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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Mo2CN by Materials Project

Mo2N(C) is Tungsten Carbide-derived structured and crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. there are two inequivalent Mo+3.50+ sites. In the first Mo+3.50+ site, Mo+3.50+ is bonded to four equivalent C4- and two equivalent N3- atoms to form a mixture of distorted edge, face, and corner-sharing MoC4N2 pentagonal pyramids. All Mo–C bond lengths are 2.20 Å. Both Mo–N bond lengths are 2.20 Å. In the second Mo+3.50+ site, Mo+3.50+ is bonded to two equivalent C4- and four equivalent N3- atoms to form distorted MoC2N4 pentagonal pyramids that share corners with twelve MoC4N2 pentagonal pyramids, edges with six MoC4N2 pentagonal pyramids, and faces with two equivalent MoC2N4 pentagonal pyramids. Both Mo–C bond lengths are 2.19 Å. All Mo–N bond lengths are 2.20 Å. C4- is bonded to six Mo+3.50+ atoms to form distorted CMo6 pentagonal pyramids that share corners with four equivalent CMo6 pentagonal pyramids, corners with eight equivalent NMo6 pentagonal pyramids, edges with two equivalent CMo6 pentagonal pyramids, edges with four equivalent NMo6 pentagonal pyramids, and faces with two equivalent CMo6 pentagonal pyramids. N3- is bonded to six Mo+3.50+ atoms to form distorted NMo6 pentagonal pyramids that share corners with four equivalent NMo6 pentagonal pyramids, corners with eight equivalent CMo6 pentagonal pyramids, edges with two equivalent NMo6 pentagonal pyramids, edges with four equivalent CMo6 pentagonal pyramids, and faces with two equivalent NMo6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgMo3 by Materials Project

MgMo3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg is bonded in a distorted body-centered cubic geometry to fourteen Mo atoms. There are eight shorter (2.76 Å) and six longer (3.19 Å) Mg–Mo bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded to four equivalent Mg and four equivalent Mo atoms to form a mixture of distorted edge, face, and corner-sharing MoMg4Mo4 tetrahedra. All Mo–Mo bond lengths are 2.76 Å. In the second Mo site, Mo is bonded in a 8-coordinate geometry to six equivalent Mg and eight equivalent Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on InMo12PbS16 by Materials Project

Mo12InPbS16 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are two inequivalent Mo+2.42+ sites. In the first Mo+2.42+ site, Mo+2.42+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.56 Å. In the second Mo+2.42+ site, Mo+2.42+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.56 Å. In1+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are two shorter (2.80 Å) and six longer (3.15 Å) In–S bond lengths. Pb2+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are two shorter (2.81 Å) and six longer (3.15 Å) Pb–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to three equivalent Mo+2.42+ and one Pb2+ atom. In the second S2- site, S2- is bonded in a 4-coordinate geometry to three equivalent Mo+2.42+ and one In1+ atom. In the third S2- site, S2- is bonded in a 5-coordinate geometry to four Mo+2.42+ and one In1+ atom. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to four Mo+2.42+ and one Pb2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Yb3Mo by Materials Project

Yb3Mo is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are three inequivalent Yb sites. In the first Yb site, Yb is bonded to four Yb and four Mo atoms to form a mixture of distorted face, edge, and corner-sharing YbYb4Mo4 tetrahedra. All Yb–Yb bond lengths are 3.27 Å. All Yb–Mo bond lengths are 3.27 Å. In the second Yb site, Yb is bonded in a 10-coordinate geometry to eight equivalent Yb and six Mo atoms. There are two shorter (3.75 Å) and four longer (3.80 Å) Yb–Mo bond lengths. In the third Yb site, Yb is bonded in a 10-coordinate geometry to eight equivalent Yb and six Mo atoms. There are two shorter (3.75 Å) and four longer (3.80 Å) Yb–Mo bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a distorted body-centered cubic geometry to fourteen Yb atoms. In the second Mo site, Mo is bonded in a distorted body-centered cubic geometry to fourteen Yb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Identification of Active Metal Carbide and Nitride Catalytic Facets for Hydrodeoxygenation Reactions

The catalytic hydrodeoxygenation (HDO) reaction is of considerable interest for biomass conversion to valuable chemicals and fuels, where one of the critical bottlenecks is the lack of cost-effective and efficient catalysts. To discover cost-efficient catalysts for the HDO reaction, we employed a density functional theory-based hierarchical catalyst design strategy based on catalytic descriptors, reaction energy profiles, and microkinetic modeling (MKM). We focused on the carbide and nitride catalyst space, for which we calculated 121 catalyst surfaces of Mo 2 C, MoC, Mo 2 N, W 2 C, NbC, VC, VN, and NbN catalysts. Based on the computed surface energies, reaction energies of oxygen removal, carbon binding strength, and the surface area of nanoparticles, the likely active facets are the Mo 2 C(111), MoC(011), VN(100), Mo 2 N(001), Mo 2 N(011), and Mo 2 N(100) surfaces. Further, detailed energy profiles were obtained, and MKM was performed for a model reaction (glycolaldehyde + 2H 2 . ethylene + 2H 2 O) on the Mo 2 C(111), VN(100), and MoC(100) surfaces. Based on the computed volcano map obtained from MKM, the predicted active facets for this HDO reaction are the Mo 2 C(111), MoC(011), VN(011), Mo 2 N(001), Mo 2 N(011), and Mo 2 N(100) surfaces. Additionally, none of the carbide and nitride catalyst surfaces are located in the optimal catalytic activity part. Therefore, it is essential to modify the catalyst via adding dopants or alloying to improve the catalytic activity. Catalytic modifications that can destabilize the surface adsorption of O*/H 2 O* and decrease the energy barriers of O-H bond formation are recommended to facilitate the HDO on the carbide and nitride catalysts. These a priori investigations provide guidelines for future low-cost HDO catalyst development.

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

Small Punch Testing of Molybdenum-99 Targets

Northstar Medical Radioisotopes is developing an accelerator-based method to produce 99 Mo, which is a parent isotope of the commonly used 99m Tc medical isotope. The Mo targets being designed for the accelerator will be produced from enriched 100 Mo, also known as aMo . Pressed and sintered powder feedstock is used to fabricate aMo targets, producing 29 mm disk-shaped targets. The targets are subjected to 1–6 days in line of an electron beam with subsequent dissolution of the disk to retain the 99 Mo, which decays to 99m Tc at radio-pharmacies. The press and sinter method is advantageous because the inherent porosity produced by this method enables increased surface area and therefore increased flow of dissolution media, decreasing the dissolution time and reducing the need for a highly acidic media. Although porosity aids in dissolution, it reduces the mechanical strength and ductility. Targets require good mechanical integrity when subjected to the conditions in the accelerator. Therefore, Northstar is seeking methods to rapidly test disk samples after fabrication to assure mechanical performance metrics are achieved. This report details the design and testing of a small punch test (SPT) that accommodates the 29 mm disk. Initial data were used to relate the SPT data to tensile properties, such as the yield strength (YS), ultimate tensile strength (UTS), and total elongation to failure. Although the SPT has been established as a somewhat reliable method for testing metallic materials, few studies have applied the SPT to refractory materials such as Mo. Based on tensile testing performed at Oak Ridge National Laboratory on different Mo samples, correlation between the Mo tensile and SPT properties could be performed, establishing a standard calibration that could be applied to other Mo samples. To test the efficacy of the SPT with Mo, multiple different disk batches were fabricated under different conditions (e.g., pressure, lubricant) with commercially available pure Mo powder. Generally, only a UTS could be well defined because the press and sinter disks failed under brittle fracture, making it difficult to determine the YS and elongation. Compared with disks fabricated with aMo powder, the aMo samples underperformed their pure nat Mo counterparts. This report summarizes the current status of the SPT, but further evaluation is needed before it can be applied as a reliable quality assurance tool.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

A New Process for Small-Batch Purification of the Medical Isotope Molybdenum-99: Non-Technical Overview

The U.S. medical community depends on a reliable supply of the radioisotope molybdenum-99 (Mo-99) for nuclear medical diagnostic procedures. Mo-99's decay product, technetium-99m (Tc-99m), is used in over 40,000 medical procedures in the United States each day to diagnose heart disease and cancer, to study organ structure and function, and to perform other important medical applications. For example, patients undergoing a common procedure—the cardiac “stress test”—likely have benefited from Tc-99m. Historically, Mo-99 was primarily produced through the fission of uranium-235, in the form of highly enriched uranium (HEU) targets irradiated in research and test reactors. HEU is a proliferation-sensitive material that, if diverted or stolen, could be used as a component of a nuclear weapon. NNSA’s Office of Material Management and Minimization (M3) manages the Molybdenum-99 (Mo-99) Program as part of its mission to minimize the use of HEU in civilian applications. The Mo-99 Program assists global Mo-99 production facilities in converting to non-HEU processes and supports the establishment of domestic supplies of Mo-99 without the use of proliferation-sensitive HEU. As part of this program, M3 funds U.S. national laboratories to provide non-proprietary technical support to U.S. companies working to establish non-HEU-based Mo-99 production capabilities. The results of this research are published on OSTI.gov for the benefit of the Mo-99 community and the public. However, it can be difficult for readers without a scientific background to understand and interpret these publications. In order to increase public understanding of the work being done in M3’s Mo-99 Program, this paper aims to provide an overview of a key, recent national laboratory technical publication in terms that can be understood by readers without a technical background. To accomplish this, the paper first explains key scientific concepts—primarily related to chemistry—that provide a foundation for understanding research in this area. This includes chromatography, absorption vs. adsorption, dissolution and precipitation, and liquid-liquid extraction. Drawing on these concepts, the paper then provides an explanation for non-technical audiences of the Argonne National Laboratory publication entitled Recovery of High Specific Activity Molybdenum-99 from Accelerator-Induced Fission on Low-Enriched Uranium for Technetium-99m Generators (Brown, M.A. et al., 2021) and related article Separation and Purification of Mo-99 Produced from Natural U3O8 Targets via Photo-Fission (Brown, M.A. et al., 2021).

Stamler, Bradley↗
DOE OSTI2024

Bioavailability of molybdenite to support nitrogen fixation on early Earth by an anoxygenic phototroph

Biological nitrogen fixation, which converts atmospheric dinitrogen to ammonia, is catalyzed mostly by Mo-nitrogenase and is a primary contributor to bioavailable nitrogen on early Earth. Mo-nitrogenase is believed to have evolved during the Archean, despite the extremely low concentration of dissolved Mo. However, it remains unclear whether Mo minerals could serve as a source of Mo to support the prevalence of Mo-nitrogenase on early Earth. Here, in this study, we investigated the bioavailability of molybdenite by incubating it with a metabolically ancient anoxygenic phototroph (Rhodopseudomonas palustris) under anoxic conditions. In the laboratory, R. palustris utilized molybdenum from molybdenite as a cofactor for nitrogen fixation. This bacterium extracted Mo from molybdenite by secreting molybdophores rhodopetrobactin A and B and by expressing Mo transport proteins. Surface-sensitive techniques demonstrated significant changes in surface chemistry of molybdenite after its interaction with cells. These findings provide novel explanations for the prevalence of Mo-nitrogenase on early Earth, with significant implications for nitrogen fixation in modern Mo-deficient environments.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Materials Data on Rb2Mo9S11 by Materials Project

Rb2Mo9S11 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Rb1+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Rb–S bond distances ranging from 3.07–3.53 Å. There are two inequivalent Mo+2.22+ sites. In the first Mo+2.22+ site, Mo+2.22+ is bonded to five S2- atoms to form a mixture of corner and edge-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.63 Å. In the second Mo+2.22+ site, Mo+2.22+ is bonded in a see-saw-like geometry to four S2- atoms. There are two shorter (2.46 Å) and two longer (2.47 Å) Mo–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent Rb1+ and four Mo+2.22+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to one Rb1+ and four Mo+2.22+ atoms. In the third S2- site, S2- is bonded in a 4-coordinate geometry to one Rb1+ and three equivalent Mo+2.22+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbMo6Se7 by Materials Project

RbMo6Se7 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Rb1+ is bonded in a 10-coordinate geometry to ten Se2- atoms. There are a spread of Rb–Se bond distances ranging from 3.62–3.91 Å. There are two inequivalent Mo+2.17+ sites. In the first Mo+2.17+ site, Mo+2.17+ is bonded in a see-saw-like geometry to four Se2- atoms. There are a spread of Mo–Se bond distances ranging from 2.59–2.72 Å. In the second Mo+2.17+ site, Mo+2.17+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.70 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to one Rb1+ and four Mo+2.17+ atoms. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to one Rb1+ and three equivalent Mo+2.17+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent Rb1+ and four Mo+2.17+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsTe7Mo6 by Materials Project

CsMo6Te7 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Cs1+ is bonded in a 10-coordinate geometry to ten Te2- atoms. There are a spread of Cs–Te bond distances ranging from 3.87–4.20 Å. There are two inequivalent Mo+2.17+ sites. In the first Mo+2.17+ site, Mo+2.17+ is bonded to five Te2- atoms to form a mixture of corner and edge-sharing MoTe5 square pyramids. There are a spread of Mo–Te bond distances ranging from 2.74–2.92 Å. In the second Mo+2.17+ site, Mo+2.17+ is bonded in a see-saw-like geometry to four Te2- atoms. There are a spread of Mo–Te bond distances ranging from 2.79–2.88 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 5-coordinate geometry to one Cs1+ and four Mo+2.17+ atoms. In the second Te2- site, Te2- is bonded in a 6-coordinate geometry to two equivalent Cs1+ and four Mo+2.17+ atoms. In the third Te2- site, Te2- is bonded in a 7-coordinate geometry to one Cs1+ and three equivalent Mo+2.17+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ni2Mo4C by Materials Project

Mo4Ni2C crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. there are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a 2-coordinate geometry to four equivalent Ni and two equivalent C atoms. There are two shorter (2.69 Å) and two longer (2.89 Å) Mo–Ni bond lengths. Both Mo–C bond lengths are 2.13 Å. In the second Mo site, Mo is bonded in a 6-coordinate geometry to six equivalent Ni atoms. All Mo–Ni bond lengths are 2.45 Å. Ni is bonded in a 12-coordinate geometry to nine Mo and three equivalent Ni atoms. All Ni–Ni bond lengths are 2.65 Å. C is bonded to six equivalent Mo atoms to form corner-sharing CMo6 octahedra. The corner-sharing octahedral tilt angles are 40°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2Mo9S11 by Materials Project

K2Mo9S11 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. K1+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of K–S bond distances ranging from 2.99–3.46 Å. There are two inequivalent Mo+2.22+ sites. In the first Mo+2.22+ site, Mo+2.22+ is bonded to five S2- atoms to form a mixture of corner and edge-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.63 Å. In the second Mo+2.22+ site, Mo+2.22+ is bonded in a see-saw-like geometry to four S2- atoms. There are two shorter (2.46 Å) and two longer (2.48 Å) Mo–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent K1+ and four Mo+2.22+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to one K1+ and four Mo+2.22+ atoms. In the third S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three equivalent Mo+2.22+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co2Mo4C by Materials Project

Mo4Co2C crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. there are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a 6-coordinate geometry to six equivalent Co atoms. All Mo–Co bond lengths are 2.43 Å. In the second Mo site, Mo is bonded in a 2-coordinate geometry to four equivalent Co and two equivalent C atoms. There are two shorter (2.71 Å) and two longer (2.91 Å) Mo–Co bond lengths. Both Mo–C bond lengths are 2.12 Å. Co is bonded in a 12-coordinate geometry to nine Mo and three equivalent Co atoms. All Co–Co bond lengths are 2.60 Å. C is bonded to six equivalent Mo atoms to form corner-sharing CMo6 octahedra. The corner-sharing octahedral tilt angles are 39°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo2As3 by Materials Project

Mo2As3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Mo+4.50+ sites. In the first Mo+4.50+ site, Mo+4.50+ is bonded to six As3- atoms to form a mixture of edge, face, and corner-sharing MoAs6 octahedra. The corner-sharing octahedra tilt angles range from 44–53°. There are a spread of Mo–As bond distances ranging from 2.53–2.61 Å. In the second Mo+4.50+ site, Mo+4.50+ is bonded to six As3- atoms to form a mixture of distorted edge, face, and corner-sharing MoAs6 octahedra. The corner-sharing octahedra tilt angles range from 44–53°. There are a spread of Mo–As bond distances ranging from 2.55–2.63 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded in a 5-coordinate geometry to four Mo+4.50+ and one As3- atom. The As–As bond length is 3.01 Å. In the second As3- site, As3- is bonded in a 4-coordinate geometry to four Mo+4.50+ atoms. In the third As3- site, As3- is bonded in a 5-coordinate geometry to four Mo+4.50+ and one As3- atom. The As–As bond length is 2.50 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(Mo6S7)2 by Materials Project

K(Mo6S7)2 crystallizes in the trigonal P-31c space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are two shorter (3.00 Å) and six longer (3.38 Å) K–S bond lengths. There are two inequivalent Mo+2.25+ sites. In the first Mo+2.25+ site, Mo+2.25+ is bonded in a see-saw-like geometry to four S2- atoms. There are a spread of Mo–S bond distances ranging from 2.44–2.57 Å. In the second Mo+2.25+ site, Mo+2.25+ is bonded to five S2- atoms to form a mixture of edge and corner-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.40–2.64 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three equivalent Mo+2.25+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to one K1+ and four Mo+2.25+ atoms. In the third S2- site, S2- is bonded in a 4-coordinate geometry to four Mo+2.25+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsMo6Se7 by Materials Project

CsMo6Se7 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Cs1+ is bonded in a 10-coordinate geometry to ten Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.69–3.90 Å. There are two inequivalent Mo+2.17+ sites. In the first Mo+2.17+ site, Mo+2.17+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.55–2.70 Å. In the second Mo+2.17+ site, Mo+2.17+ is bonded in a see-saw-like geometry to four Se2- atoms. There are a spread of Mo–Se bond distances ranging from 2.60–2.71 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent Cs1+ and four Mo+2.17+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to one Cs1+ and four Mo+2.17+ atoms. In the third Se2- site, Se2- is bonded in a 7-coordinate geometry to one Cs1+ and three equivalent Mo+2.17+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo9Se11 by Materials Project

Mo9Se11 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. there are two inequivalent Mo+2.44+ sites. In the first Mo+2.44+ site, Mo+2.44+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.73 Å. In the second Mo+2.44+ site, Mo+2.44+ is bonded in a see-saw-like geometry to four Se2- atoms. There are three shorter (2.57 Å) and one longer (2.60 Å) Mo–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 10-coordinate geometry to three equivalent Mo+2.44+ atoms. In the second Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.44+ atoms. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to four Mo+2.44+ atoms.

36 MATERIALS SCIENCE↗