Effect of Pb(BO2)2 Doping on Power Factor of Bi2Sr2Co1.8Oy Thermoelectric Ceramics

In this work, Pb(BO2)(2)-doped Bi2Sr2Co1.8Oy thermoelectric materials with composition Bi2-x[Pb(BO2)(2)](x)Sr2Co1.8Oy (x = 0, 0.075, 0.15, 0.25) were prepared through the solid-state reaction method. Electron transport and microstructural characteristics of prepared materials were studied, and values of their power factor were calculated. It was found that the slight doping of Bi2Sr2Co1.8Oy with lead borate leads to the decrease in electrical resistivity at 923 K from 126 to 76.5 m Omega cm for x = 0.15. The resistivity increases upon further Pb(BO2)(2) doping for x = 0.25. The increase in the Seebeck coefficient was observed with an increase in dopant content from x = 0.15 up to 0.25. The Pb(BO2)(2) doping resulted in a 1.8-fold enhancement of the power factor from 21.7 mu W/(m K-2) at 923 K in the reference sample to 38.2 mu W/(m K-2) in the doped sample with x = 0.15. Partial substitution of Bi2O3 by Pb(BO2)(2) also promotes both grain growth and densification of Bi2Sr2Co1.8Oy thermoelectric ceramics.