Preparation of conventional thermoelectric nanopowders by pulsed laser fracture in water: application to the fabrication of a pn hetero-junction

The technique of laser fracture in a liquid medium has been applied to the synthesis of n-type (Bi0.95Sb0.05)2 (Te0.95Se0.05)3 and p-type (Bi0.2Sb0.8)2Te3 semiconducting nanopowders which are the best conventional materials currently used for thermoelectric applications at ambient temperature. The nanopowders have been prepared with a high yield in an especially built-up cell. Laser fracture in water of micronsized powders has been applied, using a nanosecond Nd:YAG laser working at 532 nm. The obtained powders have been characterized by scanning and transmission electron microscopy and by X-ray diffraction. The mean diameter is about 10 nm and the phase of the initial powders is kept. To test the potentiality of these nanosized materials, we have shown the feasibility to produce a pn hetero-junction.