4:45 PM - 5:00 PM
△ [13p-2L-11] Dielectric Properties of Metal / Insulator Composite Capacitors with Boundary Layer Structure
Keywords:Composite material,Dielectric property,Hydrothermal method
To develop metal/insulator composite capacitors with high effective dielectric constant, we focus on a microstructure of boundary layer (BL) capacitors. The titanium metal/barium titanate (Ti/BT) composites consisting of Ti metal grains and BT boundary nanolayers were successfully prepared from the pressed Ti-BT core-shell particle compacts with various thicknesses of the BT shell layers by the hydrothermal method below 230 °C. In this hydrothermal process, the BT polycrystalline shell layers were connected with each other by crystal growth due to the dissolution and reprecipitation mechanism in the barium hydroxide (Ba(OH)2) aqueous solutions. The thickness of the BT boundary layers increases with an increase in the concentration of the Ba(OH)2 reaction solutions used in preparation of the core-shell particles and dominated electrical properties. The effective dielectric constant and loss tangent tend to increase with an decrease in the thickness of BT boundary layers. By adjusting the preparation conditions, the resultant Ti/BT composites exhibit the high effective dielectric constant over 10000 and relatively smaller tangent loss in spite of the high volume fraction of Ti metal, approximately 70-80%. This experimental fact suggests that the individual metal particles were separated and insulated by the insulator-shell nanolayers.