Recent developments in soft, solution processing: one step fabrication of functional double oxide films by hydrothermal-electrochemical methods

Abstract

Based upon thermodynamic considerations, we propose ‘soft, solution processing’, as a means to fabrication of shaped, sized, and controlled advanced materials from aqueous solutions without excess heat, energy consumption, expensive equipment, and precursor(s) as one of the most economical and environmentally friendly preparation techniques for advanced materials. We have succeeded in the fabrication of double oxide thin films such as BaTiO ₃ , SrTiO ₃ , their solid solutions, and LiNiO ₂ at fixed temperatures between 60 and 150 °C by hydrothermal–electrochemical methods. Nucleation and growth of the films takes place at the interface between the alkaline (earth) component in the solutions and anodically treated metal plates. The structures and properties of these films are described. A novel method to fabricate BaTiO3, SrTiO3, their solid solutions, and LiNiO2 at fixed temperatures between 60 and 150 °C by hydrothermal-electrochemical methods. Nucleation and growth of the films takes place at the interface between the alkaline (earth) component in the solutions and anodically treated metal plates. The structures and properties of these films are described. A novel method to fabricate BaTiO ₃ /SrTiO ₃ layered thin films by changing the solution compositions in flow-cell equipment is presented.