Annealing heating rate dependence of microstructure and multiferroic properties in Bi4Ti2.9Fe0.1O12/CoFe2O4 layered magnetoelectric composite films prepared by chemical solution deposition method

Lead-free magnetoelectric composite films of CoFe2O4 (CFO) and Bi4Ti2.9Fe0.1O12 (BTF) were prepared on the LaNiO3-coated Si substrate by chemical solution deposition. Though the CFO layer randomly grows on the LaNiO3 layer, the oriented growth of the BTF layer can be regulated by rapid annealing treatment. The results indicated that the annealing heating rate significantly affects the c-axis orientation of the BTF layer, thereby resulting in obvious changes in microstructure, leakage behavior, dielectricity and ferroelectricity of the BTF/CFO films. The BTF/CFO film prepared at the heating rate of 40 degrees C/s presents the most compact structure, minimum leakage current, maximum dielectric constant and the highest residual polarization of 28.8 mu C/cm(2). Moreover, the excellent magnetoelectric coupling performance along with the highest magnetoelectric coupling voltage coefficient alpha(E) of 20.1 V/cm.Oe can be achieved in these conditions.