The effect of BaTiO 3 addition on the dielectric constant of Si 3 N 4 ceramics

Si 3 N 4 ceramics with different BaTiO 3 contents have been fabricated by pressureless sintering in a N 2 atmosphere at 1680°C for 2 h. Al 2 O 3 and Nd 2 O 3 were used as sintering additives to promote the densification of Si 3 N 4 ceramics. The effect of BaTiO 3 addition on the densification, mechanical properties, phase compositions, microstructure, and dielectric properties of Si 3 N 4 ceramics was investigated. The relative density and flexural strength of Si 3 N 4 ceramics increased with the addition of BaTiO 3 up to 15 wt% and then decreased, while the dielectric constant increased continuously as the BaTiO 3 contents increased. The dielectric constant of Si 3 N 4 ceramics can be tailored in the range from 8.42 to 12.96 by the addition of 5 wt%‐20 wt% BaTiO 3 . Meanwhile, these Si 3 N 4 ceramics all had flexural strength higher than 500 MPa.