Control of the nanostructure in percolative multiferroic composites on the dielectric loss and magnetism threshold
Control of the nanostructure in percolative multiferroic composites on the dielectric loss and magnetism threshold
复制标题
渗流多铁复合材料中纳米结构对介电损耗和磁阈值的控制
DOI：
10.1039/c5tc01753j
复制
发表时间：
2015-01-01
影响因子：
6.4
通讯作者：
Du, Piyi
中科院分区：
文献类型：
--
作者：
Tang, Yu;Zhang, Yi;Du, Piyi
揭示微结构对多铁性复合材料介电和磁性能的控制对设计高性能复合材料具有重要意义。本文采用射频磁控溅射法制备了BTO/NZFO复合薄膜，其固溶体组成相在20 nm左右。利用XRD、TEM和XPS等测试手段对纳米复合薄膜的晶格常数、晶粒尺寸、本征氧空位、非本征氧空位和非化学计量比缺陷进行了表征。用阻抗分析仪和MPMS分别测试了纳米复合材料的电导率、介电性能和磁性能。在这种多敏感性纳米复合薄膜中，介电常数与柯克帕特里克模型相容，并且介电损耗由高比例的晶界控制，晶界抑制电荷迁移，从而使损耗显著降低。纳米复合薄膜的饱和磁化强度主要受纳米尺寸组成相的晶格变形的影响。纳米复合材料的磁阈值从真实的拓扑磁阈值下移，有利于复合材料同时具有低的介电损耗和高的磁导率。磁性受NZFO颗粒尺寸和纳米粒子间的磁连通控制，表现出一种新的逾渗行为。
Revealing clearly the control of the microstructure on the dielectric and magnetic properties of multiferroic composites is of great importance in designing a composite with high performance. In this paper, BTO/NZFO composite thin films with solid solution constituent phases around 20 nm were prepared by RF magnetron sputtering. The lattice constant, grain size, intrinsic and extrinsic oxygen vacancies and non-stoichiometric defects in the nanocomposite thin film are measured by XRD, TEM and XPS. The conductivity, dielectric properties and magnetic performances of the nanocomposite are measured by an impedance analyzer and MPMS respectively. In this multisusceptible nanocomposite thin film, the permittivity is compatible with the Kirkpatrick model, and the dielectric loss is controlled importantly by the high fraction of grain boundaries which restrains the charge migration and thus makes the loss significantly low. The saturation magnetization of the nanocomposite thin film is influenced mainly by the lattice deformation of the nanosized constituent phases. The magnetic threshold of the nanocomposite shifts downwards from the real topological one, which is profitable for the composite to contribute simultaneously a low dielectric loss and high permeability. The coercivity, which is controlled by the grain size of NZFO and magnetic communication among NZFO nanoparticles, displays a novel percolation behavior.