Enhanced multiferroic and magnetoelectric properties of Ni-0.92(Cu0.05Co0.03)Fe2O4/Ba1-xCaxZr0.10Ti0.90O3 lead-free composite films

摘要

The search for lead-free high performance magnetoelectric multiferroic materials at room temperature continues to be stimulated from the perspective of designing environmentally friendly multifunctional devices. In this context, lead-free composite thin films consisting of Ba1-xCaxZr0.10Ti0.90O3 (BCZT, x = 0, 0.10 and 0.15) as the ferroelectric/piezoelectric phase and Ni-0.92(Cu0.05Co0.03)Fe2O4 (NCCFO) as the ferromagnetic/magnetostrictive component have been grown on Pt/TiO2/SiO2/Si substrates via chemical solution spin-coating method. The phase and structural evolutions of two distinct pure phases of as grown NCCFO/BCZT composite films were confirmed using X-ray diffractrometry (XRD) and field emission scanning electron microscopy (FE-SEM). The multiferroic, magneto-dielectric and magnetoelectric properties of the NCCFO/BCZT composite films have been investigated. Moreover, significant enhancement of multiferroic properties and magnetoelectric effect was observed in these composite films when compared to those reported recently for other lead-free BCZT based multiferroic composites. The magnetic studies demonstrate that the NCCFO/Ba0.90Ca0.10Zr0.10Ti0.90O3 (NCCFO/BCZT10) composite film exhibits a large saturation and remnant magnetization of M-s similar to 346.2 emu/cm(3) and M-r similar to 73.5 emu/cm(3) respectively having a coercive field of H-c similar to 73.5 Oe. The NCCFO/BCZT10 composite film also exhibits good ferroelectric properties with saturation polarization P-s similar to 26.7 mu C/cm(2), remnant polarization P-r similar to 8.9 mu C/cm(2) and coercive field E-c similar to 82.7 kV/cm. The observed magneto-dielectric effect is of two orders higher than those reported for other lead-free multiferroic composites. A maximum magnetoelectric voltage coefficient of alpha(ME) similar to 22.4 mVcm(-1) Oe(-1) is obtained for the NCCFO/BCZT10 composite film. The observed results suggest that the NCCFO/BCZT composite films are potential lead-free multiferroic systems at room temperature.