Electrophoretic deposition of Ca₂Nb₃O₁₀^- nanosheets synthesized by soft-chemical exfoliation

Ca₂Nb₃O₁₀^- (CNO^-) nanosheets exfoliated from a KCa₂Nb₃O₁₀ ceramic were deposited on a Pt/Ti/SiO₂/Si substrate at room temperature (RT) using the electrophoresis method, and subsequently annealed at various temperatures to remove organic defects. The inter-planar distance of the (001) plane of the CNO film deposited at RT was large (1.68 nm). This distance gradually decreased to 1.44 nm when the annealing temperature was increased to 600°C due to the removal of organic defects. For CNO films annealed at temperatures higher than 600°C, a CaNb₂O₆ secondary phase was formed, indicating that annealing should be conducted at 600°C to obtain a homogeneous CNO film. Moreover, the CNO film annealed at 600°C showed a large ε_r value of 65 with a low tanδ of 0.01 at 1.0 MHz. This film also exhibited a high breakdown electric field of 0.43 MV cm^-1 and a very low leakage current density of 3 × 10^-8 A cm^-2 at 0.4 MV cm^-1.