Fabrication of the Crystal-Oriented Thermoelectric Material Bi₂Te₃ by Slip Casting under a High Magnetic Field

Abstract

It is well known that the electric and thermal conductivities of materials depend largely on their crystal orientation. Meanwhile, the imposition of a high magnetic field is a very effective method of obtaining highly crystal-aligned structures. Recently, thermoelectric materials, that is, materials which can directly convert electrical energy to thermal energy and vice versa, have attracted significant attention for their potential uses in solving environmental problems.
In this study, highly crystal-aligned structures of Bi₂Te₃ compact were prepared by introducing crystal alignment into a green sample by conducting slip casting under a high magnetic field, followed by compaction by pulse-discharge sintering (PDS). By aligning the crystal orientation, electric resistivity was reduced, while the Seebeck coefficient maintained a value nearly identical to that of non-aligned crystals. The reference value of a dimensionless figure of merit as high as 1.3 at 323 K was obtained.