Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “MgNiSb”

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.

Materials Data on MgNiSb by Materials Project

MgNiSb is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent Sb3- atoms to form MgSb6 octahedra that share corners with six equivalent MgSb6 octahedra, corners with twelve equivalent NiSb4 tetrahedra, edges with twelve equivalent MgSb6 octahedra, and faces with four equivalent NiSb4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–Sb bond lengths are 3.04 Å. Ni1+ is bonded to four equivalent Sb3- atoms to form NiSb4 tetrahedra that share corners with twelve equivalent MgSb6 octahedra, corners with twelve equivalent NiSb4 tetrahedra, and faces with four equivalent MgSb6 octahedra. The corner-sharing octahedral tilt angles are 55°. All Ni–Sb bond lengths are 2.63 Å. Sb3- is bonded in a 10-coordinate geometry to six equivalent Mg2+ and four equivalent Ni1+ atoms.

36 MATERIALS SCIENCE↗

Opening the Bandgap of Metallic Half-Heuslers via the Introduction of d–d Orbital Interactions

Half-Heusler compounds with semiconducting behavior have been developed as high-performance thermoelectric materials for power generation. Many half-Heusler compounds also exhibit metallic behavior without a bandgap and thus inferior thermoelectric performance. Here, taking metallic half-Heusler MgNiSb as an example, a bandgap opening strategy is proposed by introducing the d–d orbital interactions, which enables the opening of the bandgap and the improvement of the thermoelectric performance. The width of the bandgap can be engineered by tuning the strength of the d–d orbital interactions. The conduction type and the carrier density can also be modulated in the Mg 1- x Ti x NiSb system. Both improved n-type and p-type thermoelectric properties are realized, which are much higher than that of the metallic MgNiSb. The proposed bandgap opening strategy can be employed to design and develop new half-Heusler semiconductors for functional and energy applications.

36 MATERIALS SCIENCE↗