Temperature-stable BaAl2Si2O8–CaSnSiO5 microwave dielectric ceramics

In the present study, (1 − x )BaAl 2 Si 2 O 8 − x CaSnSiO 5 − y wt.% LiF microwave dielectric ceramics were prepared through the traditional solid-state sintering at 950−1395°C for 5 h. The BaAl 2 Si 2 O 8 phase could coexist with the CaSnSiO 5 phase at (1 − x )BaAl 2 Si 2 O 8 − x CaSnSiO 5 (.2 ≤ x ≤ .6) ceramics, and no other secondary phase was observed. The CaSnSiO 5 , as a τ f regulator, adjusted the negative τ f value of BaAl 2 Si 2 O 8 to near zero. Excellent microwave dielectric properties ( ε r = 8.1, Q × f = 37 560 GHz, and τ f = −1.5 ppm/°C) were obtained from the 0.6BaAl 2 Si 2 O 8 −0.4CaSnSiO 5 ceramic. The sintering temperature of 0.6BaAl 2 Si 2 O 8 −0.4CaSnSiO 5 ceramic decreased from 1375°C to 950°C by introducing 2 wt.% LiF. The 0.6BaAl 2 Si 2 O 8 −0.4CaSnSiO 5 −2 wt% LiF ceramic exhibited remarkable microwave dielectric properties ( ε r = 7.6, Q × f = 17 420 GHz, and τ f = −12.2 ppm/°C) and could be applied to the low-temperature co-fired ceramic (LTCC) field.