Microstructure and microwave dielectric properties of MgNb2O6-ZnTa2O6 composite ceramics prepared by layered stacking method

ZnTa2O6/MgNb2O6/ZnTa2O6 layered ceramics with different volume fractions were designed and prepared to tailor the microwave dielectric properties of ZnTa2O6-MgNb2O6 composite ceramics. The crystal structure, microstructure and microwave dielectric properties of the composite ceramics were systematically investigated in this work. The formation of solid solutions at interface was confirmed by X-ray diffractometer. Scanning electron microscopy and energy dispersive spectroscopy were used to analysis the ionic diffusion behavior across the interface. The typical core-shell structure based on MgNb2O6 solid solution was clearly discerned in the composite ceramics. The ionic diffusion coefficients simulated by semi-infinite diffusion couple could give a reasonable explanation for the formation of the special structure. The tri-layered ZnTa2O6/MgNb2O6/ZnTa2O6 ceramic with the volume fraction of 6:1:6 had the optimum microwave dielectric properties of epsilon (r) = 31.98, Q x f = 82,778 GHz, and tau (f) = 0 ppm/A degrees C, demonstrating a unique potential for low-loss microwave applications in resonators, filters and antenna substrates.