Investigation of the effect of temperature on the electrical and thermoelectrical properties of silicides of some transition metals

Abstract

The authors investigated the temperature dependence of the specific electric resistance of the silicides V3Si, V5Si3, VSi2, Fe3Si, FeSi, MnSi, MnSi2, Mn5Si2, Co3Si, CoSi2, Ni3Si, Ni2Si, Re3Si, and ReSi and the absolute differential thermal-emf of the silicides V3Si, VgSis, VSi2, MnSi, Mn5Si3, MnSi2.Fe3Si, FeSi, FeSi2, Co3Si, CoSi, Ni3Si, Ni2Si, ZnSi2, and TaSi2 in the range from room temperature to 1000° (electric resistance) and 500° (thermal-emf). The silicides were obtained by direct synthesis from components; the samples for measurement, by sintering by means of the hot pressing method. The temperature dependence of the electric resistance of the suicides MnSi2 and ReSi is typical of semiconductors. The silicides Fe3Si and Co3Si may be relegated to the class of ferromagnetic semimetals. A metallic character of dependence of the resistance on the temperature was found for the other investigated suicides. The shape of the temperature vs electric resistance curves indicates the complex multiband nature of the energetic spectrum of electrons in silicides. With the increase in the relative silicon content in silicides within the given metal-silicon system, there is an increase in the absolute value of the thermal-emf, and the nature of the temperature dependence becomes more complex. The thermal-emf of Re3Si gave a zero value throughout the investigated temperature range. This substance is of practical interest as a material for contacts in high-temperature metal powder thermocouples.