抄録
A series of metal/insulator composite capacitors with embedded metal particles in an insulator layer has attracted attention because of their high effective dielectric constant. We tried to improve dielectric breakdown strength of these metal/insulator composite capacitors by covering individual metal particles with insulator ceramics nanolayers. Micrometer-sized Ti metal particles were homogeneously covered by BaTiO3 (BT) nanolayers with different thicknesses by the hydrothermal method, and these Ti (core)-BT (shell) particles were used for the fabrication of Ti/BT composites. The dielectric constant of the resultant Ti/BT composite capacitors with a Ti metal content of approximately 22 vol% is ranged around 800-1000, and the dielectric breakdown strength (Eb) is slightly enhanced by using the Ti-BT core-shell particles as compared to the Ti/BT composite prepared by using uncoated Ti metal particles. However, the Eb of the Ti/BT composites is independent of the BT shell-layer thickness of the core-shell particles. It can be considered that the BT shell layers are helpful for an enhancement in homogeneity of the metal-particle distribution, but cannot suppress the current leakage at high voltage due possibly to their low-crystallinity and/or porous structure.
