A new temperature stable microwave dielectric ceramics: ZnTiNb_2O_8 sintered at low temperatures

摘要

The phases, microstructure and microwave dielectric properties of ZnTiNb_2O_8-xTiO_2 composite ceramics with different weight percentages of BaCu(B_2O_5) additive prepared by solid-state reaction method have been investigated using the X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results showed that the microwave dielectric properties were strongly dependent on densification, grain sizes and crystalline phases. The sintering temperature of ZnTiNb_2O_8 ceramics was reduced from 1250°C to 950°C by doping BaCu(B_2O_5) additive and the temperature coefficient of resonant frequency (τ_f) was adjusted from negative value of -52ppm/°C to Oppm/°C by incorporating TiO_2. Addition of 2 wt% BaCu(B_2O_5) in ZnTiNb2Os-xTiO_2 (x = 0.8) ceramics sintered at 950 °C showed excellent dielectric properties of ε_r = 38.89, Q x f= 14,500 GHz (f=4.715GHz) and r/=0ppm/°C, which represented very promising candidates as LTCC dielectrics for LTCC applications.