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

[Display omitted] •Ba/Pb dual doping led to the great increase of carrier concentration and electrical conductivity.•The maximum dimensionless figure of merit (ZT) value of 1.01 were obtained for Bi0.88Ba0.06Pb0.06CuSeO at 873 K.•The Vickers hardness of pristine BiCuSeO is ∼201 HV, and increases with Ba/Pb doping. The layered oxyselenide BiCuSeO thermoelectric ceramics are attracting more and more attention due to intrinsically low thermal conductivity. In this work, Bi1−x−yBaxPbyCuSeO (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 Bi3+ by Ba2+/Pb2+ resulted in the significantly increase of electrical conductivity and power factor due to the introduction of the carriers into the conductive (Cu2Se2)2− layers as the result of the introduction of negative charge into the carrier-storaging (Bi2O2)2+ layers. Specifically, the room temperature electrical conductivity significantly increases from ∼8 Scm−1 for pristine BiCuSeO to ∼244 Scm−1 for Bi0.92Ba0.04Pb0.04CuSeO, and further up to ∼443 Scm−1 for Bi0.84Ba0.08Pb0.08CuSeO. The maximum power factor of 0.66 mWm−1K−2 and dimensionless figure of merit (ZT) value of 1.01 were obtained for the Bi0.88Ba0.06Pb0.06CuSeO at 873 K.