BRIDGMAN-SOLUTION CRYSTAL-GROWTH AND CHARACTERIZATION OF THE SKUTTERUDITE COMPOUNDS COSB3 AND RHSB3

Compounds with the skutterudite structure have recently been identifie d as advanced thermoelectric materials. We report on the crystal growt h and characterization of the skutterudite compounds CoSb3 and RhSb3 w hich form peritectically at 873 and 900 degrees C, respectively. Large single crystals were obtained by the vertical gradient freeze techniq ue from solutions rich in antimony. The samples were characterized by high-temperature Hall-effect and electrical resistivity measurements. Bandgaps of 0.56 and 0.80 eV were estimated from these measurements fo r CoSb3 and RhSb3, respectively. N-type CoSb3 samples were obtained by doping with Te. Exceptionally high p-type Hall-mobility values have b een measured and a room-temperature value of 3445 cm(2) V-1 s(-1) was obtained for CoSb3 at a carrier concentration of 4 x 10(17) cm(-3) and 8000 cm(2) V-1 s(-1) was obtained for RhSb3 at a carrier concentratio n of 3.5 x 10(18) cm(-3).