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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Aryl Diazonium-Assisted Amidoximation of MXene for Boosting Water Stability and Uranyl Sequestration via Electrochemical Sorption

Despite that two-dimensional transition metal carbides and carbonitrides (MXenes) are burgeoning candidates for remediation of environmental pollutants, the construction of robust functionalized MXene nanosheets with a high affinity for target heavy metal ions and radionuclides remains a challenge. Here we report the successful placement of amidoxime chelating groups on Ti 3 C 2 T x MXene surface by diazonium salt grafting. The introduction of amidoxime functional groups significantly enhances the selectivity of Ti 3 C 2 T x nanosheets for uranyl ions and also greatly improves their stability in aqueous solution, enabling efficient, rapid, and recyclable uranium extraction from aqueous solutions containing competitive metal ions. Benefiting from the excellent conductivity of MXenes, the amidoxime functionalized Ti 3 C 2 T x nanosheets show outstanding electrochemical performance such that when loaded on carbon cloth the application of an electric field increases the uranium adsorption capacity from 294 to 626 mg/g, outperforming all organic electrochemical sorption materials reported previously. Finally, the present work provides an effective strategy to functionalize MXene nanosheets with fundamental implications for the design of MXene-based selective electrosorption electrode materials.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

Synthesis of Mo 4 VAlC 4 MAX Phase and Two-Dimensional Mo 4 VC 4 MXene with Five Atomic Layers of Transition Metals

MXenes are a family of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides with a general formula of M n+1 X n T x , in which two, three, or four atomic layers of a transition metal (M: Ti, Nb, V, Cr, Mo, Ta, etc.) are interleaved with layers of C and/or N (shown as X), and T x represents surface termination groups such as –OH, =O, and –F. Here, we report the scalable synthesis and characterization of a MXene with five atomic layers of transition metals (Mo 4 VC 4 T x ), by synthesizing its Mo 4 VAlC 4 MAX phase precursor that contains no other MAX phase impurities. These phases display twinning at their central M layers which is not present in any other known MAX phases or MXenes. Transmission electron microscopy and X-ray diffraction were used to examine the structure of both phases. Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and high-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy were used to study the composition of these materials. Density functional theory calculations indicate that other five transition metal-layer MAX phases (M' 4 M"AlC 4 ) may be possible, where M' and M" are two different transition metals. The predicted existence of additional Al-containing MAX phases suggests that more M 5 C 4 T x MXenes can be synthesized. Additionally, we characterized the optical, electronic, and thermal properties of Mo 4 VC 4 T x . Here, this study demonstrates the existence of an additional subfamily of M 5 X 4 T x MXenes as well as a twinned structure, allowing for a wider range of 2D structures and compositions for more control over properties, which could lead to many different applications.

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

A stable atmospheric-pressure plasma for extreme-temperature synthesis

Plasmas can generate ultra-high-temperature reactive environments that can be used for the synthesis and processing of a wide range of materials. However, the limited volume, instability and non-uniformity of plasmas have made it challenging to scalably manufacture bulk, high-temperature materials. Here we present a plasma set-up consisting of a pair of carbon-fibre-tip-enhanced electrodes that enable the generation of a uniform, ultra-high temperature and stable plasma (up to 8,000 K) at atmospheric pressure using a combination of vertically oriented long and short carbon fibres. The long carbon fibres initiate the plasma by micro-spark discharge at a low breakdown voltage, whereas the short carbon fibres coalesce the discharge into a volumetric and stable ultra-high-temperature plasma. As a proof of concept, we used this process to synthesize various extreme materials in seconds, including ultra-high-temperature ceramics (for example, hafnium carbonitride) and refractory metal alloys. Moreover, the carbon-fibre electrodes are highly flexible and can be shaped for various syntheses. In conclusion, this simple and practical plasma technology may help overcome the challenges in high-temperature synthesis and enable large-scale electrified plasma manufacturing powered by renewable electricity.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

A theoretical investigation of the effect of Ga alloying on thermodynamic stability, electronic-structure, and oxidation resistance of Ti 2 AlC MAX phase

We present a systematic investigation of thermodynamic stability, phase-reaction, and chemical activity of Al containing disordered Ti 2 (Al-Ga)C MAX phases using machine-learning driven high-throughput framework to understand the oxidation resistance behavior with increasing temperature and exposure to static oxygen. The A-site (at Al) disordering of Ti 2 AlC with Ga shows significant change in the chemical activity of Al with increasing temperature and exposure to static oxygen, which is expected to enable surface segregation of Al, thereby, the formation of Al 2 O 3 and improved oxidation resistance. We performed in-depth convex hull analysis of ternary Ti-Al-C, Ti-Ga-C, and Ti-Al-Ga-C based MAX phase, and provide detailed contribution arising from electronic, chemical and vibrational entropies. The thermodynamic analysis shows change in the Gibbs formation enthalpy (ΔG form ) at higher temperatures, which implies an interplay of temperature-dependent enthalpy and entropic contributions in oxidation resistance Ga doped Ti 2 AlC MAX phases. A detailed electronic structure and chemical bonding analysis using crystal orbital Hamilton population method reveal the origin of change in phases stability and in oxidation resistance in disorder Ti2(Al 1-x Ga x )C MAX phases. Our electronic structure analysis correlate well with the change in oxidation resistance of Ga doped MAX phases. We believe our study provides a useful guideline to understand to role of alloying on electronic, thermodynamic, and oxidation related mechanisms of bulk MAX phases, which can work as a precursor to understand oxidation behavior of twodimensional MAX phases, i.e., MXenes (transition metal carbides, carbonitrides and nitrides).

36 MATERIALS SCIENCE↗
DOE OSTI2020

Tunable electrochromic behavior of titanium-based MXenes

Two-dimensional transition metal carbides, nitrides and carbonitrides, popular by the name MXenes, are a promising class of materials as they exhibit intriguing optical, optoelectronic and electrochemical properties. Taking advantage of their metallic conductivity and hydrophilicity, titanium carbide MXenes (Ti 3 C 2 T x and others) are used to fabricate solution processable transparent conducting electrodes (TCEs) for the design of three-electrode electrochromic cells. However, the tunable electrochromic behavior of various titanium-based MXene compositions across the entire visible spectrum has not yet been demonstrated. Here, we investigate the intrinsic electrochromic properties of titanium-based MXenes, Ti 3 C 2 T x , Ti 3 CNT x , Ti 2 CT x , and Ti 1.6 Nb 0.4 CT x , where individual MXenes serve as a transparent conducting, electrochromic, and plasmonic material layer. Plasmonic extinction bands for Ti 3 C 2 T x , Ti 2 CT x and Ti 1.6 Nb 0.4 CT x are centered at 800, 550 and 480 nm, which are electrochemically tunable to 630, 470 and 410 nm, respectively, whereas Ti 3 CNT x shows a reversible change in transmittance in the wide visible range. Additionally, the switching rates of MXene electrodes with no additional transparent conductor electrodes are estimated and correlated with the respective electrical figure of merit values. This work demonstrates that MXene-based electrochromic cells are tunable in the entire visible spectrum and suggests the potential of the MXene family of materials in optoelectronic, plasmonic, and photonic applications, such as tunable visible optical filters and modulators, to name a few.

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

Surface engineering of MXenes for energy and environmental applications

We report MXenes, a new family of two-dimensional (2D) transition-metal carbides, nitrides, and carbonitrides, have received considerable attention in energy and environmental applications due to their intriguing electronic, electrochemical, optical, and chemical properties. Applications of MXenes have been witnessed in photocatalysis, electrocatalysis, thermocatalysis, sensing and biosensing, electrochemical energy storage, energy conversion and storage, rechargeable batteries, supercapacitors, and biomedicine. Notably, the tunable surface chemistry of MXenes plays an important role in their success in those applications. The surface composition of MXenes is considered to have a significant influence on their physicochemical properties and functionalities. In order to achieve a comprehensive understanding and rational design of MXenes by surface engineering, in this review, we highlight the application of several kinds of surface engineering approaches for MXenes, including tuning the surface termination groups, surface functionalization, surface defects, surface doping, surface oxidation, and the theoretical simulation of surface engineering of MXenes. Moreover, the relationship between the surface engineering and the physicochemical properties of MXenes is discussed. Finally, the ongoing challenges and opportunities for the future development of MXene surface engineering are also highlighted.

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

Investigation of kinetic inductance and microwave loss in thin-film TaC x N 1−x superconducting resonators

The promise of tantalum for realizing superconducting quantum devices has generated interest in its compound films, particularly nitrides. Among these, cubic-phase tantalum carbonitride (TaC x N 1−x ) offers reduced susceptibility to oxidation and a high critical temperature, yet its microwave properties remain largely unexplored. Here, in this study, we investigate plasma-enhanced atomic layer deposition of cubic-phase TaC x N 1−x thin films for superconducting microwave circuits. Structural and transport measurements reveal nanocrystalline morphology with sub-10 nm grains and superconductivity in the dirty limit. Coplanar waveguide resonators exhibit moderately high kinetic inductance (16.8 pH/sq for 30 nm films) with potential for enhancement through dimensional scaling. The films also support high internal quality factors exceeding 10 5 at 50 mK in the single-photon regime, comparable to granular aluminum. Loss analysis identifies the two-level systems as the dominant limiting mechanism, with potential for further reduction through interface engineering. These results establish atomic layer deposited TaC x N 1−x as a promising material for scalable, low-loss, high-inductance superconducting circuits.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Tribology and Tribocorrosion of Case-Hardened Steels: A Review

This report reviews the tribological and tribocorrosion performance of steels that are case-hardened via boriding, chromizing, carburizing, nitriding, nitrocarburizing, and carbonitriding. Case-hardening is commonly used to improve the hardness, impact durability, wear resistance, and corrosion resistance of steel alloys and has been successfully applied in various industries, providing a cost-effective, high-throughput solution for applications involving contact and sliding interfaces in complex service environments. This article summarizes the literature results of the wear and friction behavior of common case-hardening methods for steel alloys under various conditions, including corrosive environments. Special attention is given to the influences of case-hardening process parameters and alloy composition on tribological performance. Furthermore, by discussing key findings from the literature, this review provides insights into optimizing case-hardening processes for improving the tribological and tribocorrosion performance of steel alloys.

Alloys↗
DOE OSTI2020

Materials Data on Li4SiO4 by Materials Project

Li4SiO4 is Aluminum carbonitride-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share corners with four LiO5 square pyramids, corners with four equivalent LiO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with two equivalent LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.98–2.10 Å. In the second Li1+ site, Li1+ is bonded to five O2- atoms to form distorted LiO5 square pyramids that share corners with three equivalent LiO5 square pyramids, corners with three LiO4 tetrahedra, corners with three equivalent SiO4 tetrahedra, edges with five LiO5 square pyramids, an edgeedge with one SiO4 tetrahedra, and edges with two equivalent LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.99–2.28 Å. In the third Li1+ site, Li1+ is bonded to five O2- atoms to form distorted LiO5 square pyramids that share corners with three equivalent LiO5 square pyramids, a cornercorner with one SiO4 tetrahedra, corners with five LiO4 tetrahedra, edges with five LiO5 square pyramids, an edgeedge with one LiO4 tetrahedra, and edges with two equivalent SiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 2.02–2.35 Å. In the fourth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share corners with four LiO5 square pyramids, corners with four equivalent LiO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with three LiO5 square pyramids. There are a spread of Li–O bond distances ranging from 1.99–2.03 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four LiO5 square pyramids, corners with eight LiO4 tetrahedra, and edges with three LiO5 square pyramids. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to five Li1+ and one Si4+ atom to form distorted OLi5Si octahedra that share corners with two equivalent OLi5Si octahedra, corners with six equivalent OLi3Si tetrahedra, and edges with six OLi5Si octahedra. The corner-sharing octahedral tilt angles are 14°. In the second O2- site, O2- is bonded to five Li1+ and one Si4+ atom to form distorted OLi5Si octahedra that share corners with four OLi5Si octahedra, corners with two equivalent OLi3Si tetrahedra, and edges with eight OLi5Si octahedra. The corner-sharing octahedra tilt angles range from 14–29°. In the third O2- site, O2- is bonded to five Li1+ and one Si4+ atom to form distorted OLi5Si octahedra that share corners with two equivalent OLi5Si octahedra, corners with two equivalent OLi3Si tetrahedra, and edges with nine OLi5Si octahedra. The corner-sharing octahedra tilt angles range from 15–29°. In the fourth O2- site, O2- is bonded to three Li1+ and one Si4+ atom to form distorted OLi3Si tetrahedra that share corners with ten OLi5Si octahedra and an edgeedge with one OLi3Si tetrahedra. The corner-sharing octahedra tilt angles range from 57–68°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al4C3 by Materials Project

Al4C3 is Aluminum carbonitride-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four equivalent C4- atoms to form a mixture of corner and edge-sharing AlC4 trigonal pyramids. There are three shorter (1.97 Å) and one longer (2.18 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of corner and edge-sharing AlC4 tetrahedra. There are one shorter (1.93 Å) and three longer (2.18 Å) Al–C bond lengths. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CAl6 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 63°. In the second C4- site, C4- is bonded to six equivalent Al3+ atoms to form CAl6 octahedra that share corners with six equivalent CAl5 trigonal bipyramids and edges with six equivalent CAl6 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4Mo(NO)2 by Materials Project

Na4Mo(NO)2 is Aluminum carbonitride-derived structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with four NaN4O square pyramids, corners with four equivalent NaN2O2 tetrahedra, corners with four equivalent MoN2O2 tetrahedra, and edges with two equivalent NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.32–2.42 Å. In the second Na1+ site, Na1+ is bonded to four N3- and one O2- atom to form distorted NaN4O square pyramids that share corners with three equivalent NaN4O square pyramids, a cornercorner with one MoN2O2 tetrahedra, corners with five NaO4 tetrahedra, edges with five NaN4O square pyramids, an edgeedge with one NaN2O2 tetrahedra, and edges with two equivalent MoN2O2 tetrahedra. There are a spread of Na–N bond distances ranging from 2.48–2.68 Å. The Na–O bond length is 2.48 Å. In the third Na1+ site, Na1+ is bonded to four N3- and one O2- atom to form distorted NaN4O square pyramids that share corners with three equivalent NaN4O square pyramids, corners with three NaO4 tetrahedra, corners with three equivalent MoN2O2 tetrahedra, edges with five NaN4O square pyramids, an edgeedge with one MoN2O2 tetrahedra, and edges with two equivalent NaN2O2 tetrahedra. There are a spread of Na–N bond distances ranging from 2.46–2.54 Å. The Na–O bond length is 2.78 Å. In the fourth Na1+ site, Na1+ is bonded to two N3- and two O2- atoms to form distorted NaN2O2 tetrahedra that share corners with four NaN4O square pyramids, corners with four equivalent NaO4 tetrahedra, corners with four equivalent MoN2O2 tetrahedra, and edges with three NaN4O square pyramids. There are one shorter (2.42 Å) and one longer (2.43 Å) Na–N bond lengths. There are one shorter (2.35 Å) and one longer (2.40 Å) Na–O bond lengths. Mo6+ is bonded to two N3- and two O2- atoms to form MoN2O2 tetrahedra that share corners with four NaN4O square pyramids, corners with eight NaO4 tetrahedra, and edges with three NaN4O square pyramids. Both Mo–N bond lengths are 1.82 Å. There is one shorter (1.90 Å) and one longer (1.91 Å) Mo–O bond length. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to five Na1+ and one Mo6+ atom to form distorted NNa5Mo octahedra that share corners with two equivalent ONa3Mo tetrahedra and edges with two equivalent NNa5Mo octahedra. In the second N3- site, N3- is bonded in a 6-coordinate geometry to five Na1+ and one Mo6+ atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Mo6+ atom. In the second O2- site, O2- is bonded to three Na1+ and one Mo6+ atom to form distorted ONa3Mo tetrahedra that share corners with two equivalent NNa5Mo octahedra and an edgeedge with one ONa3Mo tetrahedra. The corner-sharing octahedra tilt angles range from 62–69°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2VGeO5 by Materials Project

Li2VGeO5 is Aluminum carbonitride-derived structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Li1+ is bonded to six O2- atoms to form distorted LiO6 octahedra that share corners with two equivalent LiO6 octahedra, corners with four equivalent GeO4 tetrahedra, and edges with four equivalent LiO6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are four shorter (2.07 Å) and two longer (2.56 Å) Li–O bond lengths. V4+ is bonded in a 5-coordinate geometry to five O2- atoms. There is one shorter (1.68 Å) and four longer (1.99 Å) V–O bond length. Ge4+ is bonded to four equivalent O2- atoms to form GeO4 tetrahedra that share corners with eight equivalent LiO6 octahedra. The corner-sharing octahedral tilt angles are 63°. All Ge–O bond lengths are 1.77 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent Li1+ and one V4+ atom. In the second O2- site, O2- is bonded to two equivalent Li1+, one V4+, and one Ge4+ atom to form a mixture of distorted edge and corner-sharing OLi2VGe tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2VSiO5 by Materials Project

Li2VOSiO4 is Aluminum carbonitride-derived structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Li1+ is bonded to six O2- atoms to form distorted LiO6 octahedra that share corners with two equivalent LiO6 octahedra, corners with four equivalent SiO4 tetrahedra, and edges with four equivalent LiO6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are four shorter (2.08 Å) and two longer (2.47 Å) Li–O bond lengths. V4+ is bonded in a 5-coordinate geometry to five O2- atoms. There is one shorter (1.68 Å) and four longer (1.99 Å) V–O bond length. Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with eight equivalent LiO6 octahedra. The corner-sharing octahedral tilt angles are 61°. All Si–O bond lengths are 1.65 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to four equivalent Li1+ and one V4+ atom. In the second O2- site, O2- is bonded to two equivalent Li1+, one V4+, and one Si4+ atom to form a mixture of distorted edge and corner-sharing OLi2VSi trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4W(NO)2 by Materials Project

Na4W(NO)2 is Aluminum carbonitride-derived structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with four NaN4O square pyramids, corners with four equivalent NaN2O2 tetrahedra, corners with four equivalent WN2O2 tetrahedra, and edges with two equivalent NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.32–2.43 Å. In the second Na1+ site, Na1+ is bonded to four N3- and one O2- atom to form distorted NaN4O square pyramids that share corners with three equivalent NaN4O square pyramids, a cornercorner with one WN2O2 tetrahedra, corners with five NaO4 tetrahedra, edges with five NaN4O square pyramids, an edgeedge with one NaN2O2 tetrahedra, and edges with two equivalent WN2O2 tetrahedra. There are a spread of Na–N bond distances ranging from 2.48–2.68 Å. The Na–O bond length is 2.53 Å. In the third Na1+ site, Na1+ is bonded to four N3- and one O2- atom to form distorted NaN4O square pyramids that share corners with three equivalent NaN4O square pyramids, corners with three NaO4 tetrahedra, corners with three equivalent WN2O2 tetrahedra, edges with five NaN4O square pyramids, an edgeedge with one WN2O2 tetrahedra, and edges with two equivalent NaN2O2 tetrahedra. There are a spread of Na–N bond distances ranging from 2.46–2.54 Å. The Na–O bond length is 2.91 Å. In the fourth Na1+ site, Na1+ is bonded to two N3- and two O2- atoms to form NaN2O2 tetrahedra that share corners with four NaN4O square pyramids, corners with four equivalent NaO4 tetrahedra, corners with four equivalent WN2O2 tetrahedra, and edges with three NaN4O square pyramids. Both Na–N bond lengths are 2.41 Å. There are one shorter (2.37 Å) and one longer (2.40 Å) Na–O bond lengths. W6+ is bonded to two N3- and two O2- atoms to form WN2O2 tetrahedra that share corners with four NaN4O square pyramids, corners with eight NaO4 tetrahedra, and edges with three NaN4O square pyramids. Both W–N bond lengths are 1.85 Å. Both W–O bond lengths are 1.91 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to five Na1+ and one W6+ atom to form distorted NNa5W octahedra that share corners with two equivalent NNa5W octahedra, corners with two equivalent ONa3W tetrahedra, and edges with six NNa5W octahedra. The corner-sharing octahedra tilt angles range from 19–38°. In the second N3- site, N3- is bonded to five Na1+ and one W6+ atom to form distorted NNa5W octahedra that share corners with two equivalent NNa5W octahedra, corners with two equivalent ONa3W tetrahedra, and edges with six NNa5W octahedra. The corner-sharing octahedra tilt angles range from 19–38°. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one W6+ atom. In the second O2- site, O2- is bonded to three Na1+ and one W6+ atom to form distorted ONa3W tetrahedra that share corners with four NNa5W octahedra and an edgeedge with one ONa3W tetrahedra. The corner-sharing octahedra tilt angles range from 62–69°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Yb(FeO2)2 by Materials Project

YbFe2O4 is Aluminum carbonitride-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Yb2+ is bonded to six O2- atoms to form YbO6 octahedra that share corners with six equivalent FeO5 trigonal bipyramids and edges with six equivalent YbO6 octahedra. All Yb–O bond lengths are 2.32 Å. Fe3+ is bonded to five O2- atoms to form distorted FeO5 trigonal bipyramids that share corners with three equivalent YbO6 octahedra, corners with six equivalent FeO5 trigonal bipyramids, and edges with three equivalent FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 60°. There are a spread of Fe–O bond distances ranging from 1.82–2.20 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe4 tetrahedra. In the second O2- site, O2- is bonded to three equivalent Yb2+ and one Fe3+ atom to form distorted OYb3Fe tetrahedra that share corners with thirteen OFe4 tetrahedra and edges with three equivalent OYb3Fe tetrahedra. In the third O2- site, O2- is bonded to three equivalent Yb2+ and one Fe3+ atom to form distorted OYb3Fe tetrahedra that share corners with thirteen OFe4 tetrahedra and edges with three equivalent OYb3Fe tetrahedra. The O–Fe bond length is 1.82 Å. In the fourth O2- site, O2- is bonded to three equivalent Yb2+ and one Fe3+ atom to form distorted OYb3Fe tetrahedra that share corners with thirteen OFe4 tetrahedra and edges with three equivalent OYb3Fe tetrahedra. All O–Yb bond lengths are 2.32 Å. The O–Fe bond length is 1.82 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Lu(FeO2)2 by Materials Project

LuFe2O4 is Aluminum carbonitride-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Lu3+ is bonded to six equivalent O2- atoms to form distorted LuO6 octahedra that share corners with six equivalent FeO5 trigonal bipyramids and edges with six equivalent LuO6 octahedra. There are four shorter (2.24 Å) and two longer (2.26 Å) Lu–O bond lengths. Fe+2.50+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share corners with three equivalent LuO6 octahedra, corners with six equivalent FeO5 trigonal bipyramids, and edges with three equivalent FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 63°. There are a spread of Fe–O bond distances ranging from 2.00–2.18 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Fe+2.50+ atoms to form OFe4 trigonal pyramids that share corners with four equivalent OLu3Fe tetrahedra, corners with six equivalent OFe4 trigonal pyramids, and edges with three equivalent OFe4 trigonal pyramids. In the second O2- site, O2- is bonded to three equivalent Lu3+ and one Fe+2.50+ atom to form OLu3Fe tetrahedra that share corners with nine equivalent OLu3Fe tetrahedra, corners with four equivalent OFe4 trigonal pyramids, and edges with three equivalent OLu3Fe tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(FeO2)2 by Materials Project

ErFe2O4 is Aluminum carbonitride-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Er3+ is bonded to six equivalent O2- atoms to form ErO6 octahedra that share corners with six equivalent FeO5 trigonal bipyramids and edges with six equivalent ErO6 octahedra. All Er–O bond lengths are 2.27 Å. Fe+2.50+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share corners with three equivalent ErO6 octahedra, corners with six equivalent FeO5 trigonal bipyramids, and edges with three equivalent FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. There are a spread of Fe–O bond distances ranging from 1.99–2.16 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Fe+2.50+ atoms to form OFe4 trigonal pyramids that share corners with four equivalent OEr3Fe tetrahedra, corners with six equivalent OFe4 trigonal pyramids, and edges with three equivalent OFe4 trigonal pyramids. In the second O2- site, O2- is bonded to three equivalent Er3+ and one Fe+2.50+ atom to form OEr3Fe tetrahedra that share corners with nine equivalent OEr3Fe tetrahedra, corners with four equivalent OFe4 trigonal pyramids, and edges with three equivalent OEr3Fe tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on In6Ga2PtO8 by Materials Project

PtIn6Ga2O8 is Aluminum carbonitride-derived structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pt2- is bonded to six equivalent In2+ atoms to form PtIn6 octahedra that share corners with twenty-four equivalent OIn3Ga tetrahedra. All Pt–In bond lengths are 2.57 Å. In2+ is bonded in a 5-coordinate geometry to one Pt2- and four equivalent O2- atoms. All In–O bond lengths are 2.30 Å. Ga3+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Ga–O bond lengths are 1.91 Å. O2- is bonded to three equivalent In2+ and one Ga3+ atom to form distorted OIn3Ga tetrahedra that share corners with three equivalent PtIn6 octahedra, corners with six equivalent OIn3Ga tetrahedra, and edges with three equivalent OIn3Ga tetrahedra. The corner-sharing octahedral tilt angles are 62°.

36 MATERIALS SCIENCE↗