Fabrication And Investigations Of The High Dielectric Inorganic/Organic Nanocomposites

High dielectric materials with excellent electrical properties have become the driving force of the development of the electronic industry. The miniaturization and high speed of electronic devices have become increasingly dependent on the development of high-dielectric composite material. But disadvantages of low energy density and high dielectric loss of current commercial ferroelectric capacitor impede its further development. The organic/inorganic composite material has many advantages not available in a single material, for example, adjustable devices can be made by changing the proportion of inorganic doping and dielectric constant. In order to increase the dielectric constant of the polymer matrix, the most commonly used method is to introduce the inorganic phase to prepare a two-phase composite structure, such as micron particles, nanoparticles, nanowires, nanorods and the metal particles, etc. The idea is based on a combination of high dielectric inorganic materials and low dielectric loss of polymer to prepare high density energy storage material.In situ polymerization process was used to fabricate composite materials, X-ray diffraction and scanning electron microscopy were to analyze the microscopic structure. Dielectric properties were tested by using Agilent 4294A precision impedance analyzer. The best performance of the polyimide/CCTO nanoparticle composite is with the loading of 16vol%, in which case a dielectric constant of 171, but at the same dielectric loss is high (0.45, 100Hz). In order to reduce dielectric loss, polyimide/CCTO@ Ag particles and polyimide/CCTO nanowire composite films were prepared. The results show that the conductive silver nanoparticles on the outer surface of the CCTO, which greatly reduce the permittivity difference at the interface, thus avoiding the emergence of uneven distribution of electric field disturbances, making the overall performance of material to be improved. Compoties with high aspect ratio CCTO nanowires reach percolation threshold at a low content (1.5vol%), resulting in a high dielectric constant (89) and a low dielectric loss (0.016, lOOHz). For three-phase composite material, the dielectric constant of polyimide/CCTO/surface modified Multi-walled Carbon Nanotube (MWNT-S) reaches a maximum value of 252 with 0.1 vol% loading while dielectric loss is 0.02 (100 Hz). As for the polyimide/CCTO/graphene-phase composite material, its dielectric constant reaches a maximum of 156 with 0.4vol% filler, the dielectric loss is 0.02. This is because the introduction CCTO hinders electron transition between the graphene conductive path, such that the conductivity of the composite material decreases, and thus result in a low dielectric loss.A variety of complex three-dimensional structure of Flex/PZT@Ag composites with high dielectric constant and low loss were made by 3D printing technology. Its dielectric constant dopant content at 18vol% reaches a maximum of 120 (100Hz), dielectric loss is 0.03.3D printing technology breakthrough the shortcomings of traditional techniques and open up a new way for the preparation of materials. On the other hand, self-healing motion sensor were prepared based on the dynamic Diels-Alder (DA) reaction and (1,1'-(methylene di-4,1-phenylene) bismaleimide and 2,2'-(Thiodimethylene)difuran) MT/S-CCTO high dielectric composite film. High dielectric constant (93) and low dielectric loss is obtained with 17 vol% S-CCTO. 82% recovery of capacitance was got after 10th cut-self-repair cycle, this feature can improve the safety of the material and extend its lifetime.