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At least 1,693 records · Page 94
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Mn(CoO2)2 by Materials Project

MnCo2O4 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Mn2+ is bonded to four equivalent O2- atoms to form MnO4 tetrahedra that share corners with twelve equivalent CoO6 octahedra. The corner-sharing octahedral tilt angles are 59°. All Mn–O bond lengths are 2.03 Å. Co3+ is bonded to six equivalent O2- atoms to form CoO6 octahedra that share corners with six equivalent MnO4 tetrahedra and edges with six equivalent CoO6 octahedra. All Co–O bond lengths are 2.04 Å. O2- is bonded to one Mn2+ and three equivalent Co3+ atoms to form a mixture of distorted edge and corner-sharing OMnCo3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn(GaS2)2 by Materials Project

MnGa2S4 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three MnGa2S4 sheets oriented in the (0, 0, 1) direction. Mn2+ is bonded to four S2- atoms to form MnS4 tetrahedra that share corners with three equivalent GaS6 octahedra and corners with six equivalent MnS4 tetrahedra. The corner-sharing octahedral tilt angles are 61°. There are three shorter (2.33 Å) and one longer (2.44 Å) Mn–S bond lengths. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to six S2- atoms to form GaS6 octahedra that share corners with three equivalent MnS4 tetrahedra, corners with three equivalent GaS4 tetrahedra, and edges with six equivalent GaS6 octahedra. There are three shorter (2.48 Å) and three longer (2.58 Å) Ga–S bond lengths. In the second Ga3+ site, Ga3+ is bonded to four S2- atoms to form GaS4 tetrahedra that share corners with three equivalent GaS6 octahedra and corners with six equivalent GaS4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are one shorter (2.28 Å) and three longer (2.36 Å) Ga–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a trigonal non-coplanar geometry to three equivalent Mn2+ atoms. In the second S2- site, S2- is bonded in a trigonal non-coplanar geometry to three equivalent Ga3+ atoms. In the third S2- site, S2- is bonded to one Mn2+ and three equivalent Ga3+ atoms to form distorted corner-sharing SMnGa3 tetrahedra. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Ga3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn(N3O8)2 by Materials Project

MnO8N2(NO2)4 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four ammonia molecules; eight hydroxylamine, n-hydroxy- molecules; and two MnO8 clusters. In each MnO8 cluster, Mn2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Mn–O bond distances ranging from 1.97–2.39 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Mn2+ and one O2- atom. The O–O bond length is 1.33 Å. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Mn2+ and one O2- atom. The O–O bond length is 1.23 Å. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Mn2+ and one O2- atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn(AlS2)2 by Materials Project

MnAl2S4 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Mn2+ is bonded to four equivalent S2- atoms to form MnS4 tetrahedra that share corners with twelve equivalent AlS6 octahedra. The corner-sharing octahedral tilt angles are 58°. All Mn–S bond lengths are 2.39 Å. Al3+ is bonded to six equivalent S2- atoms to form AlS6 octahedra that share corners with six equivalent MnS4 tetrahedra and edges with six equivalent AlS6 octahedra. All Al–S bond lengths are 2.44 Å. S2- is bonded to one Mn2+ and three equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing SMnAl3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn(SbO3)2 by Materials Project

MnSb2O6 is zeta iron carbide-derived structured and crystallizes in the trigonal P-31m space group. The structure is three-dimensional. Mn2+ is bonded to six equivalent O2- atoms to form MnO6 octahedra that share corners with twelve equivalent SbO6 octahedra. The corner-sharing octahedral tilt angles are 52°. All Mn–O bond lengths are 2.29 Å. Sb5+ is bonded to six equivalent O2- atoms to form SbO6 octahedra that share corners with six equivalent MnO6 octahedra and edges with three equivalent SbO6 octahedra. The corner-sharing octahedral tilt angles are 52°. All Sb–O bond lengths are 2.02 Å. O2- is bonded in a distorted trigonal planar geometry to one Mn2+ and two equivalent Sb5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn(BiTe2)2 by Materials Project

Bi2MnTe4 is MAX Phase-like structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three Bi2MnTe4 sheets oriented in the (0, 0, 1) direction. Mn2+ is bonded to six equivalent Te2- atoms to form MnTe6 octahedra that share corners with six equivalent BiTe6 octahedra, edges with six equivalent MnTe6 octahedra, and edges with six equivalent BiTe6 octahedra. The corner-sharing octahedral tilt angles are 9°. All Mn–Te bond lengths are 2.94 Å. Bi3+ is bonded to six Te2- atoms to form BiTe6 octahedra that share corners with three equivalent MnTe6 octahedra, edges with three equivalent MnTe6 octahedra, and edges with six equivalent BiTe6 octahedra. The corner-sharing octahedral tilt angles are 9°. There are three shorter (3.07 Å) and three longer (3.31 Å) Bi–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Bi3+ atoms. In the second Te2- site, Te2- is bonded to three equivalent Mn2+ and three equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing TeMn3Bi3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn(CO3)2 by Materials Project

MnO2(CO2)2 is Cyanogen Chloride-like structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of eight carbon dioxide molecules and four manganese hydroxide (mn(oh)2) molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Origin of Electrochemical Activation Leading to Enhanced Cycling Stability of Li‐ and Mn‐Rich Cathodes

Electrochemical activation is a critical step for optimal functioning of Li- and Mn-rich (LMR) cathodes, yet the underlying mechanism for such activation remains elusive. Here, by using scanning/transmission electron microscopy (S/TEM) combined with the associated energy-dispersive x-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS), we decipher the origin of the activation enhanced electrochemical properties. We reveal that activation induces the formation of a spinel-like phase within the C2/m domains of the LMR cathode, where the transition-metal ions partially occupy both the tetrahedral (8a) and octahedral (16c) sites of the $Fd\bar{3}m$ spinel lattice, distinguishing the spinel-like phase from the conventional high-voltage spinel. Systematic varying the cycling voltage reveals a critical activation voltage above which this spinel-like phase forms, while lower voltages preserve the layered bulk structure. As the spinel-like phase is a stable structure for electrochemical cycling, the present findings provide direct mechanistic insight into the voltage-dependent activation process and explain how the C2/m to spinel-like transformation upon activation contributes to the electrochemical performance of LMR cathodes, providing guidance for the rational design of Li-rich cathodes with enhanced cycling durability.

Li-rich and Mn-rich cathode↗
DOE OSTI2022

A creep-resistant additively manufactured Al-Ce-Ni-Mn alloy

Existing additively manufactured aluminum alloys exhibit poor creep resistance due to coarsening of their strengthening phases and refined grain structures. In this paper, we report on a novel additively manufactured Al-10.5Ce-3.1Ni-1.2Mn wt.% alloy which displays excellent creep resistance relative to cast high-temperature aluminum alloys at 300–400 °C. In this work, the creep resistance of this alloy is attributed to a high volume fraction (~35%) of submicron intermetallic strengthening phases which are coarsening-resistant for hundreds of hours at 350 °C. The results herein demonstrate that additive manufacturing provides opportunities for development of creep-resistant aluminum alloys that may be used in bulk form in the 250–400 °C temperature range. Pathways for further development of such alloys are identified.

36 MATERIALS SCIENCE↗
DOE OSTI2022

TiO x -supported Na-Mn-W oxides for the oxidative coupling of methane

Supported Na-Mn-W oxides are among the most studied catalysts for the oxidative coupling of methane (OCM) because of their superior thermal stability and relatively high C 2+ product yields. However, because of the structural complexity, the roles of each component in these catalysts have been controversial. In this work, WO x and MnO x sites were supported on titanate nanowires and employed in OCM studies. Compared to the commonly studied silica support, which is subject to severe restructuring due to the Na-induced crystallization, titanate support not only serves as a reservoir for alkali metals (e.g., Na), but also stabilizes isolated MnO x species. The catalytic performance of the titanate-based catalyst is similar to that of reference catalyst, MnO x /Na 2 WO 4 /SiO 2 , with a synergistic effect between MnO x and WO x sites. Further, advanced electron microscopy, X-ray diffraction, infrared spectroscopy, and X-ray absorption near edge structure spectroscopy suggest that the basic NaO x and MnO x species have strong interactions with the acidic WO x and TiO x species, which might contribute to the high selectivity toward C 2+ products and suppressed CO x formation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Microstructural evolution and strengthening mechanisms in a heat-treated additively manufactured Al–Cu–Mn–Zr alloy

In this report the microstructural and strength evolution of an additively manufactured Al-8.6Cu-0.5Mn-0.9Zr alloy upon aging at 300, 350, and 400 °C is investigated. The strengthening phases of the alloy evolve significantly upon aging, with breakdown and spheroidization of the interconnected θ-Al 2 Cu network, dissolution of metastable θ'-Al 2 Cu precipitates, and precipitation of nanometric L1 2 -Al 3 Zr from a matrix supersaturated in Zr. In the peak-aged states, the alloy displays a favorable combination of strength and ductility, with a room-temperature yield strength of 314–341 MPa and ductility of 11–13%. The measured yield strengths for microstructures with different aging treatments are compared to predictions of yield strengths from grain boundary, solid solution, and particle strengthening contributions. The observed strain hardening behavior is related to fundamental precipitate and dislocation interactions. Comparison between predicted and measured strength values indicates a continued need for strengthening models specifically developed for the heterogeneous microstructures of additively manufactured alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Rapid photooxidation and removal of As(III) from drinking water using Fe-Mn composite oxide

Fe-Mn composite oxide (FMO) is widely applied to the oxidation and removal of As(III) from water. However, As(III) can directly reduce manganese oxides, decreasing the oxidation capacity or reusability and thereby greatly limiting the applicability of FMO. Here, the oxidation capacity and reusability of FMO for As(III) were efficiently improved by light radiation, and the effect of typical coexisting ions (SO 4 2– and Ca 2+ ) on the removal of As(III) was also studied. O 2 •– produced from excited manganese oxide and ligand-to-metal charge transfer in iron oxide-As(III) complex enhanced As(III) oxidation and removal under light radiation. At an initial As(III) concentration of 1000 μg L –1 , the total As concentration was respectively decreased to 11.5, 1.5 and 4.4 μg L –1 under darkness, UV light and sunlight at 180 min, and could be reduced to below the guideline limitation of drinking water (10 μg L –1 ) within 40 and 60 min under UV light and sunlight, respectively. SO 4 2– exhibited negligible effect on As removal efficiency because FMO had obviously lower adsorption capacity and selectivity for SO 4 2– than for As(V). The adsorption of coexisting Ca 2+ on manganese oxide decreased the negative charge on the FMO surface, thereby improving As(III) adsorption and oxidation. FMO exhibited excellent reusability, and a total As removal efficiency of 99.1% was still maintained after five cycles of an adsorption-desorption process under UV light. Finally, this work elucidates the photochemical oxidation and removal mechanism of FMO for As(III), and proposes a low-cost and efficient method for the detoxification of As(III)-contaminated drinking water.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Fundamental Insight into Zr Modification of Li- and Mn-Rich Cathodes: Combined Transmission Eelctron Microscopy and Electrochemical Impedance Spectroscopy Study

Zr surface modification was performed on Li- and Mn-rich (LMR) cathode material (Li1.2Ni0.13Co0.13Mn0.54O2) to suppress the detrimental phase transformation upon cycling and enhance its electrochemical performance. Using a wet chemical method, a Zr-based rock-salt layer with a thickness of 1~2 nm was formed on the surface of the LMR. Controlled studies reveal that the Zr-based layers can effectively suppress the phase transformation, leading to an enhanced long-term cycling performance and rate capability. At C/3, the Zr-modified LMR material was found to deliver an initial discharge specific capacity of 211 mAh g-1, and maintain a capacity of 182 mAh g-1 after 100 cycles. Even at high rates of 1, 2 and 3C, it still displays high discharge capacities of 178, 156 and 143 mAh g-1, respectively. This work reports for the first time the detailed mechanisms at atomic scale of how Zr modification can be effectively used to tailor the surface microstructures of high energy cathode materials to improve their long-term stability and cycle life.

Li- and Mn-rich cathode, Li1.2Ni0.13Co0.13Mn0.54O2↗
DOE OSTI2023

Pressure-Dependent Magnetic Properties of Quasi-2D Cr 2 Si 2 Te 6 and Mn 3 Si 2 Te 6

Recently, pressure has been used to induce structural and magnetic phase transitions in many layered quantum materials whose layers are linked by van der Waals forces. Materials with such weakly held layers allow for relatively easy manipulation of the superexchange mechanism, which can give rise to novel magnetic behavior. Here, using hydrostatic pressure as a disorderless means to manipulate the interlayer coupling, we applied pressure on two quasi-2D sister compounds, namely, Cr 2 Si 2 Te 6 (CST) and Mn 3 Si 2 Te 6 (MST), up to ~1 GPa. Magnetic property measurements with the application of pressure revealed that the ferromagnetic transition temperature decreases in CST, while the opposite occurs for the ferrimagnetic MST. In MST, magnetization decreases with the increase in pressure, and such a trend is not clearly observed within the pressure range studied for CST. The overall pressure effect on magnetic characteristics such as exchange couplings and magnetic anisotropy energies is also examined theoretically using density functional theory. Exchange coupling in MST is strongly frustrated, and the first nearest neighbor interaction is the most dominant of the components with the strongest pressure dependence. In CST, the exchange coupling parameters exhibit very little dependence on pressure. This combined experimental and theoretical work has the potential to expand to other relevant quantum materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Rare-Earth-Free Permanent Magnets for Electrical Vehicle Motors and Wind Turbine Generators: Hexagonal Symmetry Based Materials Systems Mn-Bi and M-type Hexaferrite

The research we conducted focuses on the rare-earth (RE)-free permanent magnet by modeling, simulating, and synthesizing exchange coupled two-phase (hard/soft) RE-free core-shell nano-structured magnet. The RE-free magnets are made of magnetically hard core materials (high anisotropy materials including Mn-Bi-X and M-type hexaferrite) coated by soft shell materials (high magnetization materials including Fe-Co or Co). Therefore, our research helps understand the exchange coupling conditions of the core/shell magnets, interface exchange behavior between core and shell materials, formation mechanism of core/shell structures, stability conditions of core and shell materials, etc.

25 ENERGY STORAGE↗
DOE OSTI2019

Processing of Dilute Mg–Zn–Mn–Ca Alloy/Nb Multilayers by Accumulative Roll Bonding

Recent advancements in the severe plastic deformation process called accumulative roll bonding (ARB) can help to address the long-standing need for manufacturing lightweight, high-strength Mg sheet materials. However, the fabrication of Mg alloy-based laminates via ARB remains a challenge due to the intrinsically poor formability of Mg. Herein, it is shown that Mg-based composite laminates with refined layers can be fabricated via several room-temperature ARB cycles with appropriate intermediate annealing and alloy selection. The final laminates made here consist of equal volume fractions of a dilute Mg–Zn–Mn–Ca alloy phase and a pure Nb phase with fine 150 μm layer thicknesses. Deformation texture evolution in both phases within the composite is analyzed via neutron diffraction measurements taken at different stages in the process. The analysis suggests that the annealing step recrystallizes the Mg-alloy phase. It is also shown that for both phases, the stabilized deformation textures within the composite correspond to the classic stable textures of the individual constituents. Polycrystal texture modeling implies that {10–12} <-1011> extension twinning developed in the Mg alloy during rolling.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Optimization of Processing, Microstructure, and Hardness of an Al–Ce–Ni–Mn–Zr Alloy With Laser Additive Manufacturing

Here, this study examines the processing behavior, microstructure, surface roughness, and hardness properties of an aluminum alloy containing 8.2 Ce, 4.5 Ni, 0.5 Mn, and 0.7 Zr (wt%) fabricated using laser powder bed fusion. Sixty samples were produced across a range of laser powers, scan speeds, and hatch spacings to evaluate their effect on porosity, hardness, and microstructural features. Porosity was measured using X-ray computed tomography, while microstructure and surface roughness were characterized by scanning electron (SEM) and laser confocal microscopy. High dense and cracking-free Al–Ni–Ce alloy was successfully manufactured. Porosity showed a U-shaped dependence on energy input, increasing under both insufficient and excessive melting conditions. Hardness increased with cooling rate due to finer cellular structures and solute redistribution. A general statistical model was developed to capture the relationships between processing parameters and material response. Results identify a narrow processing window defined by laser powers between 350 and 370 W, scan speeds from 1400 to 1800 mm/s, and hatch distances between 0.14 and 0.18 mm. Within this window, porosity is minimized (below 0.01%) and hardness is maximized (up to 160 HV), demonstrating that careful control of these parameters enables dense, high strength aluminum components suitable for demanding structural applications.

Aluminum alloys↗
DOE OSTI2022

Anomalous Thermal Decomposition Behavior of Polycrystalline LiNi 0.8 Mn 0.1 Co 0.1 O 2 in PEO-Based Solid Polymer Electrolyte

we report that replacing liquid electrolytes (LEs) with polymer electrolytes has been considered a promising approach to developing next-generation lithium-ion batteries (LIBs) with high energy density and superior safety. Nevertheless, compared with the extensive research on the electrochemical stability of the cathode/polymer electrolyte interfaces, reports on their thermal behaviors are rare to date. Herein, this work systematically investigates the thermal stability of two typical layered oxide cathodes, LiCoO 2 (LCO) and LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811), with poly(ethylene oxide) (PEO) electrolyte and with carbonate LEs, respectively. It is found that the oxygen release from the cathodes plays a central role in thermal runaway. Replacing the LE with PEO electrolyte can considerably improve the thermal stability of LCO, but surprisingly, deteriorate that of NMC811. The reason is that the surface of single-crystalline LCO particles can be effectively passivated by the PEO electrolyte during heating, but PEO cannot sufficiently passivate all the primary particles of NMC811 owing to insufficient interface wettability of PEO electrolyte within the polycrystalline secondary NMC811 particles. The findings in this work collectively formulate valuable guidance for improving the safety of polymer-electrolyte-based as well as other types of all-solid-state lithium-ion batteries.

25 ENERGY STORAGE↗