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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na(CO)3 by Materials Project

Na(CO)3 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.50–2.91 Å. There are two inequivalent C+1.67+ sites. In the first C+1.67+ site, C+1.67+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.26 Å. In the second C+1.67+ site, C+1.67+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.26 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Na1+ and one C+1.67+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Na1+ and one C+1.67+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Impact of structural distortions on the correlated electronic structure of orbital-selective Mott insulating Na 3 ⁢Co 2 ⁢SbO 6 under strain

Na 3 Co 2 SbO 6 is a promising candidate to realize the Kitaev spin liquid phase since the large Kitaev spin exchange interaction is tunable via the change in electronic structure, such as the trigonal crystal field splitting (Δ TCF ). Here, in this study, we show that the uncorrelated electronic structure of Na 3 Co 2 SbO 6 is rather insensitive to the strain effect due to the low crystal symmetry accompanied by oxygen displacements and the presence of Sb s orbitals. Using density functional theory plus dynamical mean field theory, we find that the correlated electronic structure of Na 3 Co 2 SbO 6 is an orbital-selective Mott insulating state where the trigonal a 1g orbital is insulating due to the nearly full occupation, while other d orbitals behave as typical Mott insulators, resulting in the effective tunability of Δ TCF under the strain effect. The sign change of Δ TCF can occur as the in-plane tensile strain is applied, and the Kitaev spin liquid phase could possibly be realized due to the strongly suppressed Δ TCF under tensile strain. Our results show that the local Co-site symmetry and dynamical correlation effects will play an important role in engineering the novel magnetic phase in this and related materials.

Nguyen, Nam [Univ. of Illinois, Chicago, IL (Unite↗
DOE OSTI2024

In-plane multi-q magnetic ground state of Na 3 Co 2 SbO 6

We report Na 3 Co 2 SbO 6 is a potential Kitaev magnet with a monoclinic layered crystal structure. Recent investigations of the C3-symmetric sister compound Na 2 Co 2 TeO 6 have uncovered a unique triple-q magnetic ground state, as opposed to a single-q (zigzag) one, prompting us to examine the influence of the reduced structural symmetry of Na 3 Co 2 SbO 6 on its ground state. Neutron diffraction data obtained on a twin-free crystal reveal that the ground state remains a multi-q state, despite the system's strong non-C 3 -symmetric anisotropy. This robustness of multi-q orders suggests that they are driven by a common mechanism in the honeycomb cobaltates, such as interactions beyond the bilinear order. Spin-polarized neutron diffraction results show that the ordered moments are entirely in plane, with each staggered component orthogonal to the propagating wave vector. The inferred ground state appears more compatible with the so-called XXZ easy-plane anisotropy than the Kitaev anisotropy, and features unequal ordered moments reduced by strong quantum fluctuations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Electronic structure of Co 3 d states in the Kitaev material candidate honeycomb cobaltate Na 3 Co 2 SbO 6 probed with x-ray dichroism

The recent prediction that honeycomb lattices of Co 2+ (3d 7 ) ions could host dominant Kitaev interactions provides an exciting direction for exploration of new routes to stabilizing Kitaev’s quantum spin liquid in real materials. Na 3 Co 2 SbO 6 has been singled out as a potential material candidate provided that spin and orbital moments couple into a J eff = $\frac{1}{2}$ ground state, and that the relative strength of trigonal crystal field and spin-orbit coupling acting on Co ions can be tailored. Using x-ray linear dichroism (XLD) and x-ray magnetic circular dichroism (XMCD) experiments, alongside configuration interaction calculations, we confirm the counterintuitive positive sign of the trigonal crystal field acting on Co 2+ ions and test the validity of the J eff = $\frac{1}{2}$ description of the electronic ground state. Furthermore, the results lend experimental support to recent theoretical predictions that a compression (elongation) of CoO 6 octahedra along (perpendicular to) the trigonal axis would drive this cobaltate toward the Kitaev limit, assuming the J eff = $\frac{1}{2}$ character of the electronic ground state is preserved.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Pressure tuning of Kitaev spin liquid candidate Na 3 Co 2 SbO 6

The search for Kitaev’s quantum spin liquid in real materials has recently expanded with the prediction that honeycomb lattices of divalent, high-spin cobalt ions could host the dominant bond-dependent exchange interactions required to stabilize the elusive entangled quantum state. The layered honeycomb Na 3 Co 2 SbO 6 has been singled out as a leading candidate provided that the trigonal crystal field acting on Co 3d orbitals, which enhances non-Kitaev exchange interactions between $J$ eff = $\frac{1}{2}$ spin-orbital pseudospins, is reduced. Here we show that applied pressure leads to anisotropic compression of the layered structure, significantly reducing the trigonal distortion of CoO 6 octahedra. Ferromagnetic correlations between pseudospins are enhanced in the spin-polarized (3 Tesla) phase up to about 60 GPa. Higher pressures drive a high-spin to low-spin transition destroying the $J$ eff = $\frac{1}{2}$ moments required to map the spin Hamiltonian into Kitaev’s model. The spin transition strongly suppresses the low-temperature magnetic susceptibility and appears to stabilize a paramagnetic phase driven by frustration. The possible emergence of frustrated magnetism of localized $S$ = $\frac{1}{2}$ moments opens the door for exploration of novel magnetic quantum states in compressed honeycomb lattices of divalent cobaltates.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Pressure tuning of Kitaev spin liquid candidate Na$_3$Co$_2$SbO$_6$goo

The search for Kitaev's quantum spin liquid (KQSL) state in real materials has recently expanded with the prediction that honeycomb lattices of divalent, high-spin cobalt ions could host the dominant bond-dependent exchange interactions required to stabilize the elusive entangled quantum state. The layered honeycomb Na$_3$Co$_2$SbO$_6$ has been singled out as a leading candidate provided that the trigonal crystal field acting on Co $3d$ orbitals, which enhances non-Kitaev exchange interactions between $J_{\rm eff}=\frac{1}{2}$ spin-orbital pseudospins, is reduced. We find that applied pressure leads to anisotropic compression of the layered structure, significantly reducing the trigonal distortion of CoO$_6$ octahedra. A strong enhancement of ferromagnetic correlations between pseudospins is observed in the spin-polarized (3 Tesla) phase up to about 60 GPa. Higher pressures drive a spin transition into a low-spin state destroying the $J_{\rm eff}=\frac{1}{2}$ local moments required to map the spin Hamiltonian into Kitaev's model. The spin transition strongly suppresses the low-temperature magnetic susceptibility and appears to stabilize a paramagnetic phase driven by frustration. Although applied pressure fails to realize a KQSL state, the possible emergence of frustrated magnetism of localized, low-spin $S=\frac{1}{2}$ moments opens the door for exploration of novel magnetic quantum states in compressed honeycomb lattices of divalent cobaltates.

FOS: Physical sciences↗
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 OSTI2024

High-temperature Raman spectroscopy of K 2 Ca(CO 3 ) 2 bütschliite and Na 2 Ca 2 (CO 3 ) 3 shortite

Raman spectra of Na 2 Ca 2 (CO 3 ) 3 shortite and K 2 Ca(CO 3 ) 2 bütschliite were measured to 715°C and 740°C respectively, under vacuum. The vibrational spectra demonstrate that shortite converts to nyerereite (Na 2 Ca(CO 3 ) 2 ) and calcite at 535°C. This assemblage is stable to ~700°C, where nyerereite begins to decompose. Bütschliite converts to the isochemical phase fairchildite at 570°C, which is stable to 665°C, where it decomposes to an assemblage of K 2 CO 3 and CaO. The variation of anharmonicity between different vibrational modes of each of the low temperature phases is assessed, and these yield insights into inter-carbonate group couplings. In conclusion, both fairchildite and nyerereite exhibit spectral features consistent with extensive disordering.

58 GEOSCIENCES↗
DOE OSTI2020

Heterotrimetallic Mixed‐Valent Molecular Precursors Containing Periodic Table Neighbors: Assignment of Metal Positions and Oxidation States

Abstract A known trinuclear structure was used to design the heterobimetallic mixed‐valent, mixed‐ligand molecule [Co II (hfac) 3 −Na−Co III (acac) 3 ] ( 1 ). This was used as a template structure to develop heterotrimetallic molecules [Co II (hfac) 3 −Na−Fe III (acac) 3 ] ( 2 ) and [Ni II (hfac) 3 −Na−Co III (acac) 3 ] ( 3 ) via isovalent site‐specific substitution at either of the cobalt positions. Diffraction methods, synchrotron resonant diffraction, and multiple‐wavelength anomalous diffraction were applied beyond simple structural investigation to provide an unambiguous assignment of the positions and oxidation states for the periodic table neighbors in the heterometallic assemblies. Molecules of 2 and 3 are true heterotrimetallic rather than a statistical mixture of two heterobimetallic counterparts. Trinuclear platform 1 exhibits flexibility in accommodating a variety of di‐ and trivalent metals, which can be further utilized in the design of molecular precursors for the NaMM′O 4 functional oxide materials.

Han, Haixiang↗
DOE OSTI2022

Salt-Assisted 2H-to-1T' Phase Transformation of Transition Metal Dichalcogenides [plus supplemental information]

Phase engineering of nanomaterials (PEN) has demonstrated great potential in the fields of catalysis, electronics, energy storage and conversion, and condensed matter physics. Recently, transition metal dichalcogenides (TMDs) with unconventional metastable phases (e.g., 1T and 1T') have attracted increasing research interest due to their unique and appealing physicochemical properties. However, there is still a lack of a simple, universal, and controlled method for the preparation of large-scale and high-purity unconventional-phase TMD crystals, restricting their further fundamental study and practical applications. Here, a facile, one-step salt-assisted general strategy is reported for the controlled phase transformation of commercially available TMDs with conventional 2H phase, yielding a large amount of metastable 1T'-phase TMDs, including WS 2 , WSe 2 , MoS 2 , and MoSe 2 . It is found that the easily accessible metal salts, such as K 2 C 2 O 4 ·H 2 O, K 2 CO 3 , Na 2 CO 3 , Rb 2 CO 3 , Cs 2 CO 3 , KHCO 3 , NaHCO 3 , and NaC 2 O 4 , can be used to assist the 2H-to-1T' phase transformation, greatly simplifying the synthetic process for producing metastable 1T'-TMDs. Importantly, this method can also be used to prepare 1T'-TMD alloys, such as 1T'-WS 2x Se 2(1–x) . We report this newly developed strategy is robust and highly effective, which can also be used for the phase engineering of other materials with various polymorphs.

1T′ phase↗
DOE OSTI2024

Molten‐Salt‐Mediated Chemical Looping Oxidative Dehydrogenation of Ethane with In‐Situ Carbon Capture and Utilization

Abstract The molten‐salt‐mediated oxidative dehydrogenation (MM‐ODH) of ethane (C 2 H 6 ) via a chemical looping scheme represents an effective carbon capture and utilization (CCU) method for the valorization of ethane‐rich shale gas and concurrent mitigation of carbon dioxide (CO 2 ) emissions. Here, stepwise experimentation with Li 2 CO 3 ‐Na 2 CO 3 ‐K 2 CO 3 (LNK) ternary salts (i) assessed how each component of the LNK mixture impacted ethane MM‐ODH performance and (ii) explored physicochemical and thermodynamic mechanisms behind melt‐induced changes to ethylene (C 2 H 4 ) and carbon monoxide (CO) yields. Of fifteen screened LNK compositions, nine exhibited ethylene yields greater than 50 % at 800 °C while maintaining C 2 H 4 selectivities of 85 % or higher. LNK salts rich in Li 2 CO 3 content yielded more ethylene and CO on average than their counterparts, and net CO 2 capture per cycle reached a maximum of ~75 %. Extended MM‐ODH cycling also demonstrated long‐term stability of a high‐performing LNK medium. Density functional theory (DFT) calculations andab initiomolecular dynamics (AIMD) simulations suggested that the molten salt does not directly activate C 2 H 6 . Meanwhile, an empirical model informed by experimental data and reaction thermodynamics adequately predicted overall MM‐ODH performance from LNK composition and provided insights into the system′s primary drivers.

Chemistry↗
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 OSTI2023

Oxygen carrying materials with surface modification for redox-based catalysis and methods of making and uses thereof

Redox catalysts having surface medication, methods of making redox catalysts with surface modification, and uses of the surface modified redox catalysts are provided. In some aspects, the redox catalysts include a core oxygen carrier region such as CaMnO 3 , BaMnO 3−δ , SrMnO 3−δ , Mn 2 SiO 4 , Mn 2 MgO 4−δ , La 0.8 Sr 0.2 O 3−δ , La 0.8 Sr 0.2 FeO 3−δ , Ca 9 Ti 0.1 Mn 0.9 O 3−δ , Pr 6 O 11−δ , manganese ore, or a combination thereof; and an outer shell having an average thickness of about 1-100 monolayers surrounding the outer surface of the core region. The outer shell can include, for example a salt selected such as Li 2 WO 4 , Na 2 WO 4 , K 2 WO 4 , SrWO 4 , Li 2 MoO 4 , Na 2 MoO 4 , K 2 MoO 4 , CsMoO 4 , Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3 , or a combination thereof.

Li, Fanxing↗
DOE OSTI2025

Delta/Lambda Chirality: From Enantiomers to Diastereomers in Heterometallic Complexes with Chelating Ligands

The Δ/Λ chirality observed in octahedral molecules with chelating ligands represents the major group of “chiral-at-metal” complexes. Upon shifting from mononuclear to polynuclear systems with multiple (≥2) chiral centers, not only enantiomers but also diastereomers should be considered. We present the first, to the best of our knowledge, diastereomeric pairs Δ,Δ,Δ/Λ,Λ,Λ (1) and Δ,Δ,Λ/ Λ,Λ,Δ (2) of the pentanuclear assembly [Mn II (ptac) 3 −Na- Co III (acac) 3 −Na-Mn II (ptac) 3 ] (ptac = 1,1,1-trifluoro-5,5-dimethyl- 2,4-hexanedionate; acac = acetylacetonate). Diastereomers 1 and 2 were isolated in pure form and found to exhibit distinctly different structural characteristics. Importantly, for compounds that are applied as single-source precursors for the quaternary oxide cathode material P2−Na 0.67 Mn 0.67 Co 0.33 O 2 , the diastereomers revealed different thermal behaviors in terms of volatility and thermal stability. Unambiguous assignment of the Mn and Co positions in both diastereomers has been confirmed by the synchrotron X-ray resonant diffraction technique. Oxidation states of metal ions have been verified by the synchrotron X-ray fluorescence spectroscopy. The diastereomerization between 1 and 2 is not taking place in the solid state (crystal-to-crystal), as well as in the gas phase. The transformation between two diastereomers was observed in the solutions of noncoordinating solvents and was related to the polarities of the solvents and diastereomeric molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

A new layered kagome strip structure Na 2 Co 3 (AsO 4 ) 2 (OH) 2 : static and dynamic magnetic properties

One-dimensional kagome strip chains share much of the same frustrated structural motif as two-dimensional kagome antiferromagnets, making them valuable for deepening our understanding of kagome lattice magnetism. In this paper, we report the hydrothermal synthesis and detailed structural and property characterization of Na 2 Co 3 (AsO 4 ) 2 (OH) 2 , a striped kagome system. The crystal structure was characterized using single crystal X-ray diffraction which reveals that Na 2 Co 3 (AsO 4 ) 2 (OH) 2 crystallizes in monoclinic crystal system C2/m. The structure features a one-dimensional kagome strip lattice built from Co 2+ ions and undergoes an antiferromagnetic transition at T N = 14 K. The magnetic ground state at zero field was characterized using neutron powder diffraction. Below the magnetic transition, Na 2 Co 3 (AsO 4 ) 2 (OH) 2 orders into an antiferromagnetic structure with a k-vector (0.5, 0.5, 0.5). In the proposed model, the Co1 moment is predominantly confined to the ac-plane while the Co2 moment is primarily aligned along the b-axis. Two flat bands were observed in the inelastic neutron spectra below the magnetic transition, 5 and 10 meV. Inelastic neutron spectra were modeled with a Heisenberg Hamiltonian including three nearest-neighbor exchange interactions (J 1 , J 2 , J 3 ) and strong single-ion anisotropy to stabilize the observed magnetic structure. Our study highlights the complexity of Co 2+ -based kagome strip magnetic lattice compound Na 2 Co 3 (AsO 4 ) 2 (OH) 2 which provides an excellent platform to broaden our understanding of the frustrated kagome magnetic lattice space.

Liurukara, Duminda S. [Oak Ridge National Laborato↗
DOE OSTI2020

Electrochemical studies of a high voltage Na 4 Co 3 (PO 4 ) 2 P 2 O 7 –MWCNT composite through a selected stable electrolyte

Na 4 Co 3 (PO 4 ) 2 P 2 O 7 –MWCNT composites in 1 M NaPF 6 in EC:DMC electrolytes deliver stable discharge capacities of 80 mA h g −1 and 78 mA h g −1 at normal and elevated temperatures, respectively. In a full cell configuration vs. NaTi 2 (PO 4 ) 3 –MWCNT, they deliver an initial discharge capacity of 78 mA h g −1 at 0.2C rate.

25 ENERGY STORAGE↗