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.