Microstructure and microwave dielectric properties of (1 ‒ x)Ba[(Zn0.6Mg0.4)1/3Nb2/3]O3‒xBaSnO3 ceramics

Abstract

(1 ‒ x)Ba[(Zn_0.6Mg_0.4)_1/3Nb_2/3]O₃‒xBaSnO₃ ((1 ‒ x)BZMN‒xBS, x = 0.2, 0.25, 0.3, 0.35) ceramics were prepared by a conventional solid-phase reaction method, and their crystal structures and microwave dielectric properties were investigated. Ba[(Zn_0.6Mg_0.4)_1/3Nb_2/3]O₃ and BaSnO₃ formed a perovskite solid solution with trace amounts of barium niobium oxide as a second phase. Raman spectroscopy confirms the presence of 1:1 and 1:2 short-range ordered structures in the ceramics. The doping of Sn⁴⁺ hinders the growth of grains and leads to a decrease in grain size. The dielectric constant decreases with increasing x values. The grain size, B-site Rattling effect and B-site short-range ordering together determine the Qf value of the (1 ‒ x)BZMN‒xBS ceramics, which reaches a maximum value of 62 203 GHz at x = 0.3. τ_f decreases as the value of x increases. The main mechanism regulating the (1 ‒ x)BZMN‒xBS ceramics τ_f is ion polarizability dilution. 0.75BZMN‒0.25BS ceramics have the best dielectric properties: ε_r ∼ 29.42, τ_f ∼ ‒0.74 ppm/°C, and Qf ∼ 57 256 GHz. The raw material cost of the 0.75BZMN‒0.25BS ceramics is nearly 20% lower than that of Ba[(Mg_0.4Ni_0.6)_1/3Nb_2/3]O₃ and Ba[(Co_0.8Mg_0.2)_1/3Nb_2/3]O₃ ceramics, implying that the ceramics have a good prospect for application.