School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331, China.
Nanoscale. 2018 Jul 5;10(25):11750-11759. doi: 10.1039/c8nr02368a.
Magnetoelectric multiferroic fluids composed of BaTiO3@CoFe2O4 composite nanoparticles dispersed in a highly insulating nonpolar oleic acid/silicone oil mixture have been developed. The effects of the particle volume fraction and a magnetic field, as well as an electric field, on the ferroelectric and magnetic properties, as well as the magnetoelectric coupling effect, have been systematically studied and discussed in this paper. Magnetic characterization shows an approximation to superparamagnetism, and both the remanent magnetization (Mr) and the coercive field (Hc) increase with increases in the volume fraction and applied electric field. Similarly, a superparaelectric state has been observed in the multiferroic fluids, in which both the remanent polarization (Pr) and the coercive field (Ec) are near zero, whereas they increase with increases in the applied magnetic field and volume fraction. High converse and direct magnetoelectric coupling coefficients are estimated to be αH = 8.16 × 10-4 (Oe cm) V-1 and αE = 1.58 × 104 V (cm Oe)-1, respectively. Further analysis indicates that the composite particles can be aligned under an external magnetic/electric field so that their magnetic/electric moments can be parallel to the external field, which in turn results in changes in the magnetization/polarization directions. These results imply that besides magnetoelectric fluids that consist of core/shell-structured nanoparticles, conventional multiferroic fluids based on composite particles may provide an opportunity to gain electrical control of magnetization and vice versa, which implies potential applications.
已开发出由 BaTiO3@CoFe2O4 复合纳米粒子分散在高度绝缘的非极性油酸/硅油混合物中的磁电多铁性流体。本文系统研究和讨论了颗粒体积分数和磁场以及电场对铁电和磁性能以及磁电耦合效应的影响。磁性表征显示出超顺磁性的近似，剩余磁化强度（Mr）和矫顽力（Hc）都随体积分数和外加电场的增加而增加。同样，在多铁性流体中观察到超顺电状态，其中剩余极化强度（Pr）和矫顽力（Ec）均接近零，而随外加磁场和体积分数的增加而增加。估计高的逆磁电耦合系数αH为 8.16×10-4（Oe cm）V-1，直接磁电耦合系数αE为 1.58×104V（cm Oe）-1。进一步的分析表明，复合粒子可以在外磁场/电场下对齐，从而使它们的磁/电矩与外场平行，这反过来又导致磁化/极化方向发生变化。这些结果表明，除了由核/壳结构纳米粒子组成的磁电流体之外，基于复合粒子的常规多铁性流体可能提供电控制磁化和反之亦然的机会，这意味着潜在的应用。
