Tian Wei, Xiao Bin, Chen Zuhuang, Tang Yu, Ma Ning, Wang Zongrong, Du Piyi
State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University Hangzhou 310027 China
Department of Materials Science and Engineering, Shenzhen Engineering Research Center for Novel Electronic Information Materials and Devices, Southern University of Science and Technology Shenzhen 518055 China.
RSC Adv. 2019 Sep 27;9(53):30641-30649. doi: 10.1039/c9ra05675k. eCollection 2019 Sep 26.
The drastic change of properties near the percolation threshold usually limits the practical applications of percolative composite materials. In this work, a tri-phase system, a BaTiO (BTO)/NiZnFeO (NZFO)/BaFeO (BFO) ceramic composite, is proposed and investigated in detail. The BFO phase was formed during a hybrid process of sol-gel and self-combustion methods. The content of the BFO phase could be tuned conveniently by controlling the preparation conditions. The as-prepared BTO/NZFO/BFO tri-phase composite exhibited unprecedented stable dielectric properties that were distinct from those of conventional percolative composites above the percolation threshold due to the existence of a third phase. When the volume fraction of the NZFO phase exceeds 55%, the electrical conductivity and effective permittivity of the composite remain at a stable value of about 10 S cm and 10 000, respectively, which is almost independent of the composition. Such behavior is the result of the synergistic control effect of the percolation effect and specific phase composition in the system. It is evident that the stability of the dielectric properties of the composite is chiefly contributed by the introduction of the BFO phase. Meanwhile, the composite exhibited a relatively high permeability of ∼17 with 90% NZFO loading, and its saturated magnetization is larger than 73 emu g, approximately 95% of the pure NZFO phase. The finding of our BTO/NZFO/BFO tri-phase ceramic composite with stable giant permittivity and extremely high permeability paves a new way to solve the difficulty of property instability above the percolation threshold in the utilization of percolative materials.
渗流阈值附近性能的急剧变化通常限制了渗流复合材料的实际应用。在这项工作中，提出并详细研究了一种三相体系，即BaTiO（BTO）/NiZnFeO（NZFO）/BaFeO（BFO）陶瓷复合材料。BFO相是在溶胶-凝胶和自燃烧法的混合过程中形成的。通过控制制备条件可以方便地调节BFO相的含量。所制备的BTO/NZFO/BFO三相复合材料表现出前所未有的稳定介电性能，由于第三相的存在，其与传统渗流复合材料在渗流阈值以上的性能不同。当NZFO相的体积分数超过55%时，复合材料的电导率和有效介电常数分别保持在约10 S/cm和10000的稳定值，几乎与组成无关。这种行为是系统中渗流效应和特定相组成协同控制作用的结果。显然，复合材料介电性能的稳定性主要归因于BFO相的引入。同时，该复合材料在NZFO负载量为90%时表现出相对较高的磁导率~17，其饱和磁化强度大于73 emu/g，约为纯NZFO相的95%。我们发现的具有稳定巨介电常数和极高磁导率的BTO/NZFO/BFO三相陶瓷复合材料为解决渗流材料在渗流阈值以上性能不稳定的难题开辟了一条新途径。
