Anisotropy of the thermopower in higher silicide of transitions metals

A new technique for measuring the thermopower anisotropy using polycrystals on the basis of repeated measurements of an array of randomly oriented microcrystals and statistical analysis of the data obtained is proposed. The thermopower anisotropy of a series of higher silicides of transition metals $\beta$-FeSi$_{2}$, doped MnSi$_{1.75}$, ReSi$_{1.75}$, and CrSi$_{2}$) is measured using polycrystals. It is found that, in $\beta$-FeSi$_{2}$ crystals, a very high thermopower anisotropy can be observed; in ReSi$_{1.75}$ crystals, the thermopower can have different signs; and, in CrSi$_{2}$, the absolute value of the thermopower depends heavily on the heat-treatment mode. The temperature dependences of the electrical conductivity and thermopower of CrSi$_{2}$ needles are measured. The thermopower anisotropy in CrSi$_{2}$ needles, as in bulk single crystals, is retained in a wide temperature range.