Enhanced thermoelectric properties in BiCuSeO ceramics by Pb/Ni dual doping and 3D modulation doping

Abstract

Bi1-xPbxCu1-xNixSeO (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) BiCuSeO based ceramics have been prepared by mechanical alloying (MA) and resistance pressing sintering (RPS) process. The effects of Pb/Ni doping and 3D modulation doping on the thermoelectric properties have been investigated systematically. For Pb doping, it can tune the Fermi level and promote the band convergence, decreasing the band gap and significantly enhancing the carrier concentration. Besides, it contributes to higher effective mass and Seebeck coefficient due to the delocalized 6s orbitals from the lone pair electrons. For Ni doping, Ni ions could enhance Seebeck coefficient. The results indicates that the substitution of Pb at Bi site and Ni at Cu site resulted in the significantly increase of electrical conductivity and power factor. Based on this, 3D modulation doping led to the simultaneous increase of the electrical conductivity and power factor. The maximum power factor of the modulation doped sample (Bi0.90Pb0.10Cu0.90Ni0.10SeO) reached 0.64 mW m−1 K−2, and the maximum ZT value reached 1.08, which is 1.3 and 1.0 times higher than those of the undoped sample, respectively.