Preparation and characterization of Ag-doped BaTiO3 based X7R ceramics

Ag-doped BaTiO₃ based X7R (temperature coefficient of capacitance within the range of ±15% between −55 and +125 °C) ceramics with different amounts of silver (0.0-20.0 mol%) were prepared in this paper. The X-ray diffraction analysis indicated that no phases other than BaTiO₃ and silver were observed in the ceramics. The energy dispersive X-ray spectroscopy analysis showed that the silver particles presented homogeneous distribution in the BaTiO₃ ceramics. The dielectric properties of Ag-doped ceramics were investigated. A small amount of silver (<0.5 mol%) and a large amount of silver (>2.0 mol%) could both improve the sintered density and permittivity, but more content of silver (0.5-2.0 mol%) would decrease the relative density and permittivity. Specially, the temperature coefficient of capacitors of the ceramics doped with 20 mol% silver still met the X7R characteristics, and the room temperature permittivity of the ceramics was 6823, which was the highest dielectric constant in the BaTiO₃ based X7R ceramics.