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We examined the effects of Si and Al content of Fe-Si-Al alloy powders with respect to the temperature dependence of core loss in order to find an optimum composition that achieves both negative temperature dependence of core loss and good permeability. By reducing the Si content from the 9.6 mass% of conventional Sendust alloy composition to 7.9-8.9 mass%, the temperature dependence of core loss became negative and maintained the high permeability of the Sendust powder core. The optimum composition was 8.8 mass% Si and 6.0 mass% Al, yielding a core loss value of 240 kW/[m.sup.3] at 373 K, about half that of the conventional Sendust powder core. Index Terms--Iron alloys, losses, permeability, powdered magnetic materials.

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.

(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.