Influences of water content on synthesis of (Pb_0.5,Ba_0.5)TiO₃ materials using acetylacetone as chelating agent in a sol-gel process

Ferroelectric (Pb_0.5,Ba_0.5)TiO₃ (PBT) nanometric sized powders and thin films can be synthesized by a sol-gel process incorporating acetylacetone as a chelating agent to form ligands with titanium isopropoxide. The water contents were varied to investigate the resulting effects on the properties of the PBT powders. It was found that at a lower content of water, a slower rate of hydrolyzation and polycondensation occurred, therefore, a less cross-linking gel that pyrolyzed easily was observed. This less cross-linking gel could be converted to perovskite PBT at temperatures as low as 450 °C. A high purity of perovskite powder was obtained at 500 °C, with a nano-meteric size of about 30-50 nm the specific surface area of 21.91 m²/g. PBT thin films with polycrystalline or highly preferred orientation were prepared using the as-prepared optimal sol spin coating on (1 0 0) Si or (1 0 0) MgO substrate, respectively. The films were smooth, good quality and crack-free.