Individually free-standing piezoelectric nanotubes-based BaTiO3/CoFe2O4 magnetoelectric thin films

Abstract

In this study, individually free-standing piezoelectric nanotubes-based magnetoelectric thin films were synthesized by complexation of one-dimensional (1D) BaTiO3 as the piezoelectric phase, and CoFe2O4 as the magnetostrictive phase. Particularly, the individually TiO2 free-standing nanotubes were developed onto a Ti substrate via metal anodizing to obtain a high standing stability of 1D piezoelectric structure and a filling volume of magnetostrictive phase, simultaneously for fabrication of magnetoelectric thin films. After BaTiO3 perovskite conversion from the TiO2 nanotubes, an enough volume still remains for sufficient self-filling of CoFe2O4 between the BaTiO3 nanotubes. Finally, BaTiO3/CoFe2O4 magnetoelectric films were found to exhibit a dense structure being suitable for strong magnetostriction-mediated piezoelectric voltages. The structure design, based on individually free-standing nanotubes, would be feasible for flexible magnetoelectric devices such as health monitoring sensors, energy harvesters, and memory devices.