Pressure induced enhancement in the thermoelectric and mechanical properties of Ni-doped skutterudites during spark plasma sintering

Effect of applied pressure during reactive spark plasma sintering (RSPS) of undoped and Ni-doped CoSb3skutterudite samples on their thermoelectric and mechanical properties is reported. Undoped and Ni-doped CoSb3 samples (CoSb3, Ni0.1Co0.9Sb3 and Ni0.2Co0.8Sb3) were processed using ball milling followed by RSPS at two different applied pressures of 50 MPa and 80 MPa. Electrical conductivity and thermopower of the samples processed at 80 MPa are enhanced substantially than those processed at 50 MPa. As a result, the thermoelectric power factor at 773 K for Ni0.2Co0.8Sb3 processed at 50 MPa is increased from 2 mW/mK2 to 3.3 mW/mK2 processed at 80 MPa, the highest value of unfilled Ni-doped CoSb3skutterudites reported so far. Nanomechanical testing reveals the significant improvement of the Young’s modulus and mechanical properties of the samples processed at 80 MPa. Our results show that the materials can be used in the thermoelectric device for waste heat recovery applications.