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The phase equilibrium and thermoelectric characteristics of Co(sub 1-x)Fe(sub x)Sb(sub 3) ternary system up to high iron context were investigated. Traces of Sb were found in the hot-pressed samples with x >/= 0.06 and FeSb2 compound with marcasite structure was also found in the samples wih x >/= 0.25 by x-ray diffraction. The lattice parameter of Co(sub 1-x)Fe(sub x)Sb3 was slightly bigger than that of the binary compound CoSb3.

A study was conducted on the effect of substitution of La by alkaline earth metal on the phase stability and thermoelectric properties of gamma-La3S4. The findings indicate that the Seebeck coefficient and electrical resistivity increase and thermal conductivity decreases with an increase of x. Moreover, the substitution for La by alkaline earth metal of La3S4 results in a stable Th3P4-type structure at high temperature.

The phase equilibrium and thermoelectric properties of Co[sub 1-x]Ni[sub x]Sb[sub 3] 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 Co[sub 1-x]Ni[sub x]Sb[sub 3] 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 CoSb[sub 3]-NiSb composite where the NiSb particles are dispersed in the CoSb[sub 3] matrix by mechanical grinding and hot pressing. The thermal conductivity of the composite is lower than that of the Co[sub 1-x]Ni[sub x]Sb[sub 3] system especially at low temperature. The decrease of the thermal conductivity is ascribed to the enhancement of the phonon scattering caused by the dispersion of NiSb particles in the CoSb[sub 3] matrix. [ABSTRACT FROM AUTHOR]

(Zn[sub 1-y]Mg[sub y])[sub 1-χ]Al[sub χ]O powders were synthesized by the polymerized complex method and then consolidated by spark plasma sintering apparatus. The microscopic structure and thermoelectric properties were examined comparing with the experimental results of the samples prepared by the conventional solid-state reaction method. A small amount of ZnAl[sub 2]O[sub 4] spinel phase as the second phase was observed in the sintered samples with x ≥ 0.02 by x-ray diffraction and a scanning electron microscope. The grain size of the samples prepared by the polymerized complex method is much smaller than that of the samples prepared by the conventional solid-state reaction method. The absolute values of the Seebeck coefficient and electrical resistivity decrease with increasing x up to about χ = 0.01, but above χ = 0.01 they are almost independent of χ. This result indicates that the solubility limit of Al in Zn[sub 1-χ]Al[sub χ]O is about χ = 0.01, which is also confirmed by [sup 27]Al nuclear magnetic resonance spectroscopy. At a fixed composition of χ, the absolute values of the Seebeck coefficient and electrical resistivity for the samples prepared by the polymerized complex method are smaller than those for the samples prepared by the solid-state reaction method, which indicates that the doping of the carrier into the material can be more easily realized in the samples prepared by the polymerized complex method. The thermal conductivity decreases with increasing χ, but the further suppression of the thermal conductivity was attained by the additional substitution on the Zn site by Mg. The Seebeck coefficient of (Zn[sub 1-y]Mg[sub y])[sub 1-χ]Al[sub χ]O is almost independent of Mg content y, but the electrical resistivity increases with increasing y. As a result, (Zn[sub 0.90]Mg[sub 0.10])[sub 0.9975]Al[sub 0.0025]O shows a maximum dimensionless figure of merit of 0.10 at 1073 K. [ABSTRACT FROM AUTHOR]

Studies the thermoelectric properties of CoSb[sub 3]-FeSb[sub 2] composite where FeSb[sub 2] particles are dispersed in the CoSb[sub 3] matrix by mechanical grinding. Effect of mechanical grinding on the thermoelectric properties of CoSb[sub 3]; Effect of mechanical grinding on the thermoelectric properties of the CoSb[sub 3]-FeSb[sub 2] composite.

Examines the phase equilibrium and thermoelectric properties of a skutterudite compound ternary system up to high iron context. Details on the experiment; Results and discussions.

A silicide material with a good n-type thermoelectric property has been discovered. This silicide possesses a composition of Mn3-xCrxSi4Al2 (0 ≤ x ≤ 0.7) and hexagonal CrSi2 structure. The a- and c-cell parameters decrease with increasing the amount of Cr substitution. The absolute values of Seebeck coefficient and electrical resistivity increase by Cr substitution up to 573 K because of reduction of carrier density. The dimensionless thermoelectric figure of merit ZT reaches 0.21 at 773 K for a non Cr substituted sample at the Mn site and 0.30 at 573 K for a Cr substituted one with x = 0.3. Since oxide passive layer is formed around the surface, electrical resistivity measured at 873 K is constant for 2 days in air, which indicates good oxidation resistance in air of this material. The Mn3-xCrxSi4Al2 is a promising n-type material with a good oxidation resistance in the middle temperature range. A thermoelectric module consisting of 64 pairs of legs has been fabricated using MnSi1.7 and non Cr substituted Mn3Si4Al2 devices as p- and n-type legs, respectively. Output power reaches 9.4 W, which corresponds to 2.3 kW/m2 of power density against surface area of the substrate, for a heat source temperature of 873 K in air. [ABSTRACT FROM AUTHOR]