Structure Stability and Microwave Dielectric Properties of (1 −  x ) Ba ( Mg _1/2 W _1/2 ) O ₃  +  x Ba ( Y _2/3 W _1/3 ) O ₃ Ceramics

Abstract

The structure stabilities of double perovskite ceramics‐ (1 − x ) Ba ( Mg 1/2 W 1/2 ) O 3 + x Ba ( Y 2/3 W 1/3 ) O 3 (0.01 ≤ x ≤ 0.4) have been studied by X‐ray powder diffraction ( XRD ), scanning electron microscopy ( SEM ), and Raman spectrometry in this study. The microwave dielectric properties of the ceramics were studied with a network analyzer at the frequency of about 8–11 GHz. The results showed that all the compounds exhibited face‐centered cubic perovskite structure. Part of Y 3+ and W 6+ cations occupied 4 a ‐site and the remaining Y 3+ and Mg 2+ distributed over 4 b ‐site, respectively, and kept the B‐site ratio 1:1 ordered. Local ordering of Y 3+ /Mg 2+ on 4 b ‐site and Y 3+ /W 6+ cations on 4 a ‐site within the short‐range scale could be observed with increasing Y‐doping content. The decomposition of the double perovskite compound at high temperature was successfully suppressed by doping with Y on B‐site. However, Ba 2 Y 0.667 WO 6 impurity phase appeared when x > 0.1. The optimized dielectric permittivity increased with the increase in Y doping. The optimized Q × f value was remarkably improved with small amount of Y doping ( x ≤ 0.02) and reached a maximum value of about 160 000 GHz at x = 0.02 composition. Further increasing in Y doping led to the decrease in Q × f value. All compositions exhibited negative τ f values. The absolute value of τ f decreased with increasing Y‐doping content. Excellent combined microwave dielectric properties with ε r = 20, Q × f = 160 000 GHz, and τ f = −21 ppm/°C could be obtained for x = 0.02 composition.