Work

Microwave dielectric properties and LBS-assisted low-temperature sintering of Ba2CaCo2Si6O17 ceramics

Year: 2026

Type: article

Abstract: The excessively high sintering temperature of silicate microwave dielectric ceramics greatly restricts their practical integration into low-temperature co-fired ceramic (LTCC) modules for 5G and 6G millimeter-wave communication devices. To address this limitation, orthorhombic Ba 2 CaCo 2 Si 6 O 17 (BCCS) ceramics with Cmcm space group were synthesized via the conventional solid-state reaction route. At the optimal sintering temperature of 1090 °C, pure BCCS ceramic achieves favorable microwave dielectric performances: ε ᵣ = 7.7, Q × f = 36,493 GHz and τ f = −33 ×10 −6 °C −1 . The variation in Q × f correlates with lattice energy, grain growth, and densification, while the distortion degree of CaO 6 octahedra presents an inverse correlation with τ f ; these correlations should not be regarded as a complete description of the intrinsic phonon-loss mechanism. The addition of 2% (in mass) LBS glass enabled densification at 800 °C with retained dielectric properties ( ε ᵣ = 4.9, Q × f = 24,891 GHz, τ f = −23.3 ×10 −6 °C −1 ). XRD of the LBS-containing ceramics detected no additional crystalline phase, and no additional crystalline reaction phase was detected after co-firing with Ag at 800 °C. Because only surface EDS was obtained, the Ag result is regarded as a preliminary co-firing compatibility assessment rather than proof of diffusion-free interfacial compatibility. These results identify LBS-assisted BCCS as a promising low-permittivity system for further LTCC-oriented investigation.

Source: Journal of Materiomics

DOI: 10.1016/j.jmat.2026.101327