Bi2Sr2Co2Oy whiskers with high thermoelectric figure of merit

Bi2Sr2Co2Oy (BC-222) whiskers were grown with an excellent Seebeck coefficient (S) and electrical resistivity (rho) for power generation applications at high temperatures in air. The S value of these long BC-222 whiskers reached almost 300 muV K-1 at 973 K. Thermal conductivity (kappa) was measured and found to be suppressed to a low value of about 2.0 W m(-1) K-1. This is considered due not only to a phonon-phonon interaction but also other scattering processes. The resulting dimensionless thermoelectric figure of merit ZT(=(ST)-T-2/rhokappa) was more than 1.1, which corresponds to a conversion efficiency of almost 10% at 973 K in air. (C) 2002 American Institute of Physics.