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Structures of fluoride containing aluminosilicate low activity nuclear waste glasses: A molecular dynamics simulations study
Fluorine and other halides commonly exist in nuclear waste forms, and due to their volatile nature, halide retention poses an issue affecting waste loading during vitrification. The compositional effect on fluorine incorporation in aluminosilicate glasses is investigated through molecular dynamics simulations. Oxygen and fluorine coordination numbers around glass former and modifier cations, bond angle distributions, and medium range structure features such as Q n distributions, ring size distributions and neutron diffraction structure factors were calculated. It was found that fluorine has higher preference to bond to Ca 2+ than to Na + , both in the melt and the glass, and there is no Si-F bond formation in the glass but they do exist in the melt. Consequently, CaO for Na 2 O substitution can be an effective way to help fluorine retention without significantly changing the glass chemistry. Furthermore, these results thus provide insights on fluorine incorporation in the aluminosilicate nuclear waste glasses and the strategy on how to improve fluorine retention both in the glass and the melt.
Synthesis and characterization of binder-free Cr3C2 coatings on nickel-based alloys for molten fluoride salt corrosion resistance
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Measurement of europium (III)/europium (II) couple in fluoride molten salt for redox control in a molten salt reactor concept
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Electrolyte development for improved cycling performance of bismuth fluoride nanocomposite positive electrodes
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Effect of overcharge on Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 /Graphite lithium ion cells with poly(vinylidene fluoride) binder. I - Microstructural changes in the anode
Cells based on NMC/graphite, containing poly(vinylidene difluoride) (PVDF) binders in the positive and negative electrodes, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state-of-charge (SOC). At 250% SOC the cell vented. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of the anodes showed several state-of-overcharge-dependent trends. Starting at 120% SOC, dendrites appeared and increased in concentration as the SOC increased. Dendrite morphology appeared to be dependent on whether the active material was on the “dull” or “shiny” side of the copper collector. Significantly more delamination of the active material from the collector was seen on the “shiny” side of the collector particularly at 180 and 250% SOC. Transition metals were detected at 120% SOC and increased in concentration as the SOC increased. Finally, there was considerable spatial heterogeneity in the microstructures across each laminate with several regions displaying complex layered structures.
NaPb2(CO3)2Fx(OH)1-x(0 < x ≤ 1): A new member of alkali-lead carbonate fluoride system with large birefringence
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Poly(vinylidene fluoride)/ CaCu{sub 3}Ti{sub 4}O{sub 12} and La doped CaCu{sub 3}Ti{sub 4}O{sub 12} composites with improved dielectric and mechanical properties
Highlights: • High ϵ′ PVDF/CCTO and La doped CCTO composites prepared by Extrusion. • With addition of ceramic, there is substantial increase in the ϵ′ of matrix PVDF. • Composites exhibit double relaxation behavior. - Abstract: Melt extrusion process has been used to prepare high relative permittivity, ϵ' PVDF–CCTO and PVDF–LaCCTO composites. Phase composition has been studied using powder X-ray diffraction (XRD). Microstructural, dielectric and mechanical properties have also been studied. Young's modulus of PVDF increases with the ceramic reinforcement. Dielectric measurements are made in the frequency range 10{sup −2}–10{sup 6} Hz using two probe Novocontrol impedance analyser (ZG4) from room temp to 120 °C to study the dielectric relaxation. There is a substantial increase in ϵ' of the matrix PVDF on addition of LaCCTO.
A superior composite gel polymer electrolyte of Li7La3Zr2O12- poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for rechargeable solid-state lithium ion batteries
Highlights: • Solid electrolyte LLZO dispersed in PVDF-HFP matrix is studied. • Garnet inorganic fillers enhance the transport number of Li{sup +}. • Composite polymer electrolytes show superior electrochemical performance. • Coin cells (Li/PVDF-HFP: LLZO/LiFePO{sub 4}) show good cycling performance. - Abstract: High-quality solid electrolyte is essential for the growing need of lithium ion batteries. Herein, we report a novel organic-inorganic composite electrolyte based on Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} ceramic powder incorporated into PVDF-HFP through a simple combined method. At room temperature, the composite polymer electrolyte (CPE) possesses a good ionic transmission improvement of 3.71 × 10{sup −4} S cm{sup −1}. The CPE behaves a fine lithium ion transference number of 0.58 and an electrochemical window of up to 4.65 V. CPEs display meliorative electrochemical stability compared to pure PVDF-HFP electrolyte. The cathode presents an excellent initial discharge capacity of 163.1 mAh g{sup −1} at 0.2 C in Li/CPE/LiFePO{sub 4} cell. The cell with CPE displays much better capacity retention than that with pure PVDF-HFP electrolyte. The Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} modified PVDF-HFP is a promising electrolyte for lithium ion batteries.
Silica/poly(vinylidene fluoride) porous composite membranes for lithium-ion battery separators
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Thermodynamic modeling of CsF with LiF-NaF-KF for molten fluoride-fueled reactors
Gibbs energy models were developed to describe the thermochemical behavior of CsF in molten FLiNaK (46.5LiF-11.5NaF-42KF mol%), a proposed molten salt reactor (MSR) fuel solvent and coolant, as cesium is of concern due to its high radiotoxicity and volatility. Initially, it was necessary to obtain a more accurate Gibbs energy function for CsF which required fitting parameters to reported vapor pressures over condensed phase CsF. The pseudo-binary systems CsF-LiF, CsF-NaF and CsF-KF were then evaluated utilizing phase equilibria and enthalpy of mixing (Δ mix H) values, together with original differential scanning calorimetry (DSC) measurements performed for the CsF-LiF and CsF-KF systems. The CsF-LiF-NaF, CsF-LiF-KF and CsF-NaF-KF pseudo-ternary system representations were obtained by interpolation of the constituent pseudo-binary systems, with DSC measurements performed for the CsF-LiF-NaF system to corroborate the calculated liquidus temperature. Ultimately, the pseudo-ternary systems were interpolated to obtain Gibbs energy models for the pseudo-quaternary CsF-LiF-NaF-KF system, supported by DSC measurements at low CsF compositions (1–10 mol%), yielding computed equilibria and cesium-containing vapor pressures that compare favorably with reported values. In conclusion, the Molten Salt Thermal Properties Database – Thermochemical (MSTDB-TC) was subsequently expanded to include these Gibbs energy models allowing description of the thermochemical behavior of the CsF-LiF-NaF-KF system.
How do titanium and Ti6Al4V corrode in fluoridated medium as found in the oral cavity? An in vitro study
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Design and performance of a lead fluoride detector as a luminosity monitor
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A scaled experimental study of control blade insertion dynamics in Pebble-Bed Fluoride-Salt-Cooled High-Temperature Reactors
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Uncertainty analysis of Transportable Fluoride-salt-cooled High-temperature Reactor (TFHR) using coupled DAKOTA with RELAP-3D method
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