Electrical transport and thermoelectric study of Ca3Co4O9 ceramics

Abstract The study of thermoelectric materials, which convert thermal energy to electrical energy in the solid state, has grown immensely in the past decade. The polycrystalline Ca3Co4O9 powder were synthesized using conventional sold state route by employing double sintering method. Homogeneous mixture in stoichiometric proportion of CaCo3 and Co3O4 powder was ground for 3 hrs and sintered at 1100 °C for 24 hrs with several intermediate grindings. The electrical transport property such as temperature dependent resistivity and thermoelectric seebeck coefficient was measured in the temperature range RT to 623 K. The electrical resistivity decreases with increasing temperature showing the semiconductor behaviour. The resistivity behaviour is fitted and explained using Thermal activation model and small polaron hopping (SPH) model. The value of seebeck coefficient (S) measured from room temperature to 623 K and it is found to be ∼42.7 μV/K. Ca3Co4O9 is thermoelectrically potential material for waste heat retrieval energy applications.