Thermoelectric properties of Co-doped BiFeO₃ and Bi₂₄CoO₃₇–BiFeO₃ compound systems

Abstract

We investigated the thermoelectric properties of doped multiferroic material: Co-doped BiFeO₃ (BFO) and related materials: Bi₂₄CoO₃₇ and Bi₂₄CoO₃₇–BFO composite systems. Because of their insulating nature, the BFO-based samples showed high Seebeck coefficients compared with other oxides being explored as candidates for new thermoelectric materials such as NaCo₂O₄, and La_0.9Sr_0.99Ca_0.11CoO₄. On the other hand, the Bi₂₄CoO₃₇ sample showed high conductivity. The Bi₂₄CoO₃₇ (20%)–BFO composite sample showed a high power factor, because of its high conductivity and high Seebeck coefficient. These results indicated that the BFO matrix plays an important role in maintaining a high Seebeck coefficient, and that Bi₂₄CoO₃₇ works as a conductive pass on this system.