Thermoelectric properties of Mn- and Co-doped Ã\x9f-FeSi2 single crystals

Co-doped and Mn-doped beta-FeSi₂ single crystals were grown by temperature gradient solution growth method using Ga as a solvent. Polyhedral shaped bulk crystals with well developed facets could be obtained. In particular, Co-doped single crystals which are large enough to measure the Seebeck coefficient along crystallographic axes were obtained. We determined the crystal orientation by Laue back reflection pattern, and measured the Seebeck coefficients of the Co-doped beta-FeSi₂ along the three orthorhombic crystal axes. The Seebeck coefficient along the a-axis was somewhat lower than the others, while that of the previously reported non-doped beta-FeSi ₂ was the highest among the three directions. In addition, the anisotropy of the Co-doped beta-FeSi₂ was weaker compared with that of non-doped ones