Phase evolution, microstructure and microwave dielectric properties of 2Li₂O-AO-3WO₃ (A=Mg, Zn) composite ceramics

Low-firing microwave dielectric ceramics with compositions of 2Li₂O-AO-3WO₃ (A=Mg, Zn) were prepared by the solid state reaction method. The sintering behavior, microstructure and microwave dielectric properties of ceramics were investigated. The bulk density, quality factor (Q × f) and relative permittivity (ε _r ) of 2Li₂O-AO-3WO₃ (A=Mg, Zn) ceramics firstly increased, reached a max value and then decreased with increasing the sintering temperature. 2Li₂O-MgO-3WO₃ ceramics shown a low sintering temperature (~700 °C) and good microwave dielectric properties with Q × f value of 23,582 GHz, ε _r of 5.89 and τ _f value of −78 ppm/°C. 2Li₂O-ZnO-3WO₃ ceramics sintered at 675 °C also presented excellent microwave dielectric properties with Q × f = 21,706 GHz, ε _r  = 6.76 and τ _f  = −94 ppm/°C. Most importantly, 2Li₂O-AO-3WO₃ (A=Mg, Zn) ceramics illustrated good chemical compatiblity with silver powders, which indicate that they can be used to LTCC multilayer devices.