Wang Liang, Bai Yang, Lu Xuefei, Cao Jiang-Li, Qiao Li-Jie
Key Laboratory of Environmental Fracture (Ministry of Education), University of Science and Technology Beijing, Beijing 100083, China.
Sci Rep. 2015 Jan 5;5:7580. doi: 10.1038/srep07580.
High permeability and high permittivity are hard to be achieved simultaneously, either in single-phased materials or in composite materials, such as ferrite-ferroelectric ceramic composites and ferrite-metal percolative composites. In this work, ultra-low percolation threshold is achieved in NiZnCu ferrite-Ag cofired ceramics, which endows the composite with both high permeability and high permittivity by minimizing the negative effect of nonmagnetic conductive fillers on magnetic properties. The percolation threshold is controlled by the temperature matching between ferrite densification and Ag melting. A thin and long percolative net forms between large ferrite grains under a proper cofiring process, which brings a low percolation threshold of 1.21vol%, more than one order of magnitude lower than the theoretical value of 16vol%. Near the ultra-low threshold, the composite exhibits a high permeability of 585 and a high permittivity of 78.
无论是在单相材料还是在复合材料中，如铁氧体 - 铁电陶瓷复合材料和铁氧体 - 金属渗流复合材料，都很难同时实现高磁导率和高介电常数。在这项工作中，在NiZnCu铁氧体 - 银共烧陶瓷中实现了超低渗流阈值，通过最小化非磁性导电填料对磁性能的负面影响，赋予了该复合材料高磁导率和高介电常数。渗流阈值由铁氧体致密化和银熔化之间的温度匹配来控制。在适当的共烧过程下，在大铁氧体晶粒之间形成了细长的渗流网络，这带来了1.21vol%的低渗流阈值，比理论值16vol%低一个多数量级。在接近超低阈值时，该复合材料表现出585的高磁导率和78的高介电常数。
