Search NASA⌕ Search

SEARCH · Search NASA

Results for “HfMg”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Processing, structure, and thermal properties of ZrW 2 O 8 , HfW 2 O 8 , HfMgW 3 O 12 , Al(HfMg) 0.5 W 3 O 12 , and Al 0.5 Sc 1.5 W 3 O 12 negative and zero thermal expansion coefficient ceramics

Negative and zero coefficient of thermal expansion (CTE) materials are of interest for developing polymer composites in electronic circuits that match the expansion of Si and in zero CTE supports for optical components, e.g., mirrors. In this work, the processing challenges and stability of ZrW 2 O 8 , HfW 2 O 8 , HfMgW 3 O 12 , Al(HfMg) 0.5 W 3 O 12 , and Al 0.5 Sc 1.5 W 3 O 12 negative and zero thermal expansion coefficient ceramics are discussed. Al 0.5 Sc 1.5 W 3 O 12 is demonstrated to be a relatively simple oxide to fabricate in large quantity and is shown to exhibit single phase up to 1300 °C in air and inert N 2 environments. The negative and zero CTE behavior was confirmed with dilatometry. Thermal conductivity and heat capacity were reported for the first time for HfMgW 3 O 12 and Al 0.5 Sc 1.5 W 3 O 12 and thermal conductivity was found to be very low (~0.5 W/mK). Grüneisen parameter is also estimated. Methods for integration of Al 0.5 Sc 1.5 W 3 O 12 with other materials was examined and embedding 50 vol% of the ceramic powder in flexible epoxy was demonstrated with a commercial vendor.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfMg by Materials Project

Mg(Hf) is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to four equivalent Hf atoms to form corner-sharing MgHf4 tetrahedra. All Mg–Hf bond lengths are 2.84 Å. Hf is bonded to four equivalent Mg atoms to form corner-sharing HfMg4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfMg by Materials Project

Mg(Hf) is beta-prime cadmium gold structured and crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. Mg is bonded to four equivalent Mg and eight equivalent Hf atoms to form MgHf8Mg4 cuboctahedra that share corners with eight equivalent HfHf4Mg8 cuboctahedra, corners with ten equivalent MgHf8Mg4 cuboctahedra, edges with six equivalent MgHf8Mg4 cuboctahedra, edges with twelve equivalent HfHf4Mg8 cuboctahedra, faces with eight equivalent HfHf4Mg8 cuboctahedra, and faces with twelve equivalent MgHf8Mg4 cuboctahedra. There are two shorter (3.16 Å) and two longer (3.22 Å) Mg–Mg bond lengths. There are a spread of Mg–Hf bond distances ranging from 3.08–3.12 Å. Hf is bonded to eight equivalent Mg and four equivalent Hf atoms to form HfHf4Mg8 cuboctahedra that share corners with eight equivalent MgHf8Mg4 cuboctahedra, corners with ten equivalent HfHf4Mg8 cuboctahedra, edges with six equivalent HfHf4Mg8 cuboctahedra, edges with twelve equivalent MgHf8Mg4 cuboctahedra, faces with eight equivalent MgHf8Mg4 cuboctahedra, and faces with twelve equivalent HfHf4Mg8 cuboctahedra. There are two shorter (3.16 Å) and two longer (3.22 Å) Hf–Hf bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfMg by Materials Project

Mg(Hf) is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg is bonded to six equivalent Hf atoms to form a mixture of edge and corner-sharing MgHf6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–Hf bond lengths are 2.86 Å. Hf is bonded to six equivalent Mg atoms to form a mixture of edge and corner-sharing HfMg6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfMg by Materials Project

Mg(Hf) is Copper-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six equivalent Mg and six Hf atoms to form MgHf6Mg6 cuboctahedra that share corners with twelve MgHf6Mg6 cuboctahedra, edges with twelve MgHf6Mg6 cuboctahedra, edges with twelve HfHf6Mg6 cuboctahedra, faces with six equivalent MgHf6Mg6 cuboctahedra, and faces with twelve HfHf6Mg6 cuboctahedra. All Mg–Mg bond lengths are 3.05 Å. All Mg–Hf bond lengths are 3.26 Å. In the second Mg site, Mg is bonded to ten equivalent Mg and six Hf atoms to form MgHf6Mg10 cuboctahedra that share corners with ten HfHf6Mg6 cuboctahedra, corners with twelve MgHf6Mg6 cuboctahedra, edges with eight HfHf6Mg6 cuboctahedra, edges with sixteen MgHf6Mg6 cuboctahedra, faces with sixteen equivalent MgHf6Mg10 cuboctahedra, and faces with eighteen HfHf6Mg6 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.05–6.09 Å. All Mg–Hf bond lengths are 3.26 Å. There are three inequivalent Hf sites. In the first Hf site, Hf is bonded to six equivalent Mg and six equivalent Hf atoms to form HfHf6Mg6 cuboctahedra that share corners with twelve HfHf6Mg6 cuboctahedra, edges with twelve equivalent MgHf6Mg6 cuboctahedra, edges with twelve HfHf6Mg6 cuboctahedra, faces with six equivalent HfHf6Mg6 cuboctahedra, and faces with twelve equivalent MgHf6Mg6 cuboctahedra. All Hf–Hf bond lengths are 3.05 Å. In the second Hf site, Hf is bonded to six Mg and six equivalent Hf atoms to form HfHf6Mg6 cuboctahedra that share corners with five equivalent MgHf6Mg10 cuboctahedra, corners with twelve HfHf6Mg6 cuboctahedra, edges with ten MgHf6Mg6 cuboctahedra, edges with twelve HfHf6Mg6 cuboctahedra, faces with six equivalent HfHf6Mg6 cuboctahedra, and faces with fifteen MgHf6Mg6 cuboctahedra. All Hf–Hf bond lengths are 3.05 Å. In the third Hf site, Hf is bonded to six Mg and six equivalent Hf atoms to form HfHf6Mg6 cuboctahedra that share corners with five equivalent MgHf6Mg10 cuboctahedra, corners with twelve HfHf6Mg6 cuboctahedra, edges with ten MgHf6Mg6 cuboctahedra, edges with twelve HfHf6Mg6 cuboctahedra, faces with six equivalent HfHf6Mg6 cuboctahedra, and faces with fifteen MgHf6Mg6 cuboctahedra. All Hf–Mg bond lengths are 3.26 Å. All Hf–Hf bond lengths are 3.05 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfMg by Materials Project

Mg(Hf) is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to eight equivalent Hf atoms. All Mg–Hf bond lengths are 3.02 Å. Hf is bonded in a body-centered cubic geometry to eight equivalent Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfMg by Materials Project

Mg(Hf) is Tetraauricupride structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Mg is bonded to four equivalent Mg and eight equivalent Hf atoms to form MgHf8Mg4 cuboctahedra that share corners with twelve equivalent MgHf8Mg4 cuboctahedra, edges with eight equivalent MgHf8Mg4 cuboctahedra, edges with sixteen equivalent HfHf4Mg8 cuboctahedra, faces with eight equivalent HfHf4Mg8 cuboctahedra, and faces with ten equivalent MgHf8Mg4 cuboctahedra. All Mg–Mg bond lengths are 3.12 Å. All Mg–Hf bond lengths are 3.14 Å. Hf is bonded to eight equivalent Mg and four equivalent Hf atoms to form HfHf4Mg8 cuboctahedra that share corners with twelve equivalent HfHf4Mg8 cuboctahedra, edges with eight equivalent HfHf4Mg8 cuboctahedra, edges with sixteen equivalent MgHf8Mg4 cuboctahedra, faces with eight equivalent MgHf8Mg4 cuboctahedra, and faces with ten equivalent HfHf4Mg8 cuboctahedra. All Hf–Hf bond lengths are 3.12 Å.

36 MATERIALS SCIENCE↗