Low-temperature sintering and dielectric properties of high-permittivity microwave (Ca, Nd)TiO3 ceramics

The effect of H₃BO₃-CuO-Li₂CO₃ combined additives on the sintering temperature, microstructure and microwave dielectric properties of (Ca_0.61Nd_0.26) (Ti_0.98Sn_0.02)O₃ (CNTS) ceramics was investigated. The H₃BO₃-CuO-Li₂CO₃ combined additives lowered the sintering temperature of CNTS ceramics effectively from 1300 to 950 °C. This may be due to the interim liquid-phase of Li₂O-CuO-B₂O₃, which were formed in the sintering process. (Li_0.5Nd_0.5)TiO₃ (LNT) demonstrated an effective compensation in τ_f value of the low-fired CNTS ceramics. The 0.4CNTS-0.6LNT ceramics with 5 wt% (H₃BO₃-CuO)-0.5 wt% Li₂CO₃ sintered at 900 °C for 2 h shows excellent dielectric properties: ?_r = 90.6, Q × f = 3400 GHz, and τ_f = 9 ppm/°C. Also, the LTCC material is compatible with Ag electrode.