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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Cooperative and bifunctional Ga-Ca-Cr 2 O 3 @CaO structured monoliths as versatile platform for reactive capture of CO 2 and its subsequent conversion to ethylene

Cooperative and bifunctional materials (BFMs) that integrate adsorbents and catalysts offer a promising strategy for the reactive capture of CO 2 to produce valuable fuels and chemicals. In this study, we developed structured BFMs via 3D printing that combine CaO as an adsorbent with Ga–Ca–Cr 2 O 3 metal oxides as the catalyst for the reactive capture of CO 2 and its subsequent conversion to C 2 H 4 via the oxidative dehydrogenation of C 2 H 6 (CO 2 -ODHE). Three different Ga–Ca compositions were used to modify the catalyst surface characteristics and enhance C 2 H 4 selectivity. In these formulations, Ga ions stabilize the oxygen lattice of the BFM, while Ca ions interact strongly with Cr to form CaCrO 4 , thereby altering the oxygen species and enhancing the material’s basic properties. Under adsorption–reaction conditions at 600–650 °C, the optimal BFM achieved an excellent C 2 H 4 selectivity of 96.4 %, attributed to a balanced redox process and improved basicity that facilitate efficient C 2 H 6 conversion and rapid desorption of C 2 H 4 without excessive oxidation. Overall, this work provides new insights into the formulation of BFMs monoliths and highlights the critical role of catalytic surface modification in enhancing C 2 H 4 selectivity in the CO 2 -ODHE reactive capture process.

C2H4 production↗
DOE OSTI2020

Materials Data on K4Mo6Se2O33 by Materials Project

K4Mo6Se2O33 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent K sites. In the first K site, K is bonded in a 4-coordinate geometry to five O atoms. There are a spread of K–O bond distances ranging from 2.80–3.37 Å. In the second K site, K is bonded in a distorted square co-planar geometry to four O atoms. There are a spread of K–O bond distances ranging from 2.81–2.86 Å. In the third K site, K is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of K–O bond distances ranging from 2.73–3.44 Å. In the fourth K site, K is bonded in a 5-coordinate geometry to five O atoms. There are a spread of K–O bond distances ranging from 2.74–3.04 Å. There are six inequivalent Mo sites. In the first Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.73–2.40 Å. In the second Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.73–2.39 Å. In the third Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.73–2.39 Å. In the fourth Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.73–2.39 Å. In the fifth Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.72–2.35 Å. In the sixth Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.72–2.34 Å. There are two inequivalent Se sites. In the first Se site, Se is bonded in a tetrahedral geometry to four O atoms. There are a spread of Se–O bond distances ranging from 1.64–1.70 Å. In the second Se site, Se is bonded in a tetrahedral geometry to four O atoms. There are a spread of Se–O bond distances ranging from 1.64–1.70 Å. There are thirty-three inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to one K and one Mo atom. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one K and one Mo atom. In the third O site, O is bonded in a distorted single-bond geometry to one K and one Mo atom. In the fourth O site, O is bonded in a distorted bent 120 degrees geometry to one K and one Mo atom. In the fifth O site, O is bonded in a 3-coordinate geometry to three Mo atoms. In the sixth O site, O is bonded in a 3-coordinate geometry to three Mo atoms. In the seventh O site, O is bonded in a 2-coordinate geometry to three Mo atoms. In the eighth O site, O is bonded in a 3-coordinate geometry to three Mo atoms. In the ninth O site, O is bonded in a distorted bent 150 degrees geometry to one K and one Se atom. In the tenth O site, O is bonded in a distorted bent 150 degrees geometry to one K and one Se atom. In the eleventh O site, O is bonded in a distorted trigonal planar geometry to one K, one Mo, and one Se atom. In the twelfth O site, O is bonded in a distorted trigonal planar geometry to one K, one Mo, and one Se atom. In the thirteenth O site, O is bonded in a distorted trigonal planar geometry to one K, one Mo, and one Se atom. In the fourteenth O site, O is bonded in a distorted trigonal planar geometry to one K, one Mo, and one Se atom. In the fifteenth O site, O is bonded in a 3-coordinate geometry to three Mo atoms. In the sixteenth O site, O is bonded in a 3-coordinate geometry to three Mo atoms. In the seventeenth O site, O is bonded in a 1-coordinate geometry to one K, one Mo, and one Se atom. In the eighteenth O site, O is bonded in a 1-coordinate geometry to one K, one Mo, and one Se atom. In the nineteenth O site, O is bonded in a bent 120 degrees geometry to one K and two O atoms. There is one shorter (1.28 Å) and one longer (1.29 Å) O–O bond length. In the twentieth O site, O is bonded in a distorted L-shaped geometry to one K and one O atom. The O–O bond length is 1.24 Å. In the twenty-first O site, O is bonded in a distorted single-bond geometry to one K and one O atom. In the twenty-second O site, O is bonded in a distorted single-bond geometry to one K and one O atom. In the twenty-third O site, O is bonded in a single-bond geometry to one O atom. In the twenty-fourth O site, O is bonded in a distorted single-bond geometry to one K and one O atom. The O–O bond length is 1.23 Å. In the twenty-fifth O site, O is bonded in a distorted trigonal planar geometry to two K and one Mo atom. In the twenty-sixth O site, O is bonded in a distorted trigonal planar geometry to two K and one Mo atom. In the twenty-seventh O site, O is bonded in a distorted bent 120 degrees geometry to one K and one Mo atom. In the twenty-eighth O site, O is bonded in a distorted bent 120 degrees geometry to one K and one Mo atom. In the twenty-ninth O site, O is bonded in a single-bond geometry to one Mo atom. In the thirtieth O site, O is bonded in a single-bond geometry to one Mo atom. In the thirty-first O site, O is bonded in a single-bond geometry to one Mo atom. In the thirty-second O site, O is bonded in a single-bond geometry to one Mo atom. In the thirty-third O site, O is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Elucidating Actinide–Pertechnetate and Actinide–Perrhenate Bonding via a Family of Th–TcO 4 and Th–ReO 4 Frameworks and Solutions

Technetium-99, a β-emitter produced from 235 U fission, poses a challenge for the nuclear industry due to co-extraction of pertechnetate (TcO 4 – ) with the actinides (An) during nuclear fuel reprocessing. Previous studies suggested that direct coordination of pertechnetate with An plays an important role in the coextraction process. However, few studies have provided direct evidence for An–TcO 4 – bonding in the solid state, and even fewer in solution. The present study describes synthesis and structural elucidation of a family of thorium(IV)-pertechnetate/perrhenate (ReO 4 – , nonradioactive surrogate) compounds, which is obtained by dissolution of thorium oxyhydroxide in perrhenic/pertechnic acid followed by crystallization, with or without heating. For reaction ratios of 3:1, 4:1, and 6:1 MO 4 – /Th(IV) (M = Tc, Re), the crystallized compounds reflect the same ratio, suggesting facile and flexible coordination. Furthermore, nine structures reveal 1-dimensional and 2-dimensional frameworks with varying topologies. While a multitude of compounds isolated from 4:1 (and 6:1) reaction solutions feature Th monomers linked by MO 4 – , the 3:1 reaction solution yielded the well-known dihydroxide-bridged thorium dimer, linked, and capped by MO 4 – . Density functional theory calculations on ReO 4 – /TcO 4 – isomorphs suggest similar bonding characteristics in the solid state, but experimental solution characterization noted differences. Specifically, small-angle X-ray scattering studies suggest the bonding of Th–TcO 4 – persists in solution, while Th–ReO 4 – bonding is less apparent.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2003

Mechanistic Studies Of Combustion And Structure Formation During Combustion Synthesis Of Advanced Materials: Phase Separation Mechanism For Bio-Alloys

Among all implant materials, Co-Cr-Mo alloys demonstrate perhaps the most useful balance of resistance to corrosion, fatigue and wear, along with strength and biocompatibility [1]. Currently, these widely used alloys are produced by conventional furnace technology. Owing to high melting points of the main alloy elements (e.g. Tm.p.(Co) ~1768 K), high-temperature furnaces and long process times (several hours) are required. Therefore, attempts to develop more efficient and flexible methods for production of such alloys with superior properties are of great interest. The synthesis of materials using combustion phenomena is an advanced approach in powder metallurgy [2]. The process is characterized by unique conditions involving extremely fast heating rates (up to 10(exp 6 K/s), high temperatures (up to 3500 K), and short reaction times (on the order of seconds). As a result, combustion synthesis (CS) offers several attractive advantages over conventional metallurgical processing and alloy development technologies. The foremost is that solely the heat of chemical reaction (instead of an external source) supplies the energy for the synthesis. Also, simple equipment, rather than energy-intensive high-temperature furnaces, is sufficient. This work was devoted to experiments on CS of Co-based alloys by utilizing thermite (metal oxide-reducing metal) reactions, where phase separation subsequently produces materials with tailored compositions and properties. Owing to high reaction exothermicity, the CS process results in a significant increase of temperature (up to 3000 C), which is higher than melting points of all products. Since the products differ in density, phase separation may be a gravitydriven process: the heavy (metallic phase) settles while the light (slag) phase floats. The goal was to determine if buoyancy is indeed the major mechanism that controls phase segregation.

Varma, A.↗
DOE OSTI2022

13 C ENDOR Characterization of the Central Carbon within the Nitrogenase Catalytic Cofactor Indicates That the CFe 6 Core Is a Stabilizing “Heart of Steel”

Substrates and inhibitors of Mo-dependent nitrogenase bind and react at Fe ions of the active-site FeMo-cofactor [7Fe–9S–C–Mo–homocitrate] contained within the MoFe protein α-subunit. The cofactor contains a CFe 6 core, a carbon centered within a trigonal prism of six Fe, whose role in catalysis is unknown. Targeted 13 C labeling of the carbon enables electron-nuclear double resonance (ENDOR) spectroscopy to sensitively monitor the electronic properties of the Fe–C bonds and the spin-coupling scheme adopted by the FeMo-cofactor metal ions. Here this report compares 13 CFe 6 ENDOR measurements for (i) the wild-type protein resting state (E 0 ; α-Val 70 ) to those of (ii) α-Ile 70 , (iii) α-Ala 70 -substituted proteins; (iv) crystallographically characterized CO-inhibited “hi-CO” state; (v) E 4 (4H) Janus intermediate, activated for N 2 binding/reduction by accumulation of 4[ e– /H + ]; (vi) E 4 (2H)* state containing a doubly reduced FeMo-cofactor without Fe-bound substrates; and (vii) propargyl alcohol reduction intermediate having allyl alcohol bound as a ferracycle to FeMo-cofactor Fe6. All states examined, both S = 1/2 and 3/2 exhibited near-zero 13 C isotropic hyperfine coupling constants, $^Ca$ = [-1.3 ↔ +2.7] MHz. Density functional theory computations and natural bond orbital analysis of the Fe-C bonds show that this occurs because a (3 spin-up/3 spin-down) spin-exchange configuration of CFe 6 Fe-ion spins produces cancellation of large spin-transfers to carbon in each Fe–C bond. Previous X-ray diffraction and DFT both indicate that trigonal-prismatic geometry around carbon is maintained with high precision in all these states. The persistent structure and Fe–C bonding of the CFe 6 core indicate that it does not provide a functionally dynamic (hemilabile) “beating heart”-instead it acts as “a heart of steel”, stabilizing the structure of the FeMo-cofactor-active site during nitrogenase catalysis.

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

The role of ternary alloying elements in eutectoid transformation of U-10Mo alloy part II. In and Ex-situ Neutron diffraction-based assessment of eutectoid phase transformation kinetics in U-9.8Mo-0.2X alloy (X = Cr, Ni or Co)

HExploring the effects of minor ternary alloying additions, typically impurity elements, on the phase stability of U-10Mo is important for preventing undesirable phase decomposition during processing or during service. This work examines the influence small ternary additions of Cr, Ni, and Co. Both in-situ and ex-situ neutron diffraction measurements made during and after high temperature (450 – 525°C) exposures were used to better define the influence of these elements on the time-temperature-transformation (TTT) behavior of U-10Mo, providing information which is complementary to electron microscopy investigations of the same alloy systems performed in the first part of this work. Minor additions of Ni and Co decrease the ?-phase stability at all temperatures investigated. Signatures of U6X (X = Ni or Co) compounds were shown to be present in amounts of up to 6 wt% in the heat treated alloys, suggesting that the initial precipitation of this phase may catalyze further ?-phase decomposition. On the other hand, the Cr containing alloys were observed to have nearly the same, and in some cases slower, phase transformation kinetics when compared to the binary U-10Mo control samples. The results of the study have enabled preliminary estimates of the TTT curves for the ternary alloys.

phase transformation, kinetics, discontinuous prec↗
DOE OSTI2021

Exploring the Role of the Central Carbide of the Nitrogenase Active-Site FeMo-cofactor through Targeted 13 C Labeling and ENDOR Spectroscopy

Mo-dependent nitrogenase is a major contributor to global biological N 2 reduction, which sustains life on Earth. Its multi-metallic active-site FeMo-cofactor (Fe 7 MoS 9 C-homocitrate) contains a carbide (C 4– ) centered within a trigonal prismatic CFe 6 core resembling the structural motif of the iron carbide, cementite. The role of the carbide in FeMo-cofactor binding and activation of substrates and inhibitors is unknown. Here, to explore this role, the carbide has been in effect selectively enriched with 13 C, which enables its detailed examination by ENDOR/ESEEM spectroscopies. 13 C-carbide ENDOR of the S = 3/2 resting state (E 0 ) is remarkable, with an extremely small isotropic hyperfine coupling constant, C a = +0.86 MHz. Turnover under high CO partial pressure generates the S = 1/2 hi-CO state, with two CO molecules bound to FeMo-cofactor. This conversion surprisingly leaves the small magnitude of the 13 C carbide isotropic hyperfine-coupling constant essentially unchanged, C a = –1.30 MHz. This indicates that both the E 0 and hi-CO states exhibit an exchange-coupling scheme with nearly cancelling contributions to C a from three spin-up and three spin-down carbide-bound Fe ions. In contrast, the anisotropichyperfine coupling constant undergoes a symmetry change upon conversion of E 0 to hi-CO that may be associated with bonding and coordination changes at Fe ions. In combination with the negligible difference between CFe 6 core structures of E 0 and hi-CO, these results suggest that in CO-inhibited hi-CO the dominant role of the FeMo-cofactor carbide is to maintain the core structure, rather than to facilitate inhibitor binding through changes in Fe-carbide covalency or tretching/breaking of carbide–Fe bonds.

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

Materials Data on Na4Co(MoO4)3 by Materials Project

Na4Co(MoO4)3 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.44 Å) and two longer (2.63 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are two shorter (2.58 Å) and two longer (2.63 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.46–2.71 Å. In the fourth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.45–2.50 Å. In the fifth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are four shorter (2.39 Å) and two longer (2.58 Å) Na–O bond lengths. In the sixth Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six MoO4 tetrahedra and an edgeedge with one CoO6 octahedra. There are a spread of Na–O bond distances ranging from 2.26–2.45 Å. There are four inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with two equivalent NaO6 octahedra and corners with two equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 55–58°. There is two shorter (1.77 Å) and two longer (1.84 Å) Mo–O bond length. In the second Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with two equivalent NaO6 octahedra and corners with two equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 53–62°. There is two shorter (1.78 Å) and two longer (1.82 Å) Mo–O bond length. In the third Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with two equivalent NaO6 octahedra and corners with two equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 35–63°. There are a spread of Mo–O bond distances ranging from 1.79–1.81 Å. In the fourth Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with two equivalent NaO6 octahedra and corners with two equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 45–55°. There are a spread of Mo–O bond distances ranging from 1.78–1.84 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six MoO4 tetrahedra and an edgeedge with one NaO6 octahedra. There are a spread of Co–O bond distances ranging from 2.04–2.25 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mo6+, and one Co2+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Mo6+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Mo6+, and one Co2+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Mo6+ atom. In the fifth O2- site, O2- is bonded to three Na1+ and one Mo6+ atom to form distorted ONa3Mo tetrahedra that share corners with two equivalent ONa3Mo tetrahedra, corners with two equivalent ONa2CoMo trigonal pyramids, and an edgeedge with one ONa2CoMo trigonal pyramid. In the sixth O2- site, O2- is bonded to two Na1+, one Mo6+, and one Co2+ atom to form distorted ONa2CoMo trigonal pyramids that share corners with two equivalent ONa3Mo tetrahedra, corners with two equivalent ONa2CoMo trigonal pyramids, and an edgeedge with one ONa3Mo tetrahedra. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mo6+, and one Co2+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Mo6+, and one Co2+ atom. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one Mo6+ atom. In the tenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one Mo6+ atom. In the eleventh O2- site, O2- is bonded in a trigonal planar geometry to two Na1+ and one Mo6+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mo6+, and one Co2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Oligosaccharide production and signaling correlate with delayed flowering in an Arabidopsis genotype grown and selected in high [CO 2 ]

Since industrialization began, atmospheric CO 2 ([CO 2 ]) has increased from 270 to 415 ppm and is projected to reach 800–1000 ppm this century. Some Arabidopsis thaliana (Arabidopsis) genotypes delayed flowering in elevated [CO 2 ] relative to current [CO 2 ], while others showed no change or accelerations. To predict genotype-specific flowering behaviors, we must understand the mechanisms driving flowering response to rising [CO 2 ]. [CO 2 ] changes alter photosynthesis and carbohydrates in plants. Plants sense carbohydrate levels, and exogenous carbohydrate application influences flowering time and flowering transcript levels. We asked how organismal changes in carbohydrates and transcription correlate with changes in flowering time under elevated [CO 2 ]. We used a genotype (SG) of Arabidopsis that was selected for high fitness at elevated [CO 2 ] (700 ppm). SG delays flowering under elevated [CO 2 ] (700 ppm) relative to current [CO 2 ] (400 ppm). We compared SG to a closely related control genotype (CG) that shows no [CO 2 ]-induced flowering change. We compared metabolomic and transcriptomic profiles in these genotypes at current and elevated [CO 2 ] to assess correlations with flowering in these conditions. While both genotypes altered carbohydrates in response to elevated [CO 2 ], SG had higher levels of sucrose than CG and showed a stronger increase in glucose and fructose in elevated [CO 2 ]. Both genotypes demonstrated transcriptional changes, with CG increasing genes related to fructose 1,6-bisphosphate breakdown, amino acid synthesis, and secondary metabolites; and SG decreasing genes related to starch and sugar metabolism, but increasing genes involved in oligosaccharide production and sugar modifications. Genes associated with flowering regulation within the photoperiod, vernalization, and meristem identity pathways were altered in these genotypes. Elevated [CO 2 ] may alter carbohydrates to influence transcription in both genotypes and delayed flowering in SG. Changes in the oligosaccharide pool may contribute to delayed flowering in SG. This work extends the literature exploring genotypic-specific flowering responses to elevated [CO 2 ].

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Materials Data on K10CoMo7O27 by Materials Project

K10Mo7CoO27 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.68–2.96 Å. In the second K1+ site, K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.73–3.42 Å. In the third K1+ site, K1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.62–2.86 Å. In the fourth K1+ site, K1+ is bonded in a 2-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.58–3.19 Å. In the fifth K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.74–3.30 Å. In the sixth K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.68–3.20 Å. There are five inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share a cornercorner with one CoO6 octahedra. The corner-sharing octahedral tilt angles are 33°. There is one shorter (1.78 Å) and three longer (1.81 Å) Mo–O bond length. In the second Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share a cornercorner with one CoO6 octahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of Mo–O bond distances ranging from 1.76–1.86 Å. In the third Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.77–2.26 Å. In the fourth Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share a cornercorner with one CoO6 octahedra. The corner-sharing octahedral tilt angles are 15°. There is three shorter (1.80 Å) and one longer (1.82 Å) Mo–O bond length. In the fifth Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share a cornercorner with one CoO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Mo–O bond distances ranging from 1.76–1.84 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six MoO4 tetrahedra. There are a spread of Co–O bond distances ranging from 2.05–2.18 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to four K1+ and one Mo6+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Mo6+ and one Co2+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to four K1+ and one Mo6+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to four K1+ and one Mo6+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one Mo6+, and one Co2+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to four K1+ and one Mo6+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two Mo6+ and one Co2+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+ and one Mo6+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+, one Mo6+, and one Co2+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Development of Novel Ferritic-Martensitic Steels with Superior Creep Properties for Power Plant Applications

A creep resistant martensitic steel, CPJ-7, was developed with an operating temperature approaching 650°C. Subsequently, another creep resistant martensitic steel, JMP, was designed with the potential to operate at, or slightly above, 650°C. This report describes the development of these alloys from early iterations of CPJ steels to the final CPJ-7 formulation as well as the more heat resistant JMP steel formulation. The design originated from computational modeling for phase stability and precipitate strengthening using fifteen constituent elements. Approximately forty heats of CPJ and ten of JMP, each weighing ~7 kg, were vacuum induction melted. A computationally optimized heat treatment schedule was developed to homogenize the ingots prior to hot forging and rolling prior to final normalization and tempering. Overall, wrought and cast versions of CPJ-7 present superior creep properties when compared to wrought and cast versions of COST alloys for steam turbine and wrought and cast versions of P91/92 for boiler applications. For instance, the Larson Miller Parameter curve for CPJ-7 at 650°C almost coincides with that of COST E at 620°C. The prolonged creep life was attributed to slowing down the process of the destabilization of the MX and M 23 C 6 precipitates at 650°C. On the other hand, the cast version of CPJ-7 also revealed superior mechanical performance, well above commercially available cast 9% Cr martensitic steel or derivatives, especially for creep life at 650°C. The casting process employed slow cooling to simulate the conditions of a thick wall full-size steam turbine casing but utilized a separate homogenization step prior to final normalization and tempering. To advance the development of CPJ-7 for commercial applications, a process was used to scale up the production of the alloy using vacuum induction melting (VIM) and electroslag remelting (ESR), which underlined the importance of melt processing control of intentionally designed minor and trace elements in these advanced alloys. Following the work on CPJ-7, the JMP steels were designed with higher Co for increased solid solution strengthening, Si for oxidation resistance and increased W (with low Mo content) for matrix strength and stability as well as solid solution strengthening. The JMP steels showed increases in creep life compared to CPJ-7 between 118 to 150% at 650°C for testing at various stresses between 138 MPa and 207 MPa. On a Larson-Miller plot, the performance of the JMP steels surpasses that of state-of-the-art MARBN and other MARBN-type steels. The influence of various elements within the composition of the alloys on the microstructure and mechanical properties are discussed. This report presents approximately 420,000 h of in-house creep testing, the equivalent of almost 50 years of cumulative creep tests.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Ni4Mo4(HO4)5 by Materials Project

Na2Mo4Ni4(HO4)5 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.30–2.55 Å. There are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to five O2- atoms to form distorted MoO5 trigonal bipyramids that share a cornercorner with one NiO4 trigonal pyramid, an edgeedge with one NiO6 octahedra, and an edgeedge with one NiO4 trigonal pyramid. There are a spread of Mo–O bond distances ranging from 1.77–2.24 Å. In the second Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.84–2.37 Å. There are three inequivalent Ni+2.25+ sites. In the first Ni+2.25+ site, Ni+2.25+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent NiO4 trigonal pyramids and edges with two equivalent MoO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 2.01–2.21 Å. In the second Ni+2.25+ site, Ni+2.25+ is bonded to four O2- atoms to form distorted NiO4 trigonal pyramids that share a cornercorner with one NiO6 octahedra, a cornercorner with one MoO5 trigonal bipyramid, and an edgeedge with one MoO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 63°. There are a spread of Ni–O bond distances ranging from 1.96–2.01 Å. In the third Ni+2.25+ site, Ni+2.25+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (1.91 Å) and two longer (2.17 Å) Ni–O bond lengths. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.68 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.51 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.22 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ni+2.25+, one H1+, and one O2- atom. The O–O bond length is 1.44 Å. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Mo6+, and one Ni+2.25+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Mo6+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Ni+2.25+ and two H1+ atoms. In the fifth O2- site, O2- is bonded to two Mo6+ and two Ni+2.25+ atoms to form a mixture of distorted corner and edge-sharing ONi2Mo2 trigonal pyramids. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+, one Mo6+, and one O2- atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two equivalent Mo6+ atoms. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Mo6+, and one H1+ atom. In the ninth O2- site, O2- is bonded to two Mo6+ and two Ni+2.25+ atoms to form a mixture of distorted corner and edge-sharing ONi2Mo2 tetrahedra. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+, one Mo6+, and one Ni+2.25+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Data for The utility of transfer learning to improve the performance of deep learning in axon segmentation

The utility of transfer learning to improve the performance of deep learning in axon segmentation Data Data: All the input and labeled volumes tf-logs: Tensorflow logs, view with command "tensorboard --logdir [name of folder]" Model Weights: model_weights: the argument list under variable combo indicate 1) no oversampling, 2) no rotation, 3) no learn scheduler, and 4) flipping on all three dimensions, and the additional values indicate 5) elastic deformation percentage, 6) rotate deformation percentage, 7) layer setting , 8) learning rate, and 9) training/validation/test data division suffix (leave '' if not using suffix). Results: Output from inference segment_total_results_validation_final: All validation results and calculations segment_total_results: All test results and calculations Authors The modified code was created for a paper by: Marjolein Oostrom, Michael A. Muniak, Rogene Eichler West, Sarah Akers, Paritosh Pande, Moses Obiri, Wei Wang, Kasey Bowyer, Zhuhao Wu, Lisa Bramer, Tianyi Mao, Bobbie Jo Webb-Robertson The work is adapted from Github TrailMap, which was created by Albert Pun and Drew Friedmann Acknowledgments MO, RMEW, SA, MO, LB, BJWR were supported by the Laboratory Directed Research and Development at Pacific Northwest National Laboratory (PNNL), a Department of Energy facility operated by Battelle under contract DE-AC05-76RLO01830. WW, KB, and ZW were supported in part by a NIH/BRAIN Initiative Grant RF1MH128969. MAM and TM were supported by two NIH/BRAIN Initiative Grants R01NS104944, RF1MH120119 and NIH R01NS081071. This research is affiliated with the Pacific northwest bioMedical Innovation Co-laboratory (PMedIC) collaboration between OHSU and PNNL.

Oostrom, Marjolein T↗
DOE OSTI2020

Materials Data on Zn3Fe4(MoO4)6 by Materials Project

Fe4Zn3(MoO4)6 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Mo+5.33+ sites. In the first Mo+5.33+ site, Mo+5.33+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with four FeO6 octahedra and corners with two equivalent ZnO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 22–67°. There is one shorter (1.78 Å) and three longer (1.91 Å) Mo–O bond length. In the second Mo+5.33+ site, Mo+5.33+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with five FeO6 octahedra and a cornercorner with one ZnO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 41–63°. There are a spread of Mo–O bond distances ranging from 1.77–1.83 Å. In the third Mo+5.33+ site, Mo+5.33+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with three FeO6 octahedra and corners with two equivalent ZnO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 24–53°. There are a spread of Mo–O bond distances ranging from 1.76–1.84 Å. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six MoO4 tetrahedra, an edgeedge with one FeO6 octahedra, and an edgeedge with one ZnO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 2.06–2.20 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six MoO4 tetrahedra, an edgeedge with one FeO6 octahedra, and an edgeedge with one ZnO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 2.04–2.30 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are two shorter (2.06 Å) and two longer (2.10 Å) Zn–O bond lengths. In the second Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 trigonal bipyramids that share corners with five MoO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 1.99–2.15 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mo+5.33+, one Fe+2.50+, and one Zn2+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo+5.33+ and one Fe+2.50+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo+5.33+ and one Zn2+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mo+5.33+ and one Zn2+ atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to one Mo+5.33+, one Fe+2.50+, and one Zn2+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mo+5.33+ and two equivalent Fe+2.50+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mo+5.33+, one Fe+2.50+, and one Zn2+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mo+5.33+, one Fe+2.50+, and one Zn2+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mo+5.33+, one Fe+2.50+, and one Zn2+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Mo+5.33+ and two equivalent Fe+2.50+ atoms. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo+5.33+ and one Fe+2.50+ atom. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo+5.33+ and one Fe+2.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag6Mo10O33 by Materials Project

Ag6Mo10O33 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.75–2.30 Å. In the second Mo6+ site, Mo6+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.75–2.51 Å. In the third Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.76–2.45 Å. In the fourth Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.74–2.30 Å. In the fifth Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.74–2.40 Å. There are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Ag–O bond distances ranging from 2.22–2.92 Å. In the second Ag1+ site, Ag1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ag–O bond distances ranging from 2.30–3.03 Å. In the third Ag1+ site, Ag1+ is bonded in a distorted trigonal bipyramidal geometry to five O2- atoms. There are a spread of Ag–O bond distances ranging from 2.34–2.71 Å. There are seventeen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three Mo6+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Mo6+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mo6+ and one Ag1+ atom. In the fourth O2- site, O2- is bonded in a linear geometry to one Mo6+ and one Ag1+ atom. In the fifth O2- site, O2- is bonded to three Mo6+ and one Ag1+ atom to form a mixture of distorted corner and edge-sharing OAgMo3 tetrahedra. In the sixth O2- site, O2- is bonded to three Mo6+ and one Ag1+ atom to form a mixture of distorted corner and edge-sharing OAgMo3 tetrahedra. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Mo6+ and two Ag1+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mo6+ and one Ag1+ atom. In the ninth O2- site, O2- is bonded in a square co-planar geometry to four Mo6+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Mo6+ and one Ag1+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mo6+ and one Ag1+ atom. In the twelfth O2- site, O2- is bonded in a distorted linear geometry to one Mo6+ and one Ag1+ atom. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Mo6+ and one Ag1+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Mo6+ atoms. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and two Ag1+ atoms. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and two Ag1+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted single-bond geometry to two Mo6+ and one Ag1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoH4O5 by Materials Project

MoH4O5 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.73–2.40 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.46 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.45 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.59 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.56 Å) H–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Mo6+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent Mo6+ atoms. In the third O2- site, O2- is bonded in a distorted square co-planar geometry to four H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted square co-planar geometry to four H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Mo6+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Mo6+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Mo6+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Chemical ionization mass spectrometry utilizing benzene cations for measurements of volatile organic compounds and nitric oxide

We evaluate the capability of chemical ionization mass spectrometry (CIMS) using benzene cations as reagent ions (benzene CIMS) for detecting atmospheric trace gases. We characterize the ionization pathways and product ion distributions for 27 analytes spanning diverse chemical classes. To interpret the complex ion chemistry involving two reagent ions (C 6 H$^{+}_{6}$ and (C 6 H 6 )$^{+}_{2}$) and multiple ionization pathways (charge transfer, proton transfer, adduct formation, and hydride abstraction), we introduce a thermodynamics-based framework that classifies analytes into three categories based on their ionization energy (IE), relative to those of benzene monomer (9.24 eV) and dimer (8.69 eV). Each class exhibits distinct ionization mechanisms and product ions. Analytes with IE smaller than 8.69 eV (low IE) undergo charge transfer with both reagent ions; analytes with IE between 8.69 and 9.24 eV (mid IE) undergo charge transfer with C 6 H$^{+}_{6}$ and potential adduct formation with (C 6 H 6 )$^{+}_{2}$; analytes with IE larger than 9.24 eV (high IE) could undergo adduct formation, proton transfer, or hydride abstraction. Analytes within each class also show similar sensitivity, enabling sensitivity estimation for compounds lacking calibration standards. In addition to volatile organic compounds (VOCs), benzene CIMS detects nitric oxide (NO) with a detection limit of 5 pptv for 1 min integration time, exceeding the performance of most commercial NOx analyzers. Field deployments in Chicago and St. Louis demonstrate good agreement with reference NO measurements. Isoprene measurements show good agreement with a co-located gas chromatography–photoionization detector (GC-PID) in St. Louis, but exhibit substantial positive bias in Chicago, likely due to interferences from anthropogenic VOCs in the polluted urban environment. These results highlight the potential of benzene CIMS for concurrent measurements of NO, VOCs, and their oxidation products using a single instrument, while also underscoring challenges in complex atmospheric conditions.

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

Materials Data on K4Co(MoO4)3 by Materials Project

K4Co(MoO4)3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six O2- atoms to form KO6 octahedra that share corners with two equivalent KO6 octahedra and corners with six MoO4 tetrahedra. The corner-sharing octahedral tilt angles are 74°. There are a spread of K–O bond distances ranging from 2.75–2.96 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.66–2.89 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.75–3.42 Å. In the fourth K1+ site, K1+ is bonded to six O2- atoms to form KO6 octahedra that share a cornercorner with one KO6 octahedra, corners with six MoO4 tetrahedra, and an edgeedge with one KO6 octahedra. The corner-sharing octahedral tilt angles are 74°. There are a spread of K–O bond distances ranging from 2.67–2.84 Å. In the fifth K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.80–3.07 Å. There are three inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with three KO6 octahedra and corners with two equivalent CoO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 45–62°. There is two shorter (1.78 Å) and two longer (1.83 Å) Mo–O bond length. In the second Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with four KO6 octahedra and a cornercorner with one CoO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 33–56°. There are a spread of Mo–O bond distances ranging from 1.78–1.83 Å. In the third Mo6+ site, Mo6+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with two KO6 octahedra and corners with two equivalent CoO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Mo–O bond distances ranging from 1.79–1.82 Å. Co2+ is bonded to five O2- atoms to form CoO5 trigonal bipyramids that share corners with five MoO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.96–2.35 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and one Mo6+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three K1+ and one Mo6+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Mo6+, and one Co2+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Mo6+, and one Co2+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Mo6+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three K1+ and one Mo6+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Mo6+, and one Co2+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mo6+ and one Co2+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to three K1+ and one Mo6+ atom. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three K1+ and one Mo6+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one Mo6+, and one Co2+ atom.

36 MATERIALS SCIENCE↗