Improved ferroelectric properties in KBiFe2O5-polymer composite film

Composite films of KBiFe₂O₅ and PVA were prepared with a varied weight percentage of PVA by spin coating method on platinised silicon wafer. The composite films were characterised for dielectric and ferroelectric properties in comparison to pure KBiFe₂O₅thick film. The frequency dependent permittivity measurement indicated a higher contribution of space charge/interfacial polarization in KBiFe₂O₅ thick film than that in the KBiFe₂O₅ -PVA composite films. The ferroelectric properties in composite films were enhanced due to the reduction in leakage current and they showed well saturated polarization hysteresis loops. The remanent polarization value in KBiFe₂O₅ -PVA composite film (Pr?=?3.7?μC/cm²) was found to be 2.5 times higher than that of the pure KBiFe₂O₅ film (Pr?=?1.45?μC/cm²) and with the increase in PVA percentage, the remanent polarization values also increased. The space charge dominated conduction in pure KBiFe₂O₅ became transformed to field assisted ionic conduction in the KBiFe₂O₅ composite films. The polymeric matrix in KBiFe₂O₅ composites helped in reducing the leakage current of pure KBiFe₂O₅ by four orders of magnitude and further reduced with the increase in the PVA content in the composite. The composite films showed fatigue free polarization even after 10⁸ switching cycles whereas the polarization degradation in KBiFe₂O₅ film was 30% around 10⁸switching cycles.