Polyethyleneimine surfactant effect on the formation of nano-sized BaTiO₃ powder via a solid state reaction

Barium titanate powder is widely used in multilayer ceramic capacitors (MLCC) because of its' superior ferroelectric and dielectric properties. Presently, barium titanate powder is mass-produced using a conventional solid state reaction. However, the conflicting literature reports clearly show that the solid state reaction mechanism is not well understood. Synthesizing nano-sized barium titanate powders with less agglomeration using a solid state reaction method at a low calcination temperature has become a hot research topic. This study examines the effect of polyethyleneimine (PEI) surfactant addition on BaTiO₃ formation in a solid sate reaction. XRD, DTA and TEM are used in this investigation. The results indicate that PEI addition can promote BaCO₃ and TiO₂ mixing homogeneity, which enhances the interfacial reaction between BaCO₃ and TiO₂. BaTiO₃ formation can be obtained through the interfacial reaction between BaCO₃ and TiO₂ at the intimate contact between the reactants and Ti⁺⁴ ion diffusion along the surfaces or grain boundaries of BaTiO₃ powders, thereby obtaining a single phase BaTiO₃ powder when calcining at low temperatures for a long period.