Rapid densification mechanism of SrZn0.8Mg0.2Si3O8 microwave dielectric ceramics

SrZn 0.8 Mg 0.2 Si 3 O 8 ceramics capable of rapid densification under atmospheric pressure, while maintaining excellent microwave dielectric properties were investigated. In-situ scanning electron microscopy and high-resolution transmission electron microscopy confirm the formation of a liquid phase during sintering and clarify its chemical composition. Rapid densification originates from intrinsic generation of this liquid phase in SrZn 0.8 Mg 0.2 Si 3 O 8 during the sintering process. Because the liquid phase is produced internally, most of it spontaneously crystallizes into the parent phase during cooling. Therefore, the final microstructure consists predominantly of the SrZn 0.8 Mg 0.2 Si 3 O 8 phase with only a small residual amorphous phase. SrZn 0.8 Mg 0.2 Si 3 O 8 ceramics thus exhibit excellent microwave dielectric properties ( ε r = 6.07 ± 0.02, Q×f = 69,350 ± 650 GHz ( f = 16.37 GHz), τ f = −27.6 ± 1.4×10 –6 °C –1 , holding time( H.T. ) = 1 min), which are superior to those of conventional composite ceramics that rely on added low-melting-point oxides to induce liquid-phase sintering. In addition, rapid densification enables grain refinement while maintaining high relative density. This microstructural feature improves mechanical strength and electrical breakdown strength and suppresses long range ionic diffusion during heterogeneous cofiring integration.