Crystal structures and microwave dielectric properties of (1-x)Ba(Zn1/3Nb2/3)O3 - xBaWO4 (0 ≤ x ≤ 0.25) ceramics

The (1-x)Ba(Zn1/3Nb2/3)O-3 - xBaWO(4) (0 <= x <= 0.25) ceramics were manufactured by the conventional solid-phase reaction process, and the effects of BaWO4 addition on the phase composition, crystal structures, microstructure, and microwave dielectric properties were investigated. X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy were implemented to explore the phase composition, crystal structure and chemical states of the samples, respectively. According to XRD analysis, the main phase of the samples was assigned as Ba(Zn1/3Nb2/3)O-3 (BZN), while the secondary phases contained Ba5Nb4O15 and BaWO4. Scanning electron microscopy photographs suggested the average grain size firstly increased and then decreased with the replacement of W6+ ions to Nb5+ ions in BZN. Due to the proper substitution amount of W6+, the apparent density increased accordingly. The microwave dielectric properties were closely associated with the secondary phases and apparent density. Finally, (1-x)Ba(Zn1/3Nb2/3)O-3 - xBaWO(4) (x = 0.15) ceramics sintered at 1325 degrees C for 4 h had excellent microwave dielectric properties with epsilon(r) = 33.11, Q x f = 90,479 GHz, and tau(f) = +0.86 ppm degrees C-1.