Electric, magnetic, piezoelectric and magnetoelectric studies of phase pure (BiFeO3–NaNbO3)–(P(VDF-TrFE)) nanocomposite films prepared by spin coating

Abstract

(BiFeO₃–NaNbO₃)–(P(VDF-TrFE)) co-polymer thin films were fabricated by spin coating technique and their electric, magnetic, electromechanical and magnetoelectric properties were investigated. In order to get the crystallization ‘β’ phase, the films have been annealed at 138 °C. The structural analysis of the films have been carried out using XRD, SEM, TEM, AFM, confocal Raman spectroscopy and FTIR spectroscopy which confirm the presence of BiFeO₃ and NaNbO₃ phases along with P(VDF-TrFE) crystalline phase. The magnetoelectric coupling measurements at room temperature confirm the multiferroic nature of the composite film with significant magnetoelectric coupling between BiFeO₃, NaNbO₃ and P(VDF-TrFE). The ME measurement gives a maximum coupling coefficient of 2.4 V cm⁻¹ Oe⁻¹ for the ceramic-polymer composite film which is two times higher than that of the ceramic alone. The higher piezoelectricity of the P(VDF-TrFE) (d₃₃ > 20 pC/N) is expected to contribute to the enhancement in the electric and magnetic properties of the composite. The hysteresis loop observed at room temperature confirms the ferromagnetic property of the composite. The ultrahigh dielectric constant for 10 vol% of the ceramic in the polymer matrix with a low loss value (≈1) is a remarkable improvement. The resultant high dielectric permittivity, magnetoelectric coupling and ferromagnetic property at room temperature of these innovative nanocomposites make them particularly attractive for technological applications as storage energy materials.