Synthesis of BaTiO3-20wt%CoFe2O4 Nanocomposites via Spark Plasma Sintering

Barium titanate-20wt% cobalt ferrite (BaTiO3-20wt%CoFe2O4) nanocomposites were sintered from nanocrystalline BaTiO3 and CoFe2O4 powders using spark plasma sintering (SPS) and pressureless sintering (PS) techniques. Using SPS, dense polycrystalline composites were obtained at a sintering temperature as low as 860 degrees C and a time of 5 similar to min whereas PS required a higher sintering temperature (1150 degrees C) and time (120 similar to min) to obtain similarly dense composites. Microstructural analysis of the composites showed that both the techniques retained nanocrystalline grain sizes after sintering. High resolution X-ray diffraction measurements revealed that the BaTiO3-20wt%CoFe2O4 composites sintered by the SPS technique did not exhibit formation of any new phase(s) due to reaction between the BaTiO3 and CoFe2O4 phases during sintering. However, the PS technique resulted in the formation of additional phases (other than the BaTiO3 and CoFe2O4 phases) in the composites. While the composites synthesized by SPS were of superior phase-purity, evidence of Fe diffusion from the spinel to the perovskite phase was found from X-ray diffraction and permittivity measurements.