Giant permittivity of a bismuth zinc niobate-silver composite

Abstract

Bismuth zinc niobate-Silver (BZN-Ag) composites were prepared by the solid-state ceramic route. The sintering temperature of BZN-Ag composites was lowered to 850°C/2 h. The structure and surface morphology of the composites were investigated using X-ray diffraction and optical microscope. The dielectric and conducting properties of the composites were systematically investigated with the volume fraction of silver in the frequency range from 1 KHz to 1 MHz. The dielectric constant of the composite increases with the silver content and is in good agreement with the power law below the percolation limit. Addition of 0.14 volume fraction of silver increases the dielectric constant of BZN+2 wt% B2O3 from 150 to 2350 at 1MHz. However, 15 volume percentage of silver loading results in a large permittivity of (Epsilon r)~10 to the power of 5 with a low dielectric loss (tan delta ~ 10 to the power of -2) at 1 MHz. Subsequent increase in silver loading decreases the dielectric constant. The BZN-B2O3-Ag composite with large permittivity may find applications in electromechanical and tunable devices.