Microwave dielectric properties of Ba₂CaMg₂Si₆O₁₇-based ceramics for LTCC applications

The crystal structure, phase formation, and microwave properties of Ba₂CaMg₂Si₆O₁₇-based (BCMS) ceramics were systematically analyzed. The BCMS ceramics are classified as belonging to the orthorhombic crystal system with the Cmcm space group. Notably, the BCMS ceramics sintered at 1170 °C exhibited favorable dielectric properties, with a dielectric constant (ε_r) of 7.6, quality factor (Q × f) of 23,574 GHz, and a temperature coefficient of resonance frequency (τ_f) of -66 ppm/°C. Moreover, the introduction of LiF, BaCu(B₂O₅) (BCB), and Li₂O-B₂O₃-SiO₂ (LBS) facilitated the reduction of the sintering temperature in BCMS ceramics. Further analysis revealed that an excessive amount of LiF/BCB modification deteriorated the Q × f values of the ceramics. Additionally, the addition of a small quantity of LBS glass facilitated the densification of the BCMS ceramics without significantly deteriorating their dielectric properties. In particular, the BCMS ceramics with 2 wt% LBS added performed exceptionally well, exhibiting an ε_r of 6.7, Q × f of 21,051 GHz, and a τ_f of − 52 ppm/°C. Considering the chemical compatibility with silver, the BCMS + 2 wt% LBS ceramics are anticipated to be potential candidates for low-temperature co-fired ceramics (LTCC) applications.