Temperature-stable BaAl2Si2O8–Ba5Si8O21-based low-permittivity microwave dielectric ceramics for LTCC applications

Abstract Low-temperature sintering (1− x )BaAl 2 Si 2 O 8 – x Ba 5 Si 8 O 21 microwave dielectric ceramics were prepared by solid-state reaction. The effects of LiF (1 wt%) on the sintering behaviour, phase composition and microwave dielectric properties of (1− x )BaAl 2 Si 2 O 8 – x Ba 5 Si 8 O 21 ( x = 0, 0.3 and 1.0) were investigated. The addition of 1 wt% LiF lowers sintering temperature to 900 °C ( x = 0) and 750 °C ( x = 0.3 and 1.0) without changing phase composition and apparently degrading microwave dielectric properties. 0.7BaAl 2 Si 2 O 8 –0.3Ba 5 Si 8 O 21 +1 wt% LiF was well-sintered at 750 °C and showed good microwave dielectric properties with e r = 7.63, Q × f = 12,410 GHz and τ f = −1.2 ppm/°C. This composite exhibited good chemical compatibility with Ag electrodes, making it a promising candidate for practical applications of low-temperature co-fired ceramics.