Electrical and dielectric properties of (Ba0.5Sr0.5)TiO3 thin films prepared by a hydroxide-alkoxide precursor-based sol-gel method

Thin films of barium strontium titanate with composition (Ba0.5Sr0.5)TiO3 were prepared by a sol-gel method using Ba-, Sr-hydroxides, titanium(IV) isopropoxide as source materials and 2-methoxyethanol as the solvent. Well-crystallised films were obtained at relatively low temperatures. We observed grain growth accompanied with increase in the dielectric constant as the annealing temperature increased. The films prepared from this method and annealed at 800degreesC showed high dielectric constant of 650. Typical leakage current density of the film annealed at 700degreesC is 0.8 x 10(-6) at 75 W cm(-1). The change in electrical characteristics of the films has been correlated to their microstructure, which revealed that the concentration change affected the film porosity and grain size distribution. The results indicate that the microstructure could be tailored by changing the precursor solution concentration. (C) 2002 Elsevier Science B.V. All rights reserved.