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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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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Role of Oxygen on Chemical Segregation in Uncapped Ge 2 Sb 2 Te 5 Thin Films on Silicon Nitride

Germanium antimony telluride has been the most used and studied phase-change material for electronic memory due to its suitable crystallization temperature, amorphous to crystalline resistance contrast, and stability of the amorphous phase. In this paper, the segregation of Ge in a Ge 2 Sb 2 Te 5 film of 30 nm thickness during heating inside the transmission electron microscope was observed and characterized. Furthermore, Ge 2 Sb 2 Te 5 film was deposited using sputtering on a Protochips Fusion holder and left uncapped in atmosphere for about four months. Oxygen incorporated within the film played a significant role in the chemical segregation observed which resulted in amorphous Ge-O island boundaries and Sb and Te rich crystalline domains. Such composition changes can occur when the phase-change material interfaces insulating oxide layers in an integrated device and can significantly impact its electrical and thermal properties.

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

Materials Data on GeO2 by Materials Project

GeO2 is Hydrophilite-like structured and crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Ge4+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing GeO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There is four shorter (1.90 Å) and two longer (1.97 Å) Ge–O bond length. O2- is bonded in a distorted trigonal planar geometry to three equivalent Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeO2 by Materials Project

GeO2 crystallizes in the trigonal P3_121 space group. The structure is three-dimensional. Ge4+ is bonded in a distorted see-saw-like geometry to four equivalent O2- atoms. There are two shorter (2.03 Å) and two longer (2.11 Å) Ge–O bond lengths. O2- is bonded in a 3-coordinate geometry to two equivalent Ge4+ and one O2- atom. The O–O bond length is 1.54 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeO2 by Materials Project

GeO2 crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Ge4+ is bonded to six equivalent O2- atoms to form corner-sharing GeO6 octahedra. The corner-sharing octahedral tilt angles are 60°. All Ge–O bond lengths are 1.95 Å. O2- is bonded in a trigonal planar geometry to three equivalent Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeO2 by Materials Project

GeO2 is Rutile structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Ge4+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing GeO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There is four shorter (1.90 Å) and two longer (1.95 Å) Ge–O bond length. O2- is bonded in a distorted trigonal planar geometry to three equivalent Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeO2 by Materials Project

GeO2 is quartz (alpha) structured and crystallizes in the trigonal P3_121 space group. The structure is three-dimensional. Ge4+ is bonded to four equivalent O2- atoms to form corner-sharing GeO4 tetrahedra. There is two shorter (1.76 Å) and two longer (1.77 Å) Ge–O bond length. O2- is bonded in a bent 120 degrees geometry to two equivalent Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeO2 by Materials Project

GeO2 is low (alpha) Cristobalite structured and crystallizes in the tetragonal P4_12_12 space group. The structure is three-dimensional. Ge4+ is bonded to four equivalent O2- atoms to form corner-sharing GeO4 tetrahedra. There is two shorter (1.76 Å) and two longer (1.77 Å) Ge–O bond length. O2- is bonded in a bent 120 degrees geometry to two equivalent Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ge2O3 by Materials Project

Ge2O3 is (Cubic) Perovskite-derived structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. there are two inequivalent Ge3+ sites. In the first Ge3+ site, Ge3+ is bonded to twelve equivalent O2- atoms to form GeO12 cuboctahedra that share corners with twelve equivalent GeO12 cuboctahedra, faces with six equivalent GeO12 cuboctahedra, and faces with eight equivalent GeO6 octahedra. All Ge–O bond lengths are 2.67 Å. In the second Ge3+ site, Ge3+ is bonded to six equivalent O2- atoms to form GeO6 octahedra that share corners with six equivalent GeO6 octahedra and faces with eight equivalent GeO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All Ge–O bond lengths are 1.89 Å. O2- is bonded in a linear geometry to six Ge3+ atoms.

36 MATERIALS SCIENCE↗