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Li, Jun

Publications and source records attributed to Li, Jun.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

2018 Annual Site Environmental Report Sandia National Laboratories, New Mexico

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the United States Department of Energy (DOE) National Nuclear Security Administration. The National Nuclear Security Administration's Sandia Field Office administers the contract and oversees contractor operations at Sandia National Laboratories, New Mexico. Activities at the site support research and development programs with a wide variety of national security missions, resulting in technologies for nonproliferation, homeland security, energy and infrastructure, and defense systems and assessments. DOE and its management and operating contractor for Sandia are committed to safeguarding the environment reassessing sustainability practices and ensuring the validity and accuracy of the monitoring data presented in this Annual Site Environmental Report. This report summarizes the environmental protection and monitoring programs in place at Sandia National Laboratories, New Mexico, during calendar year 2018. Environmental topics include air quality, ecology, environmental restoration, oil storage, site sustainability, terrestrial surveillance, waste management, water quality, and implementation of the National Environmental Policy Act. This report is prepared in accordance with and as required by DOE O 231.1B, Admin Change 1, Environment, Safety, and Health Reporting and has been approved for public distribution.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Destruction of the Uranyl Moiety in a U(V) “Cation–Cation” Interaction

A gas-phase uranyl peroxide dimer supported by three 12-crown-4 ether (12C4) ligands, [(UO 2 ) 2 (O 2 )(12C4) 3 )] 2+ (A), was prepared by electrospray ionization. Density functional theory (DFT) indicates a structure with two terminal 12C4 and the third 12C4 bridging the uranium centers. Collision induced dissociation (CID) of A resulted in elimination of the bridging 12C4 to yield a uranyl peroxide dimer with two terminal donor ligands, [(12C4)(UO 2 )(O 2 )(UO 2 )(12C4)] 2+ (B). Remarkably, CID of B resulted in elimination of the bridging peroxide concomitant with reduction of U(VI) to U(V) in C, [(12C4)(UO 2 )(UO 2 )(12C4)] 2+ . DFT studies indicate that in C there is direct interaction between the two UO2+ species, which can thus be considered as a so-called cation-cation interaction (CCI). This formal CCI, induced by tetradentate 12C4 ligands, corresponds to destruction of the linear uranyl moieties and creation of bridging U-O-U oxo-bonds. Finally, on the basis of the structural rearrangement to achieve the structurally extreme CCI interaction, it is predicted also to be accessible for PaO 2 + but is less feasible for transuranic actinyls.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Discharge Permit-1845 Quarterly Status Report July 2019

Discharge Permit (DP)-1845 was issued by the New Mexico Environment (NMED) Ground Water Quality Bureau (GWQB) for discharges via up to three injection wells in a phased Treatability Study of in-situ bioremediation of groundwater at the Sandia National Laboratories, New Mexico, Technical Area-V Groundwater Area of Concern. This report fulfills the quarterly reporting requirements set forth in DP-1845, Section IV.B, Monitoring and Reporting. The reporting period is January 1 through March 31, 2019. All applicable terms and conditions were met for this reporting period. The report is due to NMED GWQB by August 1, 2019.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Photoelectron–Photofragment Coincidence Studies on the Dissociation Dynamics of the OH–CH 4 Complex

Photoelectron-photofragment coincidence (PPC) spectroscopy was used to characterize the energetics and dynamics of the OH + CH 4 → H 2 O + CH 3 reaction initiated by photodetachment of the OH – (CH 4 ) anion complex. PPC measurements at a photon energy of 3.20 eV yielded stable (OH-CH 4 + e – ) and dissociative (OH + CH 4 (ν 1 or ν 3 , v = 0, 1) + e – ) channels. The main channel is dissociation to OH + CH 4 + e – with a low kinetic energy release (KER), peaking at 0.04 eV. Interpretation of the experimental results was supported by quantum chemistry and quasiclassical trajectory calculations. Here, the anion potential energy surface was constructed at the correlated coupled cluster singles, doubles, and perturbative triples level with augmented correlation consistent polarized valence triple-zeta basis set, and previously calculated neutral potential energy surfaces were used. Quasiclassical simulation of the dynamics of the OH-CH 4 complex was carried out by selecting the momenta and coordinates from the Wigner distribution for the anion, providing the starting point for 4000 trajectories on the neutral potential energy surface. In agreement with the experimental results, most of the trajectories yield slowly recoiling OH + CH 4 reactants while some are trapped in the entrance channel van der Waals well.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Structure and Bonding in [Sb@In 8 Sb 12 ] 3− and [Sb@In 8 Sb 12 ] 5−

Abstract We report the characterization of the compound [K([2.2.2]crypt)] 4 [In 8 Sb 13 ], which proves to contain a 1:1 mixture of [Sb@In 8 Sb 12 ] 3− and [Sb@In 8 Sb 12 ] 5− . The tri‐anion displays perfect T h symmetry, the first completely inorganic molecule to do so, and contains eight equivalent In 3+ centers in a cube. The gas‐phase potential energy surface of the penta‐anion has eight equivalent minima where the extra pair of electrons is localized on one In + center, and these minima are linked by low‐lying transition states where the electron pair is delocalized over two adjacent centers. The best fit to the electron density is obtained from a model where the structure of the 5− cluster lies close to the gas‐phase transition state.

Liu, Chao↗
DOE OSTI2019

Fast lithium growth and short circuit induced by localized-temperature hotspots in lithium batteries

Fast-charging and high-energy-density batteries pose significant safety concerns due to high rates of heat generation. Understanding how localized high temperatures affect the battery is critical but remains challenging, mainly due to the difficulty of probing battery internal temperature with high spatial resolution. Here we introduce a method to induce and sense localized high temperature inside a lithium battery using micro-Raman spectroscopy. We discover that temperature hotspots can induce significant lithium metal growth as compared to the surrounding lower temperature area due to the locally enhanced surface exchange current density. More importantly, localized high temperature can be one of the factors to cause battery internal shorting, which further elevates the temperature and increases the risk of thermal runaway. This work provides important insights on the effects of heterogeneous temperatures within batteries and aids the development of safer batteries, thermal management schemes, and diagnostic tools.

25 ENERGY STORAGE↗
DOE OSTI2019

Structure and Bonding in [Sb@In 8 Sb 12 ] 3– and [Sb@In 8 Sb 12 ] 5–

We report the characterization of the compound [K([2.2.2]crypt)] 4 [In 8 Sb 13 ], which proves to contain a 1:1 mixture of [Sb@In 8 Sb 12 ] 3– and [Sb@In 8 Sb 12 ] 5– . The tri–anion displays perfect T h symmetry, the first completely inorganic molecule to do so, and contains eight equivalent In 3+ centers in a cube. The gas–phase potential energy surface of the penta–anion has eight equivalent minima where the extra pair of electrons is localized on one In+ center, and these minima are linked by low–lying transition states where the electron pair is delocalized over two adjacent centers. In conclusion, the best fit to the electron density is obtained from a model where the structure of the 5– cluster lies close to the gas–phase transition state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Encapsulating phosphorus inside carbon nanotubes via a solution approach for advanced lithium ion host

Conventional phosphorus anode materials in lithium/sodium-ion batteries are mainly based on the physical mixing and evaporation/condensation, in which external phosphorus on conductive matrix is unavoidable and hard to be removed due to the formation of crystalline phase. It has been found to break off from conductive matrix easily and deteriorate capacity rapidly. In this communication, we first report a solution processed encapsulation method which facilitates phosphorus anchored inside multi-walled carbon nanotubes (MWCNTs). Any possible external phosphorus adsorbents are hard to transform into crystalline and enable an easy removal by polar solvents. Eventually, the phosphorus rings and chains are successfully encapsulated only inside MWCNTs, exhibiting high cycling stability in lithium-ion battery because of the efficient physical confinement and unique discrete phosphorus segment assemblies inside MWCNTs which ensured enough vacant space for volume expansion.

25 ENERGY STORAGE↗
DOE OSTI2019

Discharge Permit-1845 (Quarterly Report)

Discharge Permit (DP)-1845 was issued by the New Mexico Environment (NMED) Ground Water Quality Bureau (GWQB) for discharges via up to three injection wells in a phased Treatability Study of in-situ bioremediation of groundwater at the Sandia National Laboratories, New Mexico, Technical Area-V Groundwater Area of Concern. This report fulfills the quarterly reporting requirements set forth in DP-1845, Section IV.B, Monitoring and Reporting. This reporting period is October 1 through December 31, 2018. The report is due to NMED GWQB by May 1, 2019.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Seed-Mediated Growth of Au Nanospheres into Hexagonal Stars and the Emergence of a Hexagonal Close-Packed Phase

Gold (Au) typically crystallizes in a cubic close-packed ( ccp ) structure to present a face-centered cubic ( fcc ) lattice or crystal phase. Herein, we demonstrate that Au nanoscale hexagonal stars featuring a hexagonal close-packed (hcp) structure can be synthesized in an aqueous system in the presence of fcc -Au nanospheres as the seeds. The success of this synthesis critically relies on the use of ethylenediaminetetraacetic acid to complex with Au 3+ ions (the precursor) and the introduction of 2-phospho-l-ascorbic acid trisodium salt (Asc-2P) as a novel reducing agent to maneuver the reduction kinetics. The use of Asc-2P favorably promotes the formation of hexagonal stars with uneven surfaces at the top and bottom faces, together with concave side faces around the edges. By varying the amount of Asc-2P to fine-tune the reduction kinetics, we can adjust the concaveness of the side faces, with a faster reduction rate favoring greater concaveness and a red shift of the plasmon resonance peak to the near-infrared. For the first time, our results suggest that the phosphate and hydroxyl groups can act synergistically in controlling the morphology of Au nanocrystals. Most significantly, the newly deposited Au atoms can also crystallize in an hcp structure, leading to the observation of a phase transition from fcc to hcp along the growth direction. This new protocol based upon kinetic control can be potentially extended to other noble metals for the facile synthesis of nanocrystals featuring unprecedented structures or phases.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Charge-Lattice Coupling in Hole-Doped LuFe 2 O 4 + δ : The Origin of Second-Order Modulation

Understanding singularities in ordered structures, such as dislocations in lattice modulation and solitons in charge ordering, offers great opportunities to disentangle the interactions between the electronic degrees of freedom and the lattice. Specifically, a modulated structure has traditionally been expressed in the form of a discrete Fourier series with a constant phase and amplitude for each component. We report atomic scale observation and analysis of a new modulation wave in hole-doped ${\mathrm{LuFe}}_{2}{\mathrm{O}}_{4+{\delta}}$ that requires significant modifications to the conventional modeling of ordered structures. This new modulation with an unusual quasiperiodic singularity can be accurately described only by introducing a well-defined secondary modulation vector in both the phase and amplitude parameter spaces. Correlated with density-functional-theory (DFT) calculations, our results reveal that those singularities originate from the discontinuity of lattice displacement induced by interstitial oxygen in the system. The approach of our work is applicable to a wide range of ordered systems, advancing our understanding of the nature of singularity and modulation.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Rate coefficients and branching ratio for multi-channel hydrogen abstractions from CH 3 OH by F

The hydrogen abstraction reaction F+CH 3 OH has two possible reaction pathways: HF+CH 3 O and HF+CH 2 OH. Despite the absence of intrinsic barriers for both channels, the former has a branching ratio comparable to the latter, which is far from the statistical limit of 0.25 (one out of four available H atoms). Furthermore, the measured branching ratio of the two abstraction channels spans a large range and is not quantitatively reproduced by previous theoretical predictions based on the transition-state theory with the stationary point information calculated at the levels of Møller-Plesset perturbation theory and G2. This work reports a theoretical investigation on the kinetics and the associated branching ratio of the two competing channels of the title reaction using a quasi-classical trajectory approach on an accurate full-dimensional potential energy surface (PES) fitted by the permutation invariant polynomial-neural network approach to ca. 1.21x10 5 points calculated at the explicitly correlated (F12a) version of coupled cluster singles doubles and perturbative triples (CCSD(T)) level with the aug-cc-pVDZ basis set. The calculated room temperature rate coefficient and branching ratio of the HF+CH 3 O channel are in good agreement with the available experimental data. Furthermore, our theory predicts that rate coefficients have a slightly negative temperature dependence, consistent with barrierless nature of the reaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Preparation and Dewatering Property of Two Sludge Conditioners Chitosan/AM/AA and Chitosan/AM/AA/DMDAAC

Two new chitosan-grafting copolymers (chitosan-g-PAM-AA and C-chitosan-g-PAM-AA) as sludge conditioners (flocculation and aggregation) have been prepared by employing ceric sulfate as a free radical initiator under nitrogen atmosphere in aqueous solution. The optimum condition for synthesizing chitosan-grafting copolymer was determined by orthogonal experiments. The structure, morphology and property of the obtained graft polymers were characterized by FT-IR, XRD, SEM, TGA and contact angle. Further, the municipal activated sludge dewatering performance of the synthesized copolymers was evaluated by the filter cake moisture content. Herein, the effects of pH value and dewatering temperatures of activated sludge, loading dosage or cationic degree of C-chitosan-g-PAM-AA on the filter cake moisture content were investigated. The synthesized amphoteric flocculant C-chitosan-g-PAM-AA showed a highly effective flocculation capability for activated sludge compared with chitosan-g-PAM-AA, chitosan, polyacrylamide (PAM). Also, the lowest filter cake moisture content was up to 61.41%.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗