Electrical transport properties of Cu_2Se dispersed and Na-doped Bi_2Ba_2Co_2O_y thermoelectric composites

摘要

The Cu_(2-x)Se nanopowder was synthesized by the hydrothermal method. The electrical transport properties of Bi_(1.975)Na_(0.025)Ba_2Co_2O_y +xwt% Cu_2Se (x = 0.00, 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50) ceramic samples prepared by the solid-state reaction method were investigated from 300 K to 898 K. The Cu_(2-x)Se dispersant with an appropriate amount played an important role in reducing resistivity. Although the Seebeck coefficients decreased slightly, the power factors of the doped samples got a significant improvement. Ultimately, the Bi_(1.975)Na_(0.025)Ba_2Co_2O_y + 0.25wt% Cu_2Se sample exhibited a better power factors (PF) of 191.8 (10~(-6)W~(-1)mK~(-2)) at 898 K, which was improved by 31% compared with the un-doped Bi_2Ba_2Co_2O_y sample.