A new microwave dielectric ceramic for LTCC applications

A new low-sintering temperature microwave dielectric ceramic, the Li ₂TiO₃ solid solution, was found and investigated in the Li₂O-Nb₂O₅-TiO₂ system. The compound with the composition of Li_2.081Ti_0.676Nb _0.243O₃ crystallizes as a monoclinic structure. This new microwave dielectric ceramic shows a relatively low permittivity (∼20), high Q × f values up to 50000 (7.8 GHz), and near-zero temperature coefficients (13 ppm/°C), which were obtained via sintering at 1100°C. The addition of ≤ 2 wt% B₂O₃ was very effective in lowering the sintering temperature (T_s), and dense ceramics could be obtained at T_s ≤ 900°C. The addition of B₂O ₃ does not induce apparent degradation in the microwave properties but lowers the τ_f value to near zero. It is obvious that the ceramics could be promising candidates for multilayer low-temperature co-fired ceramics applications.