Influence of synthesis conditions on the properties of electrochemically synthesized BaTiO3 nanoparticles

The continuous miniaturization of advanced electronic devices will require dielectric layers of multi-layer ceramic capacitors thinner than 500 nm in the near future. Therefore, fine barium titanate (BaTiO3) nanoparticles smaller than 100 nm are eagerly desired. Here, we synthesized BaTiO3 nanoparticles by using an electrochemical method with titanium electrodes in alkaline solution at a current of ≈3.25 A. Initially, the composition of the solvent was modified by using water or a water/methanol mixture (50:50 v/v). Methanol replacement with other compounds was subsequently tested. NaOH concentration in the electrolyte was also varied from 0.5 mol L−1 to 4.0 mol L−1. Crystal structure of the BaTiO3 was examined by using X-ray diffraction. Morphology and microstructure of the particles were studied by using scanning electron microscopy and transmission electron microscopy. Compared with conventional methods, the electrochemical synthesis enabled the production of small nanoparticles (grain sizes <200 nm) at temperatures lower than 60 °C in a short synthesis time (2 h). The particles with highest crystallinity were obtained in 1.0 mol L−1 NaOH solution in a mixture of methanol/water (50% v/v).