Microwave Dielectric Properties of Low-Fired Ba_5Nb_4O_(15)

摘要

The effect of B_2O_3 on the sintering temperature and microwave dielectric properties of Ba_5Nb_4O_(15) has been investigated using X-ray powder diffraction, scanning electron microscopy, and a network analyzer. Interactions between Ba_5Nb_4O_(15) and B_2O_3 led to formation of second phases, BaNb_2O_6 and BaB_2O_4. The addition of B_2O_3 to Ba_5Nb_4O_(15) resulted in lowering the sintering temperature from 1400° to 925℃. Low-fired Ba_5Nb_4O_(15) could be interpreted by measuring changes in the quality factor (Q x f), the relative dielectric constant (ε_r), and the temperature coefficient of resonant frequency (T_f) as a function of B_2O_3 additions. More importantly, the formation of BaNb_2O_6 provided temperature compensation. The microwave dielectric properties of low-fired Ba_5Nb_4O_(15) had good dielectric properties: Q x f = 18700 GHz, ε_r = 39, and T_f = 0 ppm/℃.