铁电-介电复合物在移相器和相控阵天线等方面应用前景广阔，但其调谐率随铁电材料含量减少(介电常数降低)而明显降低，严重影响其应用。近来发现了部分铁电-介电复合物中调谐率随铁电材料含量减少而增加的"反常现象"，但其增加机制不明。本项目拟针对这一有利的"反常增加现象"，采用放电等离子体烧结技术制备钛酸锶钡基铁电-介电复合物，探明复合效应对调谐性能的影响机制；与此同时，选择有机铁电材料聚偏氟乙烯-三氟乙烯共聚物与无机介电材料进行低温复合，以便完全消除掺杂效应，揭示介电材料对复合物的介电性能和结构的影响规律。在此基础上，探索复合物的化学组成-微结构-介电性能间的关系及介电常数、介电损耗和调谐率间的制约规律，并采用COMSOL MULTIPHYSICS软件模拟介电材料对复合物介电性能的影响。通过实验与理论相结合，探明调谐率反常增加的机制，为克服调谐率下降难题提供解决方案，获得具有自主知识产权的新材料。

Ferroelectric-dielectric composites have potential applications for tunable microwave device such as phase shifters and phased array antennas. However, with the increase of ferroelectrics content (the decrease of dielectric constant), the tunability decreases obviously, so their applications were restricted. Recently, an "anomalous phenomenon" in some ferroelectric-dielectric composites were observed: with the decrease of ferroelectric content, the tunability increases, but it is unclear what the mechanism is. To understand this useful "anomalous increase phenomenon", barium strontium titanate (BST) based ferroelectric-dielectric composites will be prepared by spark plasma sintering (SPS) technology, the influence mechanism of composite effect on the tunable properties will be explored; At the same time, organic ferroelectric materials poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) will be chosen to form composites with inorganic dielectric materials at low temperature, so that doping effect can be eliminated completely, the effects of dielectric materials on the structures and properties of composites will be studied. On the basis of the above works, the relationship of chemical composition-microstructure-dielectric properties and the restricting law of permittivity, loss tangent and tunability will be explored. The effect of linear dielectrics on the dielectric properties of composites will be simulated using COMSOL MULTIPHYSICS. Through the combination of experiment and theory, the mechanism of anomalous increase of the tunability will be proved, solutions to the difficult problem of the decrease of tunability will be provided and new materials with independent intellectual property rights will be obtained.