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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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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Neutral Silicon-Vacancy Centers in Diamond via Photoactivated Itinerant Carriers

Neutral silicon-vacancy (Si-V 0 ) centers in diamond are promising candidates for quantum network applications because of their exceptional optical properties and spin coherence. However, the stabilization of Si-V 0 centers requires careful Fermi-level engineering of the diamond host material, making further technological development challenging. Here, we show that Si-V 0 centers can be efficiently stabilized by photoactivated itinerant carriers. Even in this nonequilibrium configuration, the resulting Si-V 0 centers are stable enough to allow for resonant optical excitation and optically detected magnetic resonance. Furthermore, our results pave the way for on-demand generation of Si-V 0 centers as well as other emerging quantum defects in diamond.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2021

Phase transformations, microstructural refinement and defect evolution mechanisms in Al-Si alloys under non-hydrostatic diamond anvil cell compression

Non-hydrostatic compression of materials using a diamond anvil cell (DAC) can transform equilibrium microstructure of an alloy to novel, potentially metastable states. In this study, in situ synchrotron X-ray diffraction (XRD) during compression up to 24 GPa and subsequent ex situ, high resolution analytical electron microscopy (AEM) after decompression of an Al-Si alloy provided insight into the crystallographic changes during the compression as well as microstructural refinement, and defect structures caused by such a high pressure compression-decompression process. Pressure resolved in-situ synchrotron XRD was used to detail the phase transformation pathway of the eutectic Si phase in Al-Si alloy, from Si-I → Si-XI → Si-V during compression, and a final transformation predominantly to Si-III after decompression. Using scanning and transmission electron microscopy (S/TEM), site specific analysis of the alloy immediately underneath the anvil contact surface demonstrated a highly complex microstructure. A narrow region of thick amorphous Al oxide interspersed with nanocrystalline grains was found at the top surface. Underneath this Al oxide, while the majority the eutectic Si was transformed into highly-deformed, polycrystalline (PC) Si-III, a complex intermediate layer was discovered at the interface between Al and Si, comprised of a small fraction of Al nanocrystals and a majority of nanocrystalline Si-I. This combination of pressure resolved in-situ synchrotron XRD coupled with subsequent high resolution, electron microscopy resolved the phase transformation as well as non-equilibrium microstructures in a metallic alloy induced by a non-hydrostatic high pressure compression followed by decompression.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on VSi2 by Materials Project

VSi2 is Titanium Disilicide-like structured and crystallizes in the hexagonal P6_222 space group. The structure is three-dimensional. V is bonded in a distorted q6 geometry to ten equivalent Si atoms. There are a spread of V–Si bond distances ranging from 2.51–2.67 Å. Si is bonded in a 10-coordinate geometry to five equivalent V and five equivalent Si atoms. There are a spread of Si–Si bond distances ranging from 2.48–2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on VSi2 by Materials Project

VSi2 is Titanium Disilicide-like structured and crystallizes in the hexagonal P6_422 space group. The structure is three-dimensional. V is bonded in a distorted q6 geometry to ten equivalent Si atoms. There are a spread of V–Si bond distances ranging from 2.51–2.67 Å. Si is bonded in a 10-coordinate geometry to five equivalent V and five equivalent Si atoms. There are a spread of Si–Si bond distances ranging from 2.48–2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V3Si by Materials Project

V3Si crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. V is bonded in a 6-coordinate geometry to two equivalent V and four equivalent Si atoms. Both V–V bond lengths are 2.35 Å. All V–Si bond lengths are 2.63 Å. Si is bonded to twelve equivalent V atoms to form a mixture of face and edge-sharing SiV12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V5Si3 by Materials Project

V5Si3 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent V+2.40+ sites. In the first V+2.40+ site, V+2.40+ is bonded to six Si4- atoms to form a mixture of distorted face, edge, and corner-sharing VSi6 pentagonal pyramids. There are a spread of V–Si bond distances ranging from 2.49–2.72 Å. In the second V+2.40+ site, V+2.40+ is bonded in a distorted hexagonal planar geometry to two equivalent V+2.40+ and four equivalent Si4- atoms. Both V–V bond lengths are 2.36 Å. All V–Si bond lengths are 2.51 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 10-coordinate geometry to ten V+2.40+ atoms. In the second Si4- site, Si4- is bonded in a 10-coordinate geometry to eight equivalent V+2.40+ and two equivalent Si4- atoms. Both Si–Si bond lengths are 2.36 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V5Si3 by Materials Project

V5Si3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent V+2.40+ sites. In the first V+2.40+ site, V+2.40+ is bonded to five equivalent Si4- atoms to form a mixture of distorted corner and edge-sharing VSi5 trigonal bipyramids. There are a spread of V–Si bond distances ranging from 2.46–2.65 Å. In the second V+2.40+ site, V+2.40+ is bonded in a 6-coordinate geometry to two equivalent V+2.40+ and six equivalent Si4- atoms. Both V–V bond lengths are 2.42 Å. All V–Si bond lengths are 2.50 Å. Si4- is bonded in a 9-coordinate geometry to nine V+2.40+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V3Si by Materials Project

V3Si is High-temperature superconductor structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. V is bonded to four equivalent V and two equivalent Si atoms to form VV4Si2 octahedra that share corners with six equivalent VV4Si2 octahedra, edges with four equivalent SiV6 octahedra, and edges with eight equivalent VV4Si2 octahedra. The corner-sharing octahedral tilt angles are 0°. All V–V bond lengths are 2.46 Å. Both V–Si bond lengths are 2.46 Å. Si is bonded to six equivalent V atoms to form SiV6 octahedra that share corners with six equivalent SiV6 octahedra and edges with twelve equivalent VV4Si2 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V6Si5 by Materials Project

V6Si5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. there are three inequivalent V2+ sites. In the first V2+ site, V2+ is bonded in a 8-coordinate geometry to two equivalent V2+ and six Si+2.40- atoms. Both V–V bond lengths are 2.42 Å. There are a spread of V–Si bond distances ranging from 2.44–2.56 Å. In the second V2+ site, V2+ is bonded to seven Si+2.40- atoms to form a mixture of corner, edge, and face-sharing VSi7 pentagonal bipyramids. There are a spread of V–Si bond distances ranging from 2.55–2.75 Å. In the third V2+ site, V2+ is bonded to seven Si+2.40- atoms to form a mixture of distorted corner, edge, and face-sharing VSi7 pentagonal bipyramids. There are a spread of V–Si bond distances ranging from 2.37–2.69 Å. There are three inequivalent Si+2.40- sites. In the first Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to eight V2+ and two equivalent Si+2.40- atoms. Both Si–Si bond lengths are 2.42 Å. In the second Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to nine V2+ atoms. In the third Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to seven V2+ and three equivalent Si+2.40- atoms. There are one shorter (2.44 Å) and two longer (2.77 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗