Hironori Uneda

High temperature thermoelectric properties of NiZrSn half-Heusler compounds

Half-Heusler compounds of the type NiZrSn1−xSbx were prepared by arc melting in the concentration range 0<x<0.3. Their high-temperature electric and thermal properties were measured. The thermoelectric power (TEP) and electrical resistivity showed a strong antimony concentration dependence. The temperature and concentration dependences of the thermoelectric properties of NiZrSn1−xSbx were studied.

Thermoelectric properties of potassium-doped β-BaCu2S2 with natural superlattice structure

We prepared polycrystalline samples of β-KxBa1−xCu2S2 (x=0,0.05,0.1) with a natural superlattice structure and measured the thermoelectric properties from room temperature to about 850K. The Seebeck coefficients are positive in the whole temperature range. The electrical resistivity and Seebeck coefficient decrease with potassium content, which indicates that potassium doping introduces charge carriers. The thermal conductivities of potassium-doped samples are slightly higher than those of undoped samples as a result of electronic contributions. The values of thermal conductivities are very low, 0.97Wm−1K−1 at room temperature for β-K0.1Ba0.9Cu2S2. The dimensionless figure of merit ZT can be improved by potassium doping and reaches 0.28 at 820K for β-K0.1Ba0.9Cu2S2.

Thermoelectric properties of Fe-V-Si Heusler type compounds

Abstract The Heusler type compounds Fe 3− x V x Si were prepared by arc melting in the concentration range between x =0 and x =1. The samples were characterized by a powder X-ray diffraction method and EDXA. The thermoelectric properties such as the thermal diffusivity, electrical resistivity, and Seebeck coefficient were measured in the temperature range from 300 to 1073 K. The thermal conductivities of Fe 3− x V x Si were evaluated from the heat capacity, experimental density, and thermal diffusivity measured by a laser flash method. A strong vanadium concentration dependence is shown in the thermoelectric power (TEP) of Fe 3− x V x Si. The temperature and vanadium concentration dependences of the thermoelectric properties of Fe 3− x V x Si were studied.