Low temperature sintering of BaCu(B2O5)-added BaO–Re2O3–TiO2 (Re = Sm, Nd) ceramics

The sintering temperature of BaSm2Ti4O12 (BST) and BaNd2Ti5O14 (BNT) ceramics was approximately 1350 °C and decreased to 875 °C with the addition of BaCu(B2O5) (BCB) ceramic powder. The presence of the liquid phase was responsible for the decrease of the sintering temperature. The liquid phase is considered to have a composition similar to the BaO-deficient BCB. The bulk density and dielectric constant (ɛr) of the specimens increased and reached saturated value with increasing BCB content. The Q-value initially increased with the addition of BCB, but decreased considerably when a large amount of BCB was added, because of the presence of the liquid phase. Good microwave dielectric properties of Q × f = 4500 GHz, ɛr = 60 and τf = −30 ppm/°C were obtained for the 16.0 mol% BCB-added BST ceramics sintered at 875 °C for 2 h. Moreover, the BST and BNT ceramics containing BCB show good compatibility with silver metal.