Thermoelectric properties of single crystalline B4C prepared by a floating zone method

High-purity single crystalline B4C, several cm in size, has been prepared by a Floating Zone method. The electrical conductivity, Hall mobility, Seebeck coefficient and thermal conductivity are measured from room temperature to 1023 K. The electrical conductivity is about four times higher than that of sintered B4C. The mobility has increased with increasing temperature, indicating hopping conduction of charge carriers. The Seebeck coefficient is 240-260 mu VK-1, almost independent of temperature. The thermal conductivity is about twice higher than that of sintered B4C. The thermoelectric figure-of-merit is also higher than that of sintered B4C, being 4.2 x 10(-5) K-1 at 1100 K.