Enhanced thermoelectric figure-of-merit ZT for hole-doped Bi2Sr2Co2Oy through Pb substitution

Single crystals of Bi2-xPbxSr2Co2Oy (0 <= x <= 0.55) have been grown using optical floating-zone method. The chemical compositions were determined using combined electron probe microanalysis and iodometric titration. Physical properties including electrical resistivity (rho), Seebeck coefficient (S), and thermal conductivity (kappa) were measured using single crystal specimens. Successful hole doping through Pb substitution is confirmed through combined iodometry titration, electrical transport, and Seebeck coefficient measurements. Significant reduction on both in-plane resistivity and thermal conductivity was found as a result of Pb substitution to the Bi site. The thermoelectric figure-of-merit ZT for x similar to 0.55 is raised 20 folds from the undoped sample at room temperature. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4720075]