Abstract

For the aim of low-temperature co-fired ceramic microwave components, sintering behavior and microwave properties (dielectric constant varepsilon_r, quality factor Q, and temperature coefficient of resonant frequency tau_f) are investigated in Bi_18O(Ca_0.725Zn_0.275)_8Nb_12O_65 [BCZN] ceramics with addition of V_2O_5. The specimens are prepared by conventional ceramic processing technique. As the main result, it is demonstrated that the additives (V_2O_5) show the effect of lowering of sintering temperature and improvement of microwave properties at the optimum additive content. The addition of 0.25 wt% V_2O_5 lowers the sintering temperature to 890°C utilizing liquidphase sintering and show the microwave dielectric properties (dielectric constant varepsilon_r = 75, quality factor Qtimesf = 572 GHz, temperature coefficient of resonance frequency tau_f;=;-10;ppm/°C). The estimated microwave dielectric properties with V_2O_5 addition (increase of varepsilon_r, decrease of Qtimesf, shift of tau_f to negative values) can be explained by the observed microstrucure (sintered density, abnormal grain structure) and possibly high-permittivity Bi_18Zn_8Nb_12O_65 (BZN) phase determined by X-ray diffraction.

• Keywords: Microwave dielectrics;Bismuth-based dielectrics;Vanadium oxide;Low-temperature sintering;