Conductivity studies of Ni and Gd substituted BiCoO_3

摘要

In this paper, we report the synthesis, thermal and electrical property studies of Ni_(0.5)Gd_(0.2)Bi_(0.3)CoO_3, a new material for thermoelectric applications. The material was synthesized by solid state reaction route taking BiCoO_3 as basic matrix by substituting bismuth with nickel and gadolinium. Structural studies using room temperature XRD and room temperature Raman spectrum established cubic structure for Ni_(0.5)Bi_(0.5)CoO_3 and tetragonal structure for Ni_(0.5)Gd_(0.2)Bi_(0.3)CoO_3. The SEM micrograph of the samples revealed crystallites of micrometer dimension with varying grain size. The sample showed interestingly low thermal conductivity and VRH mechanism was found to dominate in the electrical conduction at low temperature regime. The low thermal conductivity and moderate electrical conductivity is suggestive of strong candidature of the material for thermoelectric applications.