Crystal structure and microwave dielectric properties of Ba[(Zn1-xMgx)1/3Nb2/3]O3 ceramics

Ba[(Zn1-xMgx)1/3Nb2/3]O3(x = 0 ~ 0.9) ceramics were prepared by the traditional solid-phase reaction sintering method. In this paper, the effects of MgO doping on the shrinkage, density, phase composition, crystal structure, microstructure, and microwave dielectric properties of Ba(Zn1/3Nb2/3)O3 (BZN) ceramics were investigated. The phase constituents, crystal structure, and microstructure of the ceramics were studied by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The results showed that Ba(Zn1/3Nb2/3)O3 as the main phase, and the secondary phase Ba5Nb4O15 was detected with high MgO content (x > 0.3). However, the appearance of secondary Ba5Nb4O15 directly led to the deterioration of the microwave dielectric properties of the samples. Ba[(Zn1–xMgx)1/3Nb2/3]O3 (x = 0.3) ceramics sintered at 1500 °C for 4 h possessed superior dielectric properties: εr = 36.31, Q × f = 111,326 GHz, τf = + 12.1 ppm/°C. Such the ceramics could be used to make dielectric resonators and stable oscillators.