Effect of B_2O_3 on the microstructure and microwave dielectric properties of Ba(Mg_(1/3)Nb_(2/3))O_3 ceramics

摘要

The influences of different doping contents of additive B_2O_3 on the sintering behavior, microstructure and microwave properties of Ba(Mg_(1/3)Nb_(2/3))O_3 (BMN) microwave ceramics were studied. The main phase in the sintered ceramics was crystallized as Ba(Mg_(1/3)Nb_(2/3))O_3 (BMN). Ba_2B_2O_5 as the secondary phase was observed with x ≥ 10. Scanning electron microscopy (SEM) analysis revealed that the photograph of optimally nonstoichiometric ceramics sintered at 900 °C for 5 h displayed a dense microstructure. The dielectric properties and microstructures of BMN ceramics were very sensitive to the nonstoichiometry. The addition of B_2O_3 had a positive influence on the Q×∫ value, for example the sample with x = 7 showed the highest Q×∫ value of 89,800 GHz. Finally, excellent microwave dielectric properties (ε_r = 31.6, Q×∫= 89,800 GHz and τ_∫ = 3.6 ppm/°C) were achieved for the sample with x = 7 sintered at 900 °C for 5 h.