Microstructure Evolution and Dielectric Properties of Plasma Sprayed BaTiO₃ Coatings

BaTiO₃ coatings are very promising for a wide range of applications in microelectronics because of their high dielectric constant and low leakage current. In this study, atmospheric plasma spraying is used to produce thick BaTiO₃ coatings and their microstructural features and dielectric properties are examined. The coatings were mainly composed of amorphous phase with small amounts of crystalline phase due to the incorporation of partially-molten droplets. The as-sprayed coatings were crystallized to BaTiO₃ by low temperature heat treatment and a mixture of BaTiO₃ and BaTi₂O₅ at higher temperatures. At 1200 °C, the coating formed an equiaxed grain structure due to sintering effects and the dielectric constant was significantly improved.