高介电无机/有机复合材料的研究

【作者】 党智敏；

【导师】 南策文；

【作者基本信息】 清华大学 ， 材料学， 2003， 博士

【摘要】 将两种或两种以上的单组分材料进行复合,利用各组分材料的优势可以制备出新型的具有特殊性能的复合材料。在当今新材料的研制和生产过程中,最普遍采用的是颗粒填充聚合物的复合材料,这主要是因为这种复合材料的功能性优越,并且可以满足批量生产过程中的高效率、低成本的要求。例如,高介电常数的柔性聚合物基电介质复合材料在电子工业领域可能有广泛的应用前景,它可以被用来制作具有任意形状的多层片式电容器,因此提高电介质材料的介电常数具有非常重要的意义。本工作研究了以聚偏氟乙烯(PVDF)和低密度聚乙烯(LDPE)两种柔性聚合物为基体,以形状和性质各异的无机物作为填料制备的复合材料的介电性能。利用溶胶-凝胶法以及后续处理制备了锂钛共掺杂的氧化镍(LTNO)、锂单独掺杂的氧化镍(LNO),利用化学沉淀法制备了纳米尺寸氧化锌(n-ZnO),对它们分别与聚合物基体形成的复合材料的介电行为进行了研究。结果表明,尽管复合材料的介电常数得到了一定的提高,但对于不同性质的导电或半导性填料而言,材料发生渗流效应的临界值有所不同,材料的介电常数也不同,这些具有高介电常数的电介质材料有望用作柔性多层片式电容器的介质材料。导电或半导性填料的电导率、形状以及结构等对复合材料的介电常数有重要的影响。以导电组分和钛酸钡(BT)组分共同作为填料与PVDF 混合得到的三相复合材料的介电常数最大,这是由于混合效应和渗流效应共同影响的结果。要得到性能优异的电介质复合材料,应合理地选择适当的聚合物基体、无机填料、复合材料的制备工艺以及工艺的参数等。更多还原

【Abstract】 By integrating two or more materials with complementary properties, newcomposite materials offer the potential to have performance far beyond those of theconstituent materials. There is currently great interest in the technological propertiesof particle-filled polymers, because it is primarily a very efficient in the function andcost-effective process for mass production. For example, the flexibility compositeswith a high dielectric constant have a great future in the electronic industry field. Thecomposites may be used to prepare a shape-bend mutilayer chip capacitors. Therefore,it is very significant for improving the dielectric constant of the composites.The dielectric properties of the composites were studied, which composites weremade of polymer matrix, such as PVDF and LDPE, and inorganic fillers with adifferent shapes and properties. LTNO and LNO fillers were prepared using a sol-gelmethod and other process. Nanoscale ZnO was also prepared by means of aco-precipitation. The dielectric behaviors of the composites with these fillers werestudied. The results show that the composites studied have a high dielectric constant.However, the dielectric constant and the percolation threshold of the composites aredifferent due to the effect of the conductors and semiconductors with differentproperties. The new composites studied here with high dielectric constant may befabricated the mutilayer chip capacitors. The conductivity, shape and microstructureof the fillers have an important effect on the dielectric constant of the composites. Thedielectric constants are very high in three phase composites, which are a (conductor+BT) and PVDF. The high dielectric constant can be explained by means of themixture and percolation effect theories. The composites with an excellent propertycan be tailored by choosing a suitable polymer matrix, inorganic fillers, mixtureprocessing and some important parameters in production.更多还原