Effects of silver addition on microstructure and electrical properties of barium titanate ceramics

Barium titanate–silver composites were prepared by using a solid state reaction process with silver contents ranging from 0 mol% to 20 mol%. XRD results and Raman spectra indicated that there was no phase other than BaTiO3 and Ag in the ceramics and tetragonality of barium titanate reduced with increasing Ag content. SEM images illustrated that Ag influenced densification and microstructure of BaTiO3 ceramics. Besides, addition of Ag led to increase in dielectric permittivity and broadening of ferroelectric–paraelectric phase transition peak. Also addition of Ag had effects on dielectric loss and dc conductivity. Dielectric and conductivity properties as a function of Ag volume fraction were explained by the percolation theory.

► Silver does not react with BaTiO3 during sintering, while it influences densification and microstructure of BaTiO3 ceramics.
► All these factors, such as density, microstructure and percolation threshold effects, have effects on dielectric an conductivity properties of barium titanate–silver composites.
► Low concentrations of Ag in BaTiO3 ceramics led to increase in dielectric permittivity and decrease in dielectric loss and conductivity, so it can be a candidate for application in MLCC materials.