Structural Evolution and Microwave Dielectric Properties ofxZn0.5Ti0.5NbO₄-(1–x)Zn0.15Nb0.3Ti0.55O₂Ceramics

Structure and microwave properties of x Zn 0.5 Ti 0.5 NbO 4 -(1 – x )Zn 0.15 Nb 0.3 Ti 0.55 O 2 ceramics in the range of x = 0.0–1.0 were investigated. Rietveld refinement analysis and Raman spectra show that rutile- and orthorhombic-type solid solutions formed at 0–0.2 and 0.65–1, a composite at 0.2–0.64. In the solid solution regions, chemical bonds are enlarged. In this case, the Zn/Ti/Nb–O1 bond covalency and bond susceptibility are reduced, and lattice energy and thermal expansion coefficient increase along with x increases, which is mainly responsible for the development of microwave dielectric properties. Furthermore, far-infrared spectra and a classical oscillator model were used to discuss the intrinsic dielectric properties in detail. Temperature stable ceramic was obtained for x = 0.516: ε r ∼ 46.11, Q × f ∼ 27 031 GHz, and τ f ∼ −1.51 ppm/°C, which is promising for microwave applications.