Fabrication and dielectric properties of the BaTiO3–polymer nano-composite thin films

✍ Scribed by Y. Kobayashi; T. Tanase; T. Tabata; T. Miwa; M. Konno

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 772 KB
• Volume: 28
• Category: Article
• ISSN: 0955-2219
• DOI: 10.1016/j.jeurceramsoc.2007.05.007

✦ Synopsis

To prepare high dielectric thin film of polymer-based materials, nanometer sized barium titanate (BaTiO 3 ) particles, which should have high dielectric coefficients and low energy dissipation factors due to nano-size effects, were dispersed in polyvinylidene fluoride (PVDF) or siloxanemodified polyamideimide (SPAI). The BaTiO 3 particles with crystal sizes of 10.5-34.6 nm were synthesized with a complex alkoxide method. Polymer/N-methyl-2-pyrrodinone solution suspending the BaTiO 3 particles was spin-coated on ITO glass substrates to prepare polymer-based composite films with thickness of submicron meters. The BaTiO 3 particles were dispersed more homogeneously in the PVDF film than in the SPAI film. The good dispersion of the particles in the PVDF film brought about a smooth surface of the film that had a root mean square roughness less than 20 nm at a particle volume fraction of 30%. The roughness was less than one-tenth of the roughness of the SPAI composite film. An increase in the BaTiO 3 crystal size from 10.5 to 34.6 nm in the PVDF film at a particle volume fraction of 30% increased the dielectric constant of the film from 20.1 to 31.8. The BaTiO 3 -PVDF composite film attained high dielectric constant that had more than twice the dielectric constant of the BaTiO 3 -SPAI composite film. The dissipation factor of the PVDF composite film was as low as 0.05 at 10 4 Hz.