Microwave Dielectric Properties of Sr-Substituted Ba(Mg0.5W0.5)O3 Ceramics

The phase evolution, microstructure, and microwave dielectric properties of Sr-substituted Ba(Mg 0.5 W 0.5 )O 3 ceramics, i.e., (Ba 1-x Sr x )(Mg 0.5 W 0.5 )O 3 (0 x 0.30), sintered at 1700C for 1 h were investigated. All compositions showed a 1 : 1 ordered perovskite structure. In all the compositions, BaWO 4 was detected as the secondary phase. With increasing x in (Ba 1-x Sr x ) (Mg 0.5 W 0.5 )O 3 , the lattice parameter increased linearly, indicating that a substitutional solid solution occurred. All compositions exhibited a dense microstructure. The value of r increased slightly with increasing x. The value of Q f 0 increased with the increase in x up to x = 0.10 and reached a saturated value of about 100,000 GHz. The composition for x = 0.20, i.e., (Ba 0.80 Sr 0.20 )(Mg 0.5 W 0.5 )O 3 , sintered at 1700C for 1 h exhibited superior microwave dielectric properties of r = 19.6, Q f 0 = 99,358 GHz, and f = 0.0 ppm/C, respectively. Key words : Ba(Mg 0.5 W 0.5 )O 3 , Ordered perovskite, Dielectric constant, Quality factor, Temperature coefficient of resonant frequency