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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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10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Structure-property relations of oP32-Ge under pressure

The unit-cell parameters, systematic absences, and atomic parameters of the germanium allotrope oP32-Ge show continuous changes up to 6 GPa as shown by single-crystal diffraction analysis. Peak shape and diffuse scattering features remain about unchanged throughout the experiment. Hence, neither the average nor the defect structure behavior offers a structure-property explanation for pressure-induced superconductivity observed at about 2 GPa [1]. Angle dispersive x-ray diffraction reveals a sluggish transformation of oP32-Ge to the Ge-II polymorph, the transition begins around 8 GPa and is complete at 12 GPa, a behavior similar to that of Ge-I. The reconstructive transition was associated with the breakdown of crystals into a powder that was compressed to 32 GPa. Synchrotron infrared absorption measurements up to 8.5 GPa indicate an increase of the band gap of the oP32-Ge prior to its collapse at 8.5 GPa. We suggest that the onset of superconductivity is not associated with a major structural change or that such a change occurs in specific stress and temperature conditions.

Lavina, Barbara↗
DOE OSTI2020

Materials Data on YGe2 by Materials Project

YGe2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Y is bonded to twelve equivalent Ge atoms to form a mixture of distorted edge and face-sharing YGe12 cuboctahedra. There are eight shorter (3.11 Å) and four longer (3.49 Å) Y–Ge bond lengths. Ge is bonded in a 9-coordinate geometry to six equivalent Y and three equivalent Ge atoms. There are two shorter (2.54 Å) and one longer (2.60 Å) Ge–Ge bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3Ge5 by Materials Project

Y3Ge5 crystallizes in the orthorhombic Fdd2 space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded in a 8-coordinate geometry to eight Ge atoms. There are a spread of Y–Ge bond distances ranging from 2.98–3.09 Å. In the second Y site, Y is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Y–Ge bond distances ranging from 2.95–3.50 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to five Y and two equivalent Ge atoms. There are one shorter (2.59 Å) and one longer (2.66 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six Y and three Ge atoms. The Ge–Ge bond length is 2.60 Å. In the third Ge site, Ge is bonded in a 8-coordinate geometry to six Y and two equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3Ge4 by Materials Project

Y3Ge4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded in a 5-coordinate geometry to seven Ge atoms. There are a spread of Y–Ge bond distances ranging from 2.92–3.19 Å. In the second Y site, Y is bonded in a 8-coordinate geometry to eight Ge atoms. There are a spread of Y–Ge bond distances ranging from 3.00–3.11 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to seven Y and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.62 Å. In the second Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Y and four equivalent Ge atoms. All Ge–Ge bond lengths are 2.87 Å. In the third Ge site, Ge is bonded in a 9-coordinate geometry to six Y and three Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y5Ge3 by Materials Project

Y5Ge3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded in a 3-coordinate geometry to five equivalent Ge atoms. There are a spread of Y–Ge bond distances ranging from 2.93–3.47 Å. In the second Y site, Y is bonded in a 6-coordinate geometry to six equivalent Ge atoms. All Y–Ge bond lengths are 3.08 Å. Ge is bonded in a 9-coordinate geometry to nine Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeI2 by Materials Project

GeI2 is trigonal omega-like structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of three GeI2 sheets oriented in the (0, 0, 1) direction. Ge2+ is bonded to six equivalent I1- atoms to form edge-sharing GeI6 octahedra. All Ge–I bond lengths are 3.03 Å. I1- is bonded in a distorted T-shaped geometry to three equivalent Ge2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YGe3 by Materials Project

YGe3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Y is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Y–Ge bond distances ranging from 2.97–3.26 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 7-coordinate geometry to two equivalent Y and five equivalent Ge atoms. There are one shorter (2.51 Å) and four longer (2.83 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded in a 7-coordinate geometry to two equivalent Y and five equivalent Ge atoms. In the third Ge site, Ge is bonded in a 8-coordinate geometry to six equivalent Y and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.57 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeI2 by Materials Project

GeI2 is Molybdenite-like structured and crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one GeI2 sheet oriented in the (0, 0, 1) direction. Ge2+ is bonded to six equivalent I1- atoms to form distorted edge-sharing GeI6 pentagonal pyramids. All Ge–I bond lengths are 3.07 Å. I1- is bonded in a 3-coordinate geometry to three equivalent Ge2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YGe by Materials Project

YGe crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Y is bonded in a 5-coordinate geometry to seven equivalent Ge atoms. There are five shorter (2.98 Å) and two longer (3.23 Å) Y–Ge bond lengths. Ge is bonded in a 5-coordinate geometry to seven equivalent Y and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.70 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeI2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗