Silver cofirable Bi1.5Zn0.92Nb1.5O6.92 microwave ceramics containing CuO-based dopants

Bi2O3-ZnO-Nb2O5 system has emerged as a good low sintering (-1050 deg C) microwave material because it exhibits high dielectric constant and low temperature coefficient of resonance frequency (tau(f)). We have lowered the sintering temperature of Bi1.5Zn0.92Nb1.5O6.92 (BZN) below 900 deg C by using 3wt.% of CuO-based dopants, such as 0.21BaCO3-0.79CuO (BC) and 0.81MoO3-0.19CuO (MC). The doped BZN exhibits high microwave dielectric constant at 2.3 GHz (k-120). The interfacial behavior between BZN and silver was investigated by using X-ray diffractometer, scanning electronic microscope, and electronic probe microanalyzer. The extent of silver migration of MC and BC dopants is reduced at least by one order of magnitude as compared with V2O5 dopant when the samples was prepared at 900 deg C for 4h. Thus, CuO-based dopants can replace V2O5 to lower the sintering temperature of BZN and to be cofired with silver.