Low-temperature sintering and microwave dielectric properties of BaO·(Nd1−xBix)2O3·4TiO2 by the glass additions

The system BaO·(Nd1−xBix)2O3·4TiO2 solid solution containing lithium borosilicate glass were prepared and examined as a low-temperature co-fired ceramics (LTCC). The sintering properties of the low-temperature sintered BaO·(Nd1−xBix)2O3·4TiO2 with glass frit were investigated using dilatometer, SEM and TEM. The microwave dielectric properties were measured using a network analyzer. The addition of glass to BaO·(Nd1−xBix)2O3·4TiO2 significantly lowered the sintering temperature to ∼900 °C in comparison to ∼1300 °C for samples without glass. The formation of liquid phase present in the low temperature sintered sample was confirmed using TEM. It was found that thermal properties of the added lithium borosilicate glass dominated the sintering properties of BaO·(Nd1−xBix)2O3·4TiO2 including shrinkage onset temperature and shrinkage rate. The sample of BaO·(Nd0.8Bi0.2)2O3·4TiO2 with 10 wt.% glass sintered at 900 °C exhibited a quality factor (Q×f) of 2200 GHz, a εr of 68, and a τf of 55 ppm/°C.