Crystal growth and anisotropy of high temperature thermoelectric properties of yttrium borosilicide single crystals

We studied thermoelectric properties of YB41Si1.3 single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers, with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also. The growth direction ([510]) was determined for the first time in YB41Si1.3 single crystals and revealed an interesting layered feature of boron clusters and metal atoms, along which the electrical conductivity and thermoelectric power factor was strongly enhanced. [Display omitted] •We have grown YB41Si1.3 single crystals by the floating zone method.•Growth direction of [510] determined for first time in REB41Si1.2.•Electrical resistivity was strongly anisotropic with possible enhancement along metal layers.•The obtained power factor along [510] is 3.6 times higher than that along [052].