Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Ba(CuTe)2”

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.

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ba(CuTe)2 by Materials Project

BaCu2Te2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ba2+ is bonded in a 7-coordinate geometry to seven Te2- atoms. There are a spread of Ba–Te bond distances ranging from 3.43–3.62 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four Te2- atoms to form a mixture of edge and corner-sharing CuTe4 tetrahedra. There are a spread of Cu–Te bond distances ranging from 2.66–2.72 Å. In the second Cu1+ site, Cu1+ is bonded to four Te2- atoms to form a mixture of edge and corner-sharing CuTe4 tetrahedra. There are a spread of Cu–Te bond distances ranging from 2.62–2.80 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 7-coordinate geometry to three equivalent Ba2+ and four Cu1+ atoms. In the second Te2- site, Te2- is bonded in a 8-coordinate geometry to four equivalent Ba2+ and four Cu1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

A Ba 6 Cu 31 Te 22 ( A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

In this study, hree polyanionic tellurides, ABa 6 Cu 31 Te 22 (A = K, Rb, Cs), were synthesized in salt flux. The isostructural tellurides crystallize in a new structure type, in the cubic Pa$\overline{3}$ space group with a Wyckoff sequence of d 10 c 2 b 1 and large unit cell volumes of over 5500 Å 3 . The structures feature a framework of [CuTe 4 ] tetrahedra and [CuTe 3 ] trigonal pyramids with disorder in the Cu sites. The polyanionic frameworks have large square antiprism and cuboctahedral voids where Ba and alkali metal cations are situated, forming [BaTe 8 ] and [ATe 12 ], respectively. The overall compositions are close to being charge balanced. The large [ATe 12 ] cuboctahedra allowed for significant anisotropic displacement of the A cations, as observed from both single crystal X-ray diffraction and heat capacity studies. Alkali cations rattling together with Cu atom displacement and disorder leads to the dispersion of phonons, thus softening the lattice and subsequently reducing the thermal conductivity. Evaluations of the electronic band structure revealed the occurrence of a narrow bandgap together with the presence of a flat band near the valence band maximum, giving rise to the high thermopower. The Cs and Rb analogues show a slope change in the temperature dependence of electrical resistivity around room temperature, which is typical for semimetals or degenerate semiconductors. For the as-synthesized and unoptimized materials, high values of the thermoelectric figure-of-merit of ~0.2 were observed at 623 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗