Production of Single Crystal Thermoelectric Bismuth Telluride Alloys
Thermoelectric (TE) semiconductor materials are widely used for miniaturized versatile cooling devices in a wide spectrum of equipments and energy generation in space vehicles. The bismuth telluride pseudobinary alloy family presents the best characteristics for room temperature TE cooling applications. Using appropriately oriented single crystals instead of the well known polycrystalline materials made by powder metallurgy methods, the efficiency of the TE device (Thermoelectric Cooler – TEC or Thermoelectric Generator – TEG) could be almost doubled. For having good quality TE material it is required to produce equally doped single crystals by the controlled crystallization process, namely with the Bridgman-Stockbarber method. Our experiments were made in the Universal Multizone Crystallizator Type UMC, developed by the ADMATIS Ltd., Miskolc, using a quartz tube under high vacuum conditions and automatically controlled thermal field parameters. The crystallographic analysis of the obtained samples was made by Scanning Electron Microscopy – (SEM), X Ray Diffraction – (XRD), and neutron diffraction (TOF spectrometry).
P. J. Szabó and T. Berecz
S. I. Vallasek et al., "Production of Single Crystal Thermoelectric Bismuth Telluride Alloys", Materials Science Forum, Vol. 659, pp. 263-268, 2010