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7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on UF3 by Materials Project

UF3 crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. U3+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of U–F bond distances ranging from 2.41–2.83 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 2-coordinate geometry to four equivalent U3+ atoms. In the second F1- site, F1- is bonded in a distorted trigonal planar geometry to three equivalent U3+ atoms. In the third F1- site, F1- is bonded in a trigonal planar geometry to three equivalent U3+ atoms. In the fourth F1- site, F1- is bonded in a distorted trigonal planar geometry to three equivalent U3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UF3 by Materials Project

UF3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U3+ is bonded to twelve F1- atoms to form a mixture of corner, edge, and face-sharing UF12 cuboctahedra. There are eight shorter (2.55 Å) and four longer (2.63 Å) U–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to four equivalent U3+ atoms. In the second F1- site, F1- is bonded in a distorted square co-planar geometry to four equivalent U3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UF3 by Materials Project

UF3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. U3+ is bonded in a distorted body-centered cubic geometry to fourteen F1- atoms. There are eight shorter (2.52 Å) and six longer (2.91 Å) U–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to four equivalent U3+ and four equivalent F1- atoms to form a mixture of corner, edge, and face-sharing FU4F4 tetrahedra. All F–F bond lengths are 2.52 Å. In the second F1- site, F1- is bonded in a 6-coordinate geometry to six equivalent U3+ and eight equivalent F1- atoms.

36 MATERIALS SCIENCE↗
NASA NTRS2000

A Technology Demonstration Experiment for Laser Cooled Atomic Clocks in Space

We have been developing a laser-cooling apparatus for flight on the International Space Station (ISS), with the intention of demonstrating linewidths on the cesium clock transition narrower than can be realized on the ground. GLACE (the Glovebox Laser- cooled Atomic Clock Experiment) is scheduled for launch on Utilization Flight 3 (UF3) in 2002, and will be mounted in one of the ISS Glovebox platforms for an anticipated 2-3 week run. Separate flight definition projects funded at NIST and Yale by the Micro- gravity Research Division of NASA as a part of its Laser Cooling and Atomic Physics (LCAP) program will follow GLACE. Core technologies for these and other LCAP missions are being developed at JPL, with the current emphasis on developing components such as the laser and optics subsystem, and non-magnetic vacuum-compatible mechanical shutters. Significant technical challenges in developing a space qualifiable laser cooling apparatus include reducing the volume, mass, and power requirements, while increasing the ruggedness and reliability in order to both withstand typical launch conditions and achieve several months of unattended operation. This work was performed at the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

Klipstein, W. M.↗
NASA NTRSDate not supplied

Hierarchical screening for Li-based solid electrolytes using fast, interpretable machine-learned potentials

Li-based solid-state electrolyte materials enable safer, all-solid-state batteries but the computational search for candidates with favorable stability and Li-ion conductivity is challenging due to the size of the search space and the cost of evaluating transport properties with ab initio methods. The prohibitive cost of high-throughput screening with DFT has lead to the development of surrogate models using geometric analysis, empirical potentials, and descriptors for ionic transport. Here, I will discuss a hierarchical screening approach for identifying promising materials using a combination of density functional theory, bond-valence methods, and machine learning potentials generated with the Ultra-Fast Force Fields (UF3) framework. We show how the inexpensive bond-valence method can be used to guide the generation of training samples for machine learning, in addition to filtering candidates. Finally, we apply the hierarchical workflow to screen for ionic conductivity across a database of Li-containing compounds.

Materials discovery↗
NASA NTRSDate not supplied

Hierarchical Screening for Li-Based Solid Electrolytes Using Fast, Interpretable Machine-Learned Potentials

Li-based solid-state electrolyte materials enable safer, all-solid-state batteries but the computational search for candidates with favorable stability and Li-ion conductivity is challenging due to the size of the search space and the cost of evaluating transport properties with ab initio methods. The prohibitive cost of high-throughput screening with DFT has lead to the development of surrogate models using geometric analysis, empirical potentials, and descriptors for ionic transport. Here, I will discuss a hierarchical screening approach for identifying promising materials using a combination of density functional theory, bond-valence methods, and machine learning potentials generated with the Ultra-Fast Force Fields (UF3) framework. We show how the inexpensive bond-valence method can be used to guide the generation of training samples for machine learning, in addition to filtering candidates.

Materials discovery↗