Dislocations were found having an uniquely high mobility at room temperature. The gliding dislocations were analysed, and their effect upon the thermoelectric properties was considered. Glide of the dislocations was induced by heating with a focused electron beam at 120keV. No external stresses were applied. The dislocations bowed out in the glide direction and were pinned only at the sample surface. Stereomicroscopy and image simulation yielded basal plane dislocations with a density of 109/cm2 and Burgers vectors of <110> type. Video recordings showed the glide of single dislocations and groups of dislocations. Isolated dislocations exhibited a high mobility in ±<110> directions, with a velocity of 10 to 100nm/s. Dislocation dipoles were pinned and did not glide. Dislocations equidistantly arranged within the same glide plane underwent collective movement. Dislocations piled up in different glide planes were fixed and acted as barriers to gliding dislocations. The motion of dislocations was attributed to residual shear stresses of about 10MPa, and their glide directions depended upon the sign of the Burgers vector. Attractive and repulsive forces of dislocations directly revealed the forces due to the elastic strain fields of other dislocations. The relevance of phonon scattering to dislocations in Bi2Te3, particularly due to their high mobility and density, was confirmed. Firstly, dislocations decreased the lattice thermal conductivity due to phonon scattering on the elastic strain field. The phonon mean free path was estimated to be about 800µm at 3K and agreed with published data. The dislocation resonance theory of Granato and Lücke predicted an interaction between phonons and dislocations acting as oscillating strings. The attenuation of ultrasound was estimated and was compared with published data.

Gliding Dislocations in Bi2Te3 Materials. N.Peranio, O.Eibl: Physica Status Solidi A, 2009, 206[1], 42-9