Magnetoelectric coupling in PVDF/Nano NaNbO3/NanoNi composites: Influence of Ni particles aspect ratio.

In this work, three phase magnetoelectric nanocomposites are successfully prepared by solvent casting from α-PVDF. The extrinsic piezoelectric effect is insured by 20 vol% of NaNbO 3 ferroelectric nanoparticles prepared by the hydrothermal process. Nickel is chosen as the magnetic phase. In order to maintain insulation, electrical percolation is avoided by using nickel contents lower than the percolation threshold. Two different morphologies are employed: spherical nanoparticles (NiNPs) and nanochains (NNCs) with an aspect ratio of 80. NNCs are obtained by a polyol process under a magnetic field. Thin films of nanocomposites are processed by hot pressing. The real part of the dielectric permittivity (ε') of composites is governed by Maxwell-Wagner-Sillars polarization at the PVDF/Ni interfaces. An important increase of ε' at low frequency is observed for PVDF/NaNbO 3 /NNCs composites; it favors the magnetoelectric coupling. Piezoelectric properties of composites are dependent upon mechanical modulus so that the most higher d 33 is obtained for PVDF / NaNbO 3 / NiNPs. Magnetoelectric coupling coefficient (α ME) is determined from magnetoelectric intensity. PVDF / NaNbO 3 / NiNPs composites exhibit enhanced magnetoelectric coupling. The a ME coupling coefficient reaches 4.2V/(mOe). The magnetic properties are significantly improved by the NiNPs [ABSTRACT FROM AUTHOR]