PROPERTIES OF SINGLE-CRYSTALLINE SEMICONDUCTING COSB3

A study of the thermoelectric properties of the skutterudite compound CoSb3 was carried out on single crystals grown by the Bridgman gradien t freeze technique. p- and n-type samples were obtained over a wide ra nge of carrier concentration, Undoped As-grown crystals show p-type co nductivity while n-type samples were obtained by addition of Te or Pd. Samples were characterized by x-ray diffractometry, electron micropro be analysis, and density measurements. The physical properties of CoSb , such as Linear thermal expansion coefficient, sound velocity, and De bye temperature were also determined and are presented. Seebeck coeffi cient, electrical resistivity, thermal conductivity, and Hall effect m easurements were performed between room temperature and about 900 K, E xceptionally high Hall mobilities were obtained on p-type samples with a maximum room-temperature Hall mobility of 3300 cm(2) V-1 s(-1) at a carrier concentration of 1 x 10(17) cm(-3). The results of the transp ort property measurements are discussed and an in agreement with some recent predictions based on band structure calculations, The potential of CoSb3 for thermoelectric applications is evaluated. (C) 1996 Ameri can Institute of Physics.