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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

The sodium channel Na X : Possible player in excitation–contraction coupling

Abstract The sodium channel Na X (encoded by the SCN7A gene) was originally identified in the heart and skeletal muscle and is structurally similar to the other voltage‐gated sodium channels but does not appear to be voltage gated. Although Na X is expressed at high levels in cardiac and skeletal muscle, little information exists on the function of Na X in these tissues. Transcriptional profiling of ion channels in the heart in a subset of patients with Brugada syndrome revealed an inverse relationship between the expression of Na X and Na V 1.5 suggesting that, in cardiac myocytes, the expression of these channels may be linked. We propose that Na X plays a role in excitation–contraction coupling based on our experimental observations. Here we show that in cardiac myocytes, Na X is expressed in a striated pattern on the sarcolemma in regions corresponding to the sarcomeric M‐line. Knocking down Na X expression decreased Na V 1.5 mRNA and protein and reduced the inward sodium current ( I Na+ ) following cell depolarization. When the expression of Na V 1.5 was knocked down, ~85% of the I Na+ was reduced consistent with the observations that Na V 1.5 is the main voltage‐gated sodium channel in cardiac muscle and that Na X likely does not directly participate in mediating the I Na+ following depolarization. Silencing Na V 1.5 expression led to significant upregulation of Na X mRNA. Similar to Na V 1.5, Na X protein levels were rapidly downregulated when the intracellular [Ca 2+ ] was increased either by CaCl 2 or caffeine. These data suggest that a relationship exists between Na X and Na V 1.5 and that Na X may play a role in excitation–contraction coupling.

Bogdanovic, Elena↗
DOE OSTI2021

Synthesis of a planar, multicomponent catalytic surface of Na 2 CO 3 /MnO

Here, O 2 adsorption on MnO(100) precovered with sodium (Na) multilayers was investigated by X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Deposition of Na multilayers leads to a first monolayer of oxidic Na followed by metallic Na island growth. XPS results for the oxidation of the metallic Na islands indicate an incomplete oxidation of Na at 125 K. Oxidation at 350 K completely oxidizes the metallic islands producing a mixture of Na 2 O and Na 2 O 2 . Thermal evolution of the oxidation products was examined. After oxidation at 350 K and flashing to 750 K, Na 2 O and Na 2 O 2 are the primary oxides on MnO(100). After flashing to 850 K, a solid state reaction of Na 2 O 2 /Na 2 O and the MnO(100) substrate forms a NaMnO 2 -like surface compound which decomposes above 850 K. Oxygen exchange between CO 2 and Na oxides is observed. The strong interaction between CO 2 and Na oxide islands forms Na 2 CO 3 on MnO(100). Heating the Na 2 CO 3 covered MnO(100) surface to 600 K for 10 min drives oxidic Na in the first monolayer into the MnO subsurface, and produces a surface exposing islands of Na 2 CO 3 on MnO(100).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Na(BH)5 by Materials Project

Na2(BH)9BH crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of four boranediylradical molecules and two Na2(BH)9 ribbons oriented in the (1, 0, 0) direction. In each Na2(BH)9 ribbon, there are two inequivalent Na sites. In the first Na site, Na is bonded in a 3-coordinate geometry to six H atoms. There are a spread of Na–H bond distances ranging from 2.09–2.61 Å. In the second Na site, Na is bonded in a 7-coordinate geometry to seven H atoms. There are a spread of Na–H bond distances ranging from 2.40–2.70 Å. There are nine inequivalent B sites. In the first B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the second B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the third B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the fourth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the fifth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.19 Å. In the sixth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the seventh B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the eighth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the ninth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. There are nine inequivalent H sites. In the first H site, H is bonded in a 3-coordinate geometry to two Na and one B atom. In the second H site, H is bonded in a distorted single-bond geometry to two equivalent Na and one B atom. In the third H site, H is bonded in a 2-coordinate geometry to two Na and one B atom. In the fourth H site, H is bonded in a linear geometry to one Na and one B atom. In the fifth H site, H is bonded in a linear geometry to one Na and one B atom. In the sixth H site, H is bonded in a distorted water-like geometry to one Na and one B atom. In the seventh H site, H is bonded in a distorted single-bond geometry to two Na and one B atom. In the eighth H site, H is bonded in a single-bond geometry to one Na and one B atom. In the ninth H site, H is bonded in a distorted single-bond geometry to one Na and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Thermodynamic modeling of calcium carbonate scale precipitation: aqueous Na + -Ca 2+ -Cl – -HCO 3 – -CO 3 2– -CO 2 system

To allow for accurate calculations of calcium carbonate scaling in highly saline produced waters, we present a comprehensive thermodynamic model based on the electrolyte nonrandom two-liquid (eNRTL) activity coefficient equation for the aqueous Na ⁺ -Ca ²⁺ -Cl – -HCO 3 – -CO 3 ²– -CO 2 system. The eNRTL binary interaction parameters for the H 2 O:(Na ⁺ -CO 3 2– ) pair, the H 2 O:(Na ⁺ -HCO 3 – ) pair, the (Na⁺-Cl–):(Na ⁺ -CO 3 2– ) pair, and the (Na ⁺ -Cl – ):(Na ⁺ -HCO 3 – ) pair are identified in this work via the regression of thermodynamic, calorimetric, and phase equilibria experimental data. The binary interaction parameters associated with the H 2 O:(Na ⁺ -Cl – ) pair, the CO 2 :(Na ⁺ -Cl – ) pair, the H 2 O:(Ca ²⁺ -Cl – ) pair, and the (Na ⁺ -Cl – ):(Ca ²⁺ -Cl – ) pair are retrieved from the literature. The remaining binary interaction parameters are retrieved from Aspen Plus or set to zero. In addition, the solubility product constants are identified for Na 2 CO 3 ·10H 2 O (s) , Na 2 CO 3 · 7H 2 O (s) , Na 2 CO 3 ·H 2 O (s) , Na 2 CO 3 ·NaHCO 3 2H 2 O (s) , Na 2 CO 3 ·3NaHCO 3 (s) , and CaCO 3(s) via regression of solubility data. Here, the model is capable of accurately calculating all phase equilibria and calorimetric properties at temperatures up to 473.15 K and salt concentrations up to saturation.

42 ENGINEERING↗
DOE OSTI2022

Na Promotion of Pt/m-ZrO 2 Catalysts for the Steam Reforming of Formaldehyde

The decomposition selectivity of formaldehyde during steam reforming was explored using unpromoted and sodium promoted Pt/m-ZrO 2 catalysts, and the Na content was varied (0.5%Na, 1%Na, 1.8%Na, 2.5%Na, and 5%Na). In situ DRIFTS experiments during temperature programmed reaction in flowing H 2 O revealed that formaldehyde is adsorbed at reduced defect sites on zirconia, where it is converted to formate species through the addition of labile bridging OH species. Formate species achieve a maximum intensity in the range of 125–175 °C, where only slight changes in intensity are observed. Above this temperature, the formate decomposition reactivity strongly depends on the Na loading, with the optimum loadings being 1.8%Na and 2.5%Na. CO 2 temperature programmed desorption results, as well as a greater splitting observed between the formate ν asym (OCO) and ν sym (OCO) bands in infrared spectroscopy, indicate greater basicity is induced by the presence of Na. This strengthens the interaction between the formate -CO 2 functional group and the catalyst surface, weakening the formate C-H bond. A shift in the ν(CH) band of formate to lower wavenumbers was observed by addition of Na, especially at 1.8%Na and higher loadings. This results in enhanced decarboxylation and dehydrogenation of formate, as observed in in situ DRIFTS, temperature-programmed reaction/mass spectrometry experiments of the steam reforming of formaldehyde, and fixed bed reaction tests. For example, 2.5%Na addition of 2.5% increased the CO 2 selectivity from 83.5% to 99.5% and the catalysts achieved higher stable conversion at lower temperature than NiO catalysts reported in the open literature. At 5%Na loading, Pt sites were severely blocked, hindering H-transfer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Mask-side Hyper-NA EUV imaging on the SHARP microscope

Hyper-NA, the prospective successor to high-numerical aperture (NA) extreme ultraviolet lithography (EUVL) could be inserted soon after 2030. Hyper-NA poses a number of challenges, including reduced depth of focus, amplified mask three-dimensional effects, and increased mask-side angular range. A Hyper-NA capable extreme ultraviolet (EUV) mask-imaging tool can address these challenges and accelerate research and development toward Hyper-NA. The Sharp High-Numerical Aperture Actinic Reticle Review Project (SHARP) EUV mask microscope is supporting mask-side high-NA imaging since 2015. Implementing mask-side Hyper-NA imaging in 2024 enables research and development toward the corresponding nodes of EUVL. Hyper-NA zoneplates at 0.75 4x/8x NA with a 6.7-deg chief ray angle and 0.85 4x/8x NA with a 7.4-deg chief ray angle are added to the SHARP microscope. Imaging at mask-side Hyper-NA is demonstrated. Imaging of 5-nm half-pitch (wafer scale) horizontal lines and spaces is demonstrated using dipole illumination. Imaging of 5-nm half-pitch (wafer scale) vertical lines and spaces is demonstrated using frequency-doubled imaging of 40-nm hp (mask scale) lines and spaces. Normalized image log slope (NILS) and modulation of Hyper-NA image data match closely to simulations for horizontal lines and spaces. A reduction in NILS of 0.3 or less is observed for vertical lines and spaces in the two-beam imaging regime. Through-focus image data are discussed, comparing different dipole sources and mask-side NAs. Mask-side Hyper-NA photomask imaging has been implemented and demonstrated on the SHARP microscope and is now available to users of the instrument.

Benk, Markus↗
DOE OSTI2020

Materials Data on Na(Mg4Al3)4 by Materials Project

Na(Mg4Al3)4 is Bergman Structure: Mg32(Al,Zn)49 Bergman-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Na is bonded in a 12-coordinate geometry to eight Mg and five Al atoms. There are a spread of Na–Mg bond distances ranging from 3.09–3.64 Å. There are a spread of Na–Al bond distances ranging from 3.01–3.18 Å. There are ten inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.08–3.17 Å. There are a spread of Mg–Al bond distances ranging from 2.92–3.18 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to four Mg and twelve Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.13–3.15 Å. There are a spread of Mg–Al bond distances ranging from 3.15–3.22 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to one Na, three Mg, and six Al atoms. Both Mg–Mg bond lengths are 3.06 Å. There are a spread of Mg–Al bond distances ranging from 3.06–3.14 Å. In the fourth Mg site, Mg is bonded in a 11-coordinate geometry to one Na, four Mg, and six Al atoms. Both Mg–Mg bond lengths are 3.06 Å. There are a spread of Mg–Al bond distances ranging from 3.09–3.11 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to one Na, six Mg, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.07–3.20 Å. There are a spread of Mg–Al bond distances ranging from 2.93–3.25 Å. In the sixth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.15–3.17 Å. There are a spread of Mg–Al bond distances ranging from 2.92–3.19 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to one Na, six Mg, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.15–3.18 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.22 Å. In the eighth Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. Both Mg–Mg bond lengths are 3.06 Å. There are a spread of Mg–Al bond distances ranging from 3.06–3.13 Å. In the ninth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. The Mg–Mg bond length is 3.13 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.20 Å. In the tenth Mg site, Mg is bonded in a 12-coordinate geometry to one Na, six Mg, and five Al atoms. There are a spread of Mg–Al bond distances ranging from 2.95–3.18 Å. There are seven inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are one shorter (2.69 Å) and two longer (2.77 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to one Na, seven Mg, and three Al atoms. There are a spread of Al–Al bond distances ranging from 2.72–2.77 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are a spread of Al–Al bond distances ranging from 2.70–2.78 Å. In the fourth Al site, Al is bonded in a distorted q6 geometry to one Na, seven Mg, and three Al atoms. There are one shorter (2.69 Å) and one longer (2.79 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. The Al–Al bond length is 2.77 Å. In the sixth Al site, Al is bonded in a 11-coordinate geometry to one Na, seven Mg, and three Al atoms. In the seventh Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na by Materials Project

Na is alpha Samarium structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to twelve Na atoms to form a mixture of corner, edge, and face-sharing NaNa12 cuboctahedra. There are six shorter (3.70 Å) and six longer (3.76 Å) Na–Na bond lengths. In the second Na site, Na is bonded to twelve Na atoms to form a mixture of corner, edge, and face-sharing NaNa12 cuboctahedra. There are three shorter (3.70 Å) and six longer (3.76 Å) Na–Na bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na by Materials Project

Na is alpha La structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to twelve Na atoms to form a mixture of edge, corner, and face-sharing NaNa12 cuboctahedra. There are six shorter (3.69 Å) and six longer (3.73 Å) Na–Na bond lengths. In the second Na site, Na is bonded to twelve Na atoms to form a mixture of edge, corner, and face-sharing NaNa12 cuboctahedra. All Na–Na bond lengths are 3.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na by Materials Project

Na crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 8-coordinate geometry to eight Na atoms. There are a spread of Na–Na bond distances ranging from 3.47–3.75 Å. In the second Na site, Na is bonded in a 8-coordinate geometry to eight Na atoms. Both Na–Na bond lengths are 3.68 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na by Materials Project

Na crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to twelve equivalent Na atoms to form a mixture of face and edge-sharing NaNa12 cuboctahedra. All Na–Na bond lengths are 3.77 Å. In the second Na site, Na is bonded in a 6-coordinate geometry to six Na atoms. Both Na–Na bond lengths are 3.37 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na by Materials Project

Na is beta structured and crystallizes in the cubic P4_132 space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to twelve Na atoms to form a mixture of face, edge, and corner-sharing NaNa12 cuboctahedra. There are a spread of Na–Na bond distances ranging from 3.71–3.86 Å. In the second Na site, Na is bonded to twelve Na atoms to form a mixture of distorted face, edge, and corner-sharing NaNa12 cuboctahedra. All Na–Na bond lengths are 3.41 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Molecular structure and catalytic promotional effect of Mn on supported Na 2 WO 4 /SiO 2 catalysts for oxidative coupling of methane (OCM) reaction

The structure and promotional effect of Mn in supported Mn-Na 2 WO 4 /SiO 2 catalysts for the oxidative coupling of methane (OCM) reaction has been debated for a longtime in the literature. In the current investigation, with the aid of multiple in-situ characterization studies, we show that the freshly calcined supported 1.2Mn-5Na 2 WO 4 /SiO 2 catalyst possesses crystalline Na 2 WO 4 , Mn 2 O 3 and SiO 2 (cristobalite phase) along with surface MnO x and Na-WO x sites at low temperature and oxidizing environments. Under the OCM reaction environment (T>800°C), the crystalline Na 2 WO 4 phase melts and Mn 2 O 3 phase reduces. In contrast, the surface MnO x and Na-WO x sites exhibit excellent thermal and chemical stability. Exposure of the 1.2Mn-5Na 2 WO 4 /SiO 2 catalyst to the OCM reaction environment redisperses the molten Na 2 WO 4 phase on the SiO 2 support to form new surface WO x sites. Interestingly, the stable MnO x species interacts with both molten Na 2 WO 4 phase and surface Na-WO x sites during OCM reaction. Controlled transient kinetic experiments in TAP and detailed steady state OCM fixed-bed reaction studies reveal the role and promotional effect of Mn in the 1.2Mn-5Na 2 WO 4 /SiO 2 catalyst. The W-oxides (both molten Na 2 WO 4 and surface Na-WO x sites) are the active sites for the catalytic OCM reaction and the MnO x species only function as promoters. The promotion of MnO x strongly depends on the gas phase O 2 partial pressure and the MnO x species act as mediators for oxygen exchange between the gas phase molecular O 2 and catalyst lattice oxygen. In conclusion, the temperature dependent MnO x promotion reveals that the MnO x species selectively promote the molten Na 2 WO 4 phase at lower reaction temperature and the surface Na-WO x sites at higher temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Structure Tuning, Strong Second Harmonic Generation Response, and High Optical Stability of the Polar Semiconductors Na 1- x K x AsQ 2

We report the mixed cation compounds Na 1-x K x AsSe 2 (x = 0.8, 0.65, 0.5) and Na 0.1 K 0.9 AsS 2 crystallize in the polar noncentrosymmetric space group Cc. The AAsQ(2) (A = alkali metals, Q = S, Se) family features one-dimensional (1D) 1 / ∞ [AQ 2 - ] chains comprising corner-sharing pyramidal AQ 3 units in which the packing of these chains is dependent on the alkali metals. The parallel 1 / ∞ [AQ(2) - ] chains interact via short As ∙∙∙Se contacts, which increase in length when the fraction of K atoms is increased. The increase in the As ∙∙∙Se interchain distance increases the band gap from 1.75 eV in γ-NaAsSe 2 to 2.01 eV in Na 0.35 K 0.65 AsSe 2 , 2.07 eV in Na 0.2 K 0.8 AsSe 2 , and 2.18 eV in Na 0.1 K 0.9 AsS 2 . The Na 1-x K x AsSe 2 (x = 0.8, 0.65) compounds melt congruently at approximately 316 °C. Wavelength-dependent second harmonic generation (SHG) measurements on powder samples of Na 1-x K x AsSe 2 (x = 0.8, 0.65, 0.5) and Na 0.1 K 0.9 AsS 2 suggest that Na 0.2 K 0.8 AsSe 2 and Na 0.1 K 0.9 AsS 2 have the highest SHG response and exhibit significantly higher laser-induced damage thresholds (LIDTs). Theoretical SHG calculations on Na 0.5 K 0.5 AsSe 2 confirm its SHG response with the highest value of d 33 = 22.5 pm/V χ 333 (2) = 45.0 pm/V). The effective nonlinearity for a randomly oriented powder is calculated to be d eff = 18.9 pm/V χ eff (2) = 37.8 pm/V), which is consistent with the experimentally obtained value of d eff = 16.5 pm/V χ eff (2) = 33.0 pm/V). Three-photon absorption is the dominant mechanism for the optical breakdown of the compounds under intense excitation at 1580 nm, with Na 0.2 K 0.8 AsSe 2 exhibiting the highest stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Flux-assisted polytypism in the [Na 2 Cl]GaQ 2 heterolayered salt-inclusion chalcogenide family

Two polytypic heterolayered salt-inclusion chalcogenides, o-[Na 2 Cl]GaQ 2 and t-[Na 2 Cl]GaQ 2 , were obtained via a NaCl/NaI flux-assisted synthesis, as part of an investigation of the Na–Ga–Q (Q = S and Se) system. The use of a different flux, NaBr/NaI, in the Na–Ga–Se system did not lead to the formation of salt-inclusion phases, but instead the novel Na 2 GaSe 3 and Na 4 Ga 2 Se 5 phases were obtained. Thermal and electronic properties of [Na 2 Cl]GaS 2 materials were investigated with differential scanning calorimetry, post-quenching ex situ powder X-ray diffraction (PXRD), high-temperature PXRD, and enthalpy and electronic structure calculations via density functional theory. Those studies determined the absence of any temperature-induced phase transition between the o-[Na 2 Cl]GaS 2 and t-[Na 2 Cl]GaS 2 polytypic compounds. Moreover, herein we probed the suitability of the heterolayered [Na 2 Cl]GaS 2 single crystals as a sorbent for UO 2 2+ uptake and monitored this process by energy-dispersive and infrared spectroscopies and PXRD, which revealed that the [Na 2 Cl]+ insert could be exchanged with UO 2 2+ on the surface while the UO 2 2+ intercalation decomposes the [Na 2 Cl]GaS 2 structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Na(LiSi2)3 by Materials Project

Na(LiSi2)3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na is bonded in a 12-coordinate geometry to four Li and eight Si atoms. There are two shorter (3.08 Å) and two longer (3.12 Å) Na–Li bond lengths. There are a spread of Na–Si bond distances ranging from 3.13–3.32 Å. There are three inequivalent Li sites. In the first Li site, Li is bonded in a 4-coordinate geometry to two equivalent Na and five Si atoms. There are a spread of Li–Si bond distances ranging from 2.68–2.96 Å. In the second Li site, Li is bonded in a 4-coordinate geometry to two equivalent Na and six Si atoms. There are a spread of Li–Si bond distances ranging from 2.55–2.94 Å. In the third Li site, Li is bonded in a 7-coordinate geometry to nine Si atoms. There are a spread of Li–Si bond distances ranging from 2.62–3.06 Å. There are six inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to five Li and four Si atoms. There are three shorter (2.41 Å) and one longer (2.45 Å) Si–Si bond lengths. In the second Si site, Si is bonded in a 7-coordinate geometry to one Na, two equivalent Li, and four Si atoms. There are two shorter (2.39 Å) and one longer (2.45 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 7-coordinate geometry to one Na, two equivalent Li, and four Si atoms. There are two shorter (2.38 Å) and one longer (2.45 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded in a 9-coordinate geometry to two equivalent Na, five Li, and two equivalent Si atoms. In the fifth Si site, Si is bonded in a 8-coordinate geometry to two equivalent Na, three Li, and three Si atoms. In the sixth Si site, Si is bonded in a 8-coordinate geometry to two equivalent Na, three equivalent Li, and three Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Elastic NaxMoS2-carbon-BASE triple interface direct robust solid-solid interface for all-solid-state Na-S batteries

The promises of all-solid-state (ASS) sodium batteries for the next generation energy storage are widely recognized but their developments have been severely constrained by the difficulties to design favorable solid-solid interfaces for unhindered Na-ion transport. Using the most promising ß?-Al2O3 solid state electrolyte (BASE) as a platform, we demonstrate here a triple nanojunction strategy that provides simultaneous strong Na adhesion and continuous Na-ions diffusion at solid-solid interface. Such triple junctions (NaxMoS2-carbon-BASE) were constructed by adhering ternary composite Na anodes containing dispersed 3 wt% MoS2 and 3 wt% carbon on BASE, and provide nearly complete adhesion of Na on BASE with a much smaller contact angle (~ 45o vs. 120o of pristine Na). The composite Na anodes exhibited ~ 3 times improved elastic property and the synergy of NaxMoS2 and carbon provides the required ionic and electronic diffusion channels at solid-solid interface, which significantly improve Na utilization and resist premature failure due to loss of solid-solid contact as Na shrink during high capacity stripping. As a result, Na metal at the triple junction exhibited more than five time reduced charge transfer resistance and at least 200 hours stable battery cycling at practical current densities. The novel anode architecture also enabled high capacity cycling of prototype ASS sodium sulfur batteries when coupled with advanced sulfur cathodes containing intrinsic Na-ions diffusion channels and redox catalytic mediators, leading to stable cycling with specific capacity of 1110 mAh g-1.

ß”-Al2O3 solid electrolyte, solid state batteries,↗
DOE OSTI2023

A New Sodium Thioborate Fast Ion Conductor: Na 3 B 5 S 9

Abstract We report a new sodium fast‐ion conductor, Na 3 B 5 S 9 , that exhibits a high Na ion total conductivity of 0.80 mS cm −1 (sintered pellet; cold‐pressed pellet=0.21 mS cm −1 ). The structure consists of corner‐sharing B 10 S 20 supertetrahedral clusters, which create a framework that supports 3D Na ion diffusion channels. The Na ions are well‐distributed in the channels and form a disordered sublattice spanning five Na crystallographic sites. The combination of structural elucidation via single crystal X‐ray diffraction and powder synchrotron X‐ray diffraction at variable temperatures, solid‐state nuclear magnetic resonance spectra and ab initio molecular dynamics simulations reveal high Na‐ion mobility (predicted conductivity: 0.96 mS cm −1 ) and the nature of the 3D diffusion pathways. Notably, the Na ion sublattice orders at low temperatures, resulting in isolated Na polyhedra and thus much lower ionic conductivity. This highlights the importance of a disordered Na ion sublattice—and existence of well‐connected Na ion migration pathways formed via face‐sharing polyhedra—in dictating Na ion diffusion.

Zhou, Laidong↗