Microwave dielectric properties of low-fired (1−x)Mg2Si0.9V0.1O4–xCa0.8Sr0.2TiO3 composite ceramics

• Low-fired 0.91Mg2Si0.9V0.1O4-0.19Ca0.8Sr0.2TiO3-4wt%LiF ceramics are fabricated.
• Eutectic liquid phase Ca2V2O7 and 0.12CaF2/0.28MgF2/0.6LiF were developed.
• Eutectic liquid phase reduced sintering temperature of ceramics to 900 °C.
• The microwave dielectric properties of ceramics were controlled by composition.
• Ceramics with well dielectric properties are suitable for LTCC applications.

The low-fired (1−x)Mg2Si0.9V0.1O4–xCa0.8Sr0.2TiO3 (MSV-CST, 0.15 ≤ x ≤ 0.25) composite ceramics doped with 4 wt% LiF were fabricated by a conventional solid-state route, and their sintering characteristics, microstructures, crystal compositions and microwave dielectric properties were investigated systematically. Eutectic liquid phase Ca2V2O7 and LiF were developed, which lowered the sintering temperature of MSV-CST composite ceramics to 900 °C. The microwave dielectric properties of MSV-CST ceramics were mainly controlled by the CST composition (x). A typical sample of 0.81MSV-0.19CST-4 wt% LiF, which owned well microwave dielectric properties (ɛr = 11, Q × f = 49 000 GHz (at 9.5 GHz), and τf = −7 ppm/°C), were achieved at 900 °C for 4 h. Such sample was compatible with Ag electrodes, suitable for the low-temperature co-fired ceramics (LTCC) applications.