中文摘要：

利用湿化学还原法制备了银（Ag）颗粒,并用正硅酸乙酯对其进行处理,通过混合和热压工艺制备了正硅酸乙酯改性的银填充聚偏二氟乙烯介电复合材料。研究了正硅酸乙酯水解得到二氧化硅（SiO2）绝缘层对该复合材料介电性能的影响。结果表明：正硅酸乙酯水解在Ag颗粒之间生成的SiO2绝缘层避免了Ag颗粒之间的直接接触,形成了内部电子阻隔层,使复合材料的渗流阈值增大,介质损耗保持较低的值（小于0.08,1kHz,体积分数28%）,电导率为2.85×10-5S/m（1 kHz,体积分数28%）。由于SiO2绝缘层具有一定的厚度（计算值为10 nm）,载流子在金属Ag颗粒间及颗粒与基体间跃迁相对较难,导致了该复合材料具有较低的介电常数值（ε=38.5,1 kHz,体积分数28%）。

英文摘要：

Ag particles were prepared by an aqueous chemical method and modified with TEOS.A dielectric composite with PVDF as matrix and TEOS modified Ag particles as fillers was synthesized by means of mixing and hot-pressing technology.The effect of SiO2 insulating layer generated from hydrolysis of TEOS on the dielectric and electric properties of the composite was studied.SiO2 with amorphous network structure can prevent Ag particles from contacting with each other and act as an internal barrier layer of electrons.As a result,the composite has a higher percolation threshold,a lower loss（0.08） and conductivity（2.85×10-5 S/m） even at a high volume fraction of 28 vol%（1 kHz）.But the SiO2 insulating layer（10 nm in thickness） will restrict transition of charge carriers between Ag particles and PVDF matrix.The dielectric composite possesses a relatively low permittivity of 38.5 at 28 vol%（1 kHz）.