Effect of Cu Content on Dielectric Properties of BaTiO_3/Cu Composite Ceramics

The BaTiO3/Cu composite ceramics doped with Cu in the content range of 0-30 wt% were prepared by the solid-state reaction.The microstructure,percolation threshold and dielectric properties of ceramics were inves-tigated.The results show that the resistivity of BaTiO3/Cu composite ceramic increases with Cu content decreasing and the relationship between them has a non-linear downward trend at the percolation threshold(x=25wt%),then the composite is gradually changing from insulator into conductor.The value of er of BaTiO3/Cu composites is raised with the increase of Cu content,and the maximal value is about 9000 at 1 kHz at room temperature as Cu content of 30wt%.The dielectric loss of BaTiO3/Cu composites increases with the increasing Cu doping,but then decreased with the increasing frequency,which is due to the reducing of the amount of space charge.The tempera-ture coefficient is less than 5% in the temperature range from 25℃ to 115℃,and the dielectric constant is provided with high temperature stability.