicate that structural effects differ based on the glass series.

Nuclear Waste Glass↗
DOE OSTI2022

Conversion Kinetics and Ionic Conductivity in Na-β”-Alumina + YSZ (Naβ”AY) Sodium Solid Electrolyte via Vapor Phase Conversion Process

Sodium ion batteries have been receiving increasing attention and may see potential revival in the near future, particularly in large-scale grid energy storage coupling with wind and solar power generation, due to the abundant sodium resources, low cost, and sufficiently high energy density. Among the known sodium ion conductors, the Na-β”-alumina electrolyte remains highly attractive because of its high ionic conductivity. This study focuses on the vapor phase synthesis of a Na-β”-Alumina + YSZ (Naβ”AY) composite sodium electrolyte, which has higher mechanical strength and stability than conventional single phase β”-Alumina. The objectives are the measurement of conversion kinetics through a newly developed weight-gain based model and the determination of sodium ionic conductivity in the composite electrolyte. Starting samples contained ~70 vol% α-Alumina and ~30 vol% YSZ (3 mol% Y 2 O 3 stabilized Zirconia) with and without a thin alumina surface layer made by sintering in air at 1600 °C. The sintered samples were placed in a powder of Na-β”-alumina and heat-treated at 1250 °C for various periods. Sample dimensions and weight were measured as a function of heat treatment time. The conversion of α-Alumina in the α-Alumina + YSZ composite into Naβ”AY occurred by coupled diffusion of sodium ions through Na-β”-alumina and of oxygen ions through YSZ, effectively diffusing Na2O. From the analysis of the time dependence of sample mass and dimensions, the effective diffusion coefficient of Na 2 O through the sample, D eff , was estimated to be 1.74 x 10 -7 cm2 s -1 , and the effective interface transfer parameter, k eff , was estimated as 2.33 x 10 -6 cm s -1 . By depositing a thin alumina coating layer on top of the bulk composite, the chemical diffusion coefficient of oxygen through single phase Na-β”-alumina was estimated as 4.35 x 10 -10 cm 2 s -1 . An AC impedance measurement was performed on a fully converted Naβ”AY composite, and the conductivity of the composite electrolyte was 1.3 x 10 -1 S cm -1 at 300 °C and 1.6 x 10 -3 S cm -1 at 25 °C, indicating promising applications in solid state or molten salt batteries at low to intermediate temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effects of Al Substitution for Fe in Na₅FeSi₄O₁₂ (5.1.8) Glasses: Structure and Crystallization

In this study, the effects of substituting Al for Fe in 5Na2O∙(Al2O3)x∙(Fe2O3)1-x∙8SiO2 glass, x=0 to 1, and Na5AlxFe1-xSi4O12 (5.1.8) crystal, were investigated using thermal analysis, Fe K-edge X-ray absorption, X-ray diffraction, Raman spectroscopy, and Electron Probe Microanalysis. In both glass and crystallized glass, nearly all the Fe was tetrahedrally coordinated Fe3+, as expected from the high concentration of Na2O. The substitution of Al for Fe in the glasses caused the glass transition temperature to increase as polymerization increased, as evidenced by Raman, likely due to both field strength differences of Al vs Fe and a small amount of Fe2+ network modifier present with Fe. After heat treatment at 700 °C for 24 hours, the glasses had crystallized, forming Na2SiO3 and NaAlSiO4 in compositions with high Al concentrations and the 5.1.8 crystal in compositions with high Fe concentrations. Through electron microprobe, it was determined that <0.04 formula unit Al incorporated into the 5.1.8 crystal, i.e. Na5Fe0.96Al0.04Si4O12. The 5.1.8 crystal only formed when Fe concentration was higher than Al in the starting glass.

Antonio, Raine (ORCID:0009000634297975)↗
DOE OSTI2020

Coated U3Si2 pellets with enhanced water and steam oxidation resistance

A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises coating the fissile material, such as a pellet of U3Si2 and/or the grain boundaries, to a desired thickness with a suitable coating material, such as atomic layer deposition or a thermal spray process. The coating material may be any non-reactive material with a solubility at least as low as that of UO2. Exemplary coating materials include ZrSiO4, FeCrAl, Cr, Zr, Al—Cr, CrAl, ZrO2, CeO2, TiO2, SiO2, UO2, ZrB2, Na2O—B2O3—SiO2—Al2O3 glass, Al2O3, Cr2O3, carbon, and SiC, and combinations thereof. The water resistant layer may be overlayed with a burnable absorber layer, such as ZrB2 or B2O3—SiO2 glass.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗