High thermoelectric performance of Yb0.26Co4Sb12/yGaSb nanocomposites originating from scattering electrons of low energy

High-performance Sb excess Yb02Co4Sb12+y (y=0,03,06,10) bulk materials with nanostructure have been prepared by combining melt spinning technique with spark plasma sintering Average grain size of the bulk samples is about 150nm when y=0 and 03, and the grain size increases with the increase of y Moderately superfluous Sb may improve the electrical transport properties effectively and the thermal conductivity of the bulk samples decreases markedly due to the nanostructure The thermoelectric performance of the samples is significantly improved, and the maximum figure of the merit reaches 126 for the Yb02Co4Sb123 compound at 800K

Preparation and thermoelectric properties of high-performance Sb additional Yb0.2Co4Sb12+y bulk materials with nanostructure

A synthetic route was introduced to speed up the preparation of high performance nanostructured Yb0.3Co4Sb12+y (y=0.3 and 0.6) compounds. Compared with the samples prepared by a traditional method, the processing time is reduced from the typical 10 days to less than 40 h, the Yb filling fraction limit increases, and the resulting thermoelectric transport properties are improved significantly. As a consequence, the dimensionless figure of merit of our bulk nanostructured Yb0.3Co4Sb12.3 reaches 1.3 at 800 K. The enhanced thermoelectric performance coupled with the dramatically reduced processing time will be of considerable significance to the commercial-scale production of skutterudite-based thermoelectric materials.

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Rapid preparation method of bulk nanostructured Yb0.3Co4Sb12+y compounds and their improved thermoelectric performance

In this Review, nature-inspired binary cooperative complementary nanomaterials (BCCNMs), consisting of two components with entirely opposite physiochemical properties at the nanoscale, are presented as a novel concept for the building of promising materials. Once the distance between the two nanoscopic components is comparable to the characteristic length of some physical interactions, the cooperation between these complementary building blocks becomes dominant and endows the macroscopic materials with novel and superior properties. The first implementation of the BCCNMs is the design of bio-inspired smart materials with superwettability and their reversible switching between different wetting states in response to various kinds of external stimuli. Coincidentally, recent studies on other types of functional nanomaterials contribute more examples to support the idea of BCCNMs, which suggests a potential yet comprehensive range of future applications in both materials science and engineering.

Learning from nature: binary cooperative complementary nanomaterials.

A round robin test aiming at measuring the high-temperature thermoelectric properties was carried out by a group of European (mainly French) laboratories (labs). Polycrystalline skutterudite Co0.97 Ni 0.03Sb3 was characterized by Seebeck coefficient (8 labs), electrical resistivity (9 labs), thermal diffusivity (6 labs), mass volume density (6 labs), and specific heat (6 labs) measurements. These data were statistically processed to determine the uncertainty on all these measured quantities as a function of temperature and combined to obtain an overall uncertainty on the thermal conductivity (product of thermal diffusivity by density and by specific heat) and on the thermoelectric figure of merit ZT. An increase with temperature of all these uncertainties is observed, in agreement with growing difficulties to measure these quantities when temperature increases. The uncertainties on the electrical resistivity and thermal diffusivity are most likely dominated by the uncertainty on the sample dimensions. The temperature-averaged (300–700 K) relative standard uncertainties at the confidence level of 68% amount to 6%, 8%, 11%, and 19% for the Seebeck coefficient, electrical resistivity, thermal conductivity, and figure of merit ZT, respectively. Thermal conductivity measurements appear as the least accurate. The moderate value of the temperature-averaged relative expanded (confidence level of 95%) uncertainty of 17% on the mean of ZT is essential in establishing Co0.97 Ni 0.03Sb3 as a high temperature standard n-type thermoelectric material.

https://hal.archives-ouvertes.fr/hal-01108894/document

Invited Article: A round robin test of the uncertainty on the measurement of the thermoelectric dimensionless figure of merit of Co0.97Ni0.03Sb3

The phase equilibrium and thermoelectric properties of Co1−xNixSb3 ternary system were examined up to high nickel content x=0.40. NiSb compound with nickel arsenide structure was observed as the impurity phase in the samples with x>0.10 by x-ray diffraction. The sign of the Seebeck coefficient of Co1−xNixSb3 is negative, and the absolute value of the Seebeck coefficient and electrical resistivity generally decreases with increasing x. The thermal conductivity is reduced in the samples with x⩽0.06, but above x=0.06 it increases with increasing x. These behaviors of the thermoelectric properties in the samples with low nickel content are ascribed to the substituted Ni, while those in the samples with high nickel content are ascribed to the precipitated NiSb compound. In order to more reduce the thermal conductivity of the material, we have prepared a sintered CoSb3–NiSb composite where the NiSb particles are dispersed in the CoSb3 matrix by mechanical grinding and hot pressing. The thermal conductivity of t...

M. Watanabe

Papers

Effect of NiSb on the thermoelectric properties of skutterudite CoSb3