Effect of Ba and Pb dual doping on the thermoelectric properties of BiCuSeO ceramics.

The layered oxyselenide BiCuSeO thermoelectric ceramics are attracting more and more attention due to intrinsically low thermal conductivity. In this work, Bi 1−x−y Ba x Pb y CuSeO (x = y = 0, 0.01, 0.02, 0.04, 0.06, 0.08; x = 0, y = 0.08; x = 0.08, y = 0) bulks have been prepared by mechanical alloying (MA) and resistance pressing sintering (RPS) process, and the effects of Ba/Pb doping on the thermoelectric properties and Vickers hardness of p-type BiCuSeO ceramics have been investigated systematically. The results indicated that the substitution of Bi 3+ by Ba 2+ /Pb 2+ resulted in the significantly increase of electrical conductivity and power factor due to the introduction of the carriers into the conductive (Cu 2 Se 2 ) 2− layers as the result of the introduction of negative charge into the carrier-storaging (Bi 2 O 2 ) 2+ layers. Specifically, the room temperature electrical conductivity significantly increases from ∼8 Scm −1 for pristine BiCuSeO to ∼244 Scm −1 for Bi 0.92 Ba 0.04 Pb 0.04 CuSeO, and further up to ∼443 Scm −1 for Bi 0.84 Ba 0.08 Pb 0.08 CuSeO. The maximum power factor of 0.66 mWm −1 K −2 and dimensionless figure of merit (ZT) value of 1.01 were obtained for the Bi 0.88 Ba 0.06 Pb 0.06 CuSeO at 873 K. [ABSTRACT FROM AUTHOR]