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Influence of processing parameters on the thermoelectric properties of (Bi0.2Sb0.8)2Te3 sintered by ECAE AIP Conf.Anisotropic thermoelectric characteristics of a sintered Bi,Te, system have been evaluated on the basis of the orientation distribution of crystallites. Uniaxially anisotropic resistivities, Hall coefficients, and thermal conductivities of sintered BizTe, were expressed by linear combinations of those of single crystal. The combination coefficients are specified by an anisotropy parameter that may be estimated by the anisotropy in the observed resistivities. 'Iwo types of x-ray diffraction experiments were performed to confirm the validity of the estimate. The observed diffraction intensities were reasonably consistent with the orientation distribution predicted by the anisotropy parameter. Theoretical curves of resistivities, Hall coefficients, and thermal conductivities of the sintered material were calculated by using the orientation distribution which was specified by a parameter estimated by the observed resistivities. The theoretical curves were in reasonable agreement with the observed data.

We have investigated the crystal growth of single-phase MnSi 1.75Àx by a temperature gradient solution growth (TGSG) method using Ga and Sn as solvents and MnSi 1.7 alloy as the solute, and measured the thermoelectric properties of the resulting crystals. Single-phase Mn 11 Si 19 and Mn 4 Si 7 crystals were grown successfully using Ga and Sn as solvents, respectively. The typical size of a grown ingot of Mn 11 Si 19 was 2 mm to 4 mm in thickness and 12 mm in diameter, whereas Mn 4 Si 7 had polyhedral shape with dimensions in the range of several millimeters. The single-phase Mn 11 Si 19 has good electrical conduction (q = 0.89 9 10 À3 X cm to 1.09 9 10 À3 X cm) compared with meltgrown multiphase higher-manganese silicide (HMS) crystals. The Seebeck coefficient, power factor, and thermal conductivity were 77 lV K À1 to 85 lV K À1 , 6.7 lW cm À1 K À2 to 7.2 lW cm À1 K À2 , and 0.032 W cm À1 K À1 , respectively, at 300 K.

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A calculational model is proposed to analyze the anisotropic galvanomagnetism of sintered Bi2Te3 on the basis of the orientation distribution function method. The orientation distribution of crystallites in a specimen is expressed by a distribution function of the Eulerian angle that represents the rotation of the crystallites distributed in the specimen. The distribution can be specified by a single rotation parameter because of the uniaxial anisotropy of Bi2Te3. The rotation parameter can be expressed as the angular width of the distribution by introducing the approximation that the distribution function is a Gaussian function of the tilting angle of the c axis with respect to the pressing direction of the specimen. Resistivity and Hall tensors of sintered specimens are calculated by this method to evaluate the angular width of the distribution. Theoretical curves are calculated from the data of a corresponding single crystal by estimating the distribution parameters. The theoretical curves are in reasonable agreement with the observed data.