The effect of glass additives on the microwave dielectric properties of Ba(Mg 1/3Ta 2/3)O 3 ceramics

Abstract

The effect of glass additives on the densification, phase evolution, microstructure and microwave dielectric properties of Ba(Mg 1/3Ta 2/3)O 3 (BMT) was investigated. Different weight percentages of quenched glass such as B 2O 3, SiO 2, B 2O 3–SiO 2, ZnO–B 2O 3, 5ZnO–2B 2O 3, Al 2O 3–SiO 2, Na 2O–2B 2O 3·10H 2O, BaO–B 2O 3–SiO 2, MgO–B 2O 3–SiO 2, PbO–B 2O 3–SiO 2, ZnO–B 2O 3–SiO 2 and 2MgO–Al 2O 3–5SiO 2 were added to calcined BMT precursor. The sintering temperature of the glass-added BMT samples were lowered down to 1300 °C compared to solid-state sintering where the temperature was 1650 °C. The formation of high temperature satellite phases such as Ba 5Ta 4O 15 and Ba 7Ta 6O 22 were found to be suppressed by the glass addition. Addition of glass systems such as B 2O 3, ZnO–B 2O 3, 5ZnO–2B 2O 3 and ZnO–B 2O 3–SiO 2 improved the densification and microwave dielectric properties. Other glasses were found to react with BMT to form low- Q phases which prevented densification. The microwave dielectric properties of undoped BMT with a densification of 93.1% of the theoretical density were ε r = 24.8 , τ f = 8 ppm / ° C and Q u× f=80,000 GHz . The BMT doped with 1.0 wt% of B 2O 3 has Q u× f=124,700 GHz , ε r = 24.2 , and τ f = - 1.3 ppm / ° C . The unloaded Q factor of 0.2 wt% ZnO–B 2O 3-doped BMT was 136,500 GHz while that of 1.0 wt% of 5ZnO–2B 2O 3 added ceramic was Q u× f=141,800 GHz. The best microwave quality factor was observed for ZnO–B 2O 3–SiO 2 (ZBS) glass-added ceramics which can act as a perfect liquid-phase medium for the sintering of BMT. The microwave dielectric properties of 0.2 wt% ZBS-added BMT dielectric was Q u× f=152,800 GHz, ε r = 25.5 , and τ f = - 1.5 ppm / ° C .