Improved ferroelectric properties in KBiFe2O5-polymer composite film

Abstract

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.