Ferroelectric and pyroelectric properties of novel lead-free polyvinylidenefluoride-trifluoroethylene–Bi0.5Na0.5TiO3 nanocomposite thin films for sensing applications

Abstract

Novel ferroelectric nanocomposite films with bismuth sodium titanate, Bi0.5Na0.5TiO3 (BNT), particles as fillers and polyvinylidenefluoride-trifluoroethylene, P(VDF-TrFE), copolymer as the matrix were prepared. The sol–gel method was used to synthesize the BNT nanopowder and spin coating was used to fabricate the nanocomposite films. The volume fraction of the BNT (∅) was in the range of 0.1–0.3. The structural, dielectric, pyroelectric, and ferroelectric properties of the samples were extensively investigated. Theoretical models, including Maxwell, Furukawa, Clausius–Mossotti, and effective medium theory (EMT), were employed to describe the effective dielectric permittivity of the composites. It is shown that the incorporation of BNT into the copolymer as a composite film significantly enhances the pyroelectric and ferroelectric properties. The P(VDF-TrFE)–BNT nanocomposite film with ∅=0.2 exhibits an exceptionally high remanent polarization of 115mC/m2 and pyroelectric coefficient of 50µC/m2K1. The figure of merit for detectivity FD is found to increase from 52 to 75µC/m2K1. The enhanced pyroelectric and ferroelectric properties obtained from this novel composite thin film strongly indicate the potential to apply this lead-free material as a thermal/infrared detector, energy storage, and micro-electromechanical system.