Microstructure and microwave dielectric properties of MgNb 2 O 6 –ZnTa 2 O 6 composite ceramics prepared by layered stacking method

ZnTa 2 O 6 /MgNb 2 O 6 /ZnTa 2 O 6 layered ceramics with different volume fractions were designed and prepared to tailor the microwave dielectric properties of ZnTa 2 O 6 –MgNb 2 O 6 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 MgNb 2 O 6 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 ZnTa 2 O 6 /MgNb 2 O 6 /ZnTa 2 O 6 ceramic with the volume fraction of 6:1:6 had the optimum microwave dielectric properties of ε r = 31.98, Q × f = 82,778 GHz, and τ f = 0 ppm/°C, demonstrating a unique potential for low-loss microwave applications in resonators, filters and antenna substrates.