Enhanced magnetoelectric coefficient and interfacial compatibility by constructing a three-phase CFO@BT@PDA/P(VDF-TrFE) core-shell nanocomposite

A ferroelectric ceramic barium titanate (BaTiO₃, BT) layer and an interfacial agent polydopamine (PDA) as the shells are coated on the cobalt ferrite (CoFe₂O₄, CFO) nanoparticles successively to fabricate the interfacial compatibility of this magnetic oxide. Subsequently, the coated nanoparticles are compounded with ferroelectric poly(vinylidene fluoride-trifluoro ethylene) (P(VDF-TrFE)) matrix to obtain the CFO@BT@PDA/(P(VDF-TrFE) magnetoelectric nanocomposite films. We find these nanocomposites with three phases including a CFO magnetic core, a BT piezoelectric shell and the P(VDF-TrFE) piezoelectric matrix show a considerable dielectric permittivity of 85.7 and a maximum polarization of 49.5 μC/cm². Attractively, after poling the saturated magnetization of this film increases from 52.1 emu/g to 61.7 emu/g, corresponding to a significant magnetoelectric effect. Through non self-consistent theory (NSC), the magnetoelectric coupling coefficient (α_{E 33}) of CFO@BT@PDA/(P(VDF-TrFE) film is calculated to reach 150.58 mV/cm·Oe, indicating that this flexible multiferroic film has a prospect of application on energy collector or new information storage devices.