Synthesis, spark plasma sintering and electrical conduction mechanism in BaTiO3-Cu composites

BaTiO3-Cu composite powders were prepared via an alkoxide-mediated synthesis approach. As-synthesized BaTiO3 nanoparticles were as small as 40 nm and coated partially larger Cu particles of approximately 1 μm in size. Thermogravimetric analysis (TGA) and dilatometry revealed a gradual increase in weight loss and retarded shrinkage with the increase of Cu addition. BaTiO3-Cu composites were successfully densified by spark plasma sintering (SPS). The microstructures show an average grain-size for BaTiO3 of around 100 nm and a crystallite size of about 1 μm for the Cu inclusions. The AC conductivity of the BaTiO3-Cu composites increased with increasing Cu content or with temperature. The dominant electrical conduction mechanism in SPSed BaTiO3-Cu composites changed from migration of oxygen vacancies to band conduction of trapped electrons in oxygen vacancies with the increase of Cu content.