Compressive creep behavior of cast Bi2Te3

In thermoelectric devices, Bi2Te3 must be able to operate under high temperature gradients for very long times (years) without appreciable deformation, while being subjected to stresses created by internal thermal mismatch and external forces (e.g., vibrations). The deformation rate of cast, coarsegrained Bi2Te3 was measured under uniaxial compressive stresses from 2 to 16 MPa at temperatures between 400 and 500 1C. At all temperatures, a power-law behavior is observed, with a stress exponent n1⁄43–6 and an activation energy of 145 kJ/mol. Significant differences in creep rates are observed in duplicate experiments, which may be due to anisotropic creep resistance in coarse-grained specimens. Bi2Te3 is brittle at 400 and 450 1C but shows some compressive ductility at 500 1C, indicating that hot forging may be possible. & 2013 Elsevier B.V. All rights reserved.