Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in YbMnSb and YbMgSb.

The Zintl phases, Yb Sb ( = Mn, Mg, Al, Zn), are now some of the highest thermoelectric efficiency p-type materials with stability above 873 K. YbMnSb gained prominence as the first p-type thermoelectric material to double the efficiency of SiGe alloy, the heritage material in radioisotope thermoelectric generators used to power NASA's deep space exploration. This study investigates the solid solution of YbMg Al Sb (0 ≤ ≤ 1), which enables a full mapping of the metal-to-semiconductor transition.

Structural Insights on Microwave-Synthesized Antimony-Doped Germanium Nanocrystals.

Doped and alloyed germanium nanocrystals (Ge NCs) are potential candidates for a variety of applications such as photovoltaics and near IR detectors. Recently, bismuth (Bi) as an -type group 15 element was shown to be successfully and kinetically doped into Ge NCs through a microwave-assisted solution-based synthesis, although Bi is thermodynamically insoluble in bulk crystalline Ge. To expand the composition manipulation of Ge NCs, another more common -type group 15 element for semiconductors, antimony (Sb), is investigated.

Ambient and High Pressure CuNiSb: Metal-Ordered and Metal-Disordered NiAs-Type Derivative Pnictides.

The mineral Zlatogorite, CuNiSb, was synthesized in the laboratory for the first time by annealing elements at ambient pressure (CuNiSb-AP). Rietveld refinement of synchrotron powder X-ray diffraction data indicates that CuNiSb-AP crystallizes in the NiAs-derived structure (31, #164) with Cu and Ni ordering. The structure consists of alternate NiSb and CuSb octahedral layers via face-sharing.

Hydride Synthesis and Thermoelectric Properties of Type-I Clathrate KEGe (E = Al, Ga, In).

Type I clathrates of the composition KEGe (E = Al, Ga, In) were prepared via the reaction of KH with E and Ge and thermoelectric properties measured in order to compare to KAlSi, a promising thermoelectric material. The structures were confirmed with Rietveld refinement of powder diffraction patterns obtaining lattice parameters of 10.7729(2) Å, 10.

Earth Abundant Element Type I Clathrate Phases.

Earth abundant element clathrate phases are of interest for a number of applications ranging from photovoltaics to thermoelectrics. Silicon-containing type I clathrate is a framework structure with the stoichiometry ASi (A = guest atom such as alkali metal) that can be tuned by alloying and doping with other elements. The type I clathrate framework can be described as being composed of two types of polyhedral cages made up of tetrahedrally coordinated Si: pentagonal dodecahedra with 20 atoms and tetrakaidecahedra with 24 atoms in the ratio of 2:6.