Synthesis and Characterization of Bi₄Ti₃O₁₂ Thin Films by Sol-Gel Processing

Abstract

Stoichiometric Bi 4 Ti 3 O 12 thin films were prepared by sol-gel processing. This paper discusses the synthesis of polymerizable solutions containing Bi and Ti, and characterization of the resulting Bi 4 Ti 3 O 12 thin films. The formation of metallic alkoxide and acetate alkoxide are indispensable, soluble precursors for these multicomponent systems. The double alkoxide was prepared by allowing Bi acetate to react with Ti alkoxides. The development of the polymerizable solution system containing Bi and Ti required choosing appropriate solvents and metallo-organic sources for the two components. Bismuth acetate, titanium methoxyethoxide and the solvents 2-methoxyethanol and glacial acetic acid were selected based on their successful use in a number of related systems. Thin films of Bi 4 Ti 3 O 12 were obtained onto platinized Si substrates by spin casting, followed by heat-treated at 700°C. These films were later characterized by X-ray diffraction and SEM. The measured dielectric and ferroelectric properties of Bi 4 Ti 3 O 12 were as follows: dielectric constant 120, dielectric loss 0.5%, remanent polarization P r =4 µC/cm 2 , coercive field E c =1.8 kV/cm.