High-Q dielectrics using ZnO-modified Li2TiO3 ceramics for microwave applications

The microwave dielectric properties of the (1 − x)Li2TiO3–xZnO (x = 0.1–0.5) ceramic system prepared by mixed oxide route have been investigated. The rock-salt structured (1 − x)Li2TiO3–xZnO were characterized by using X-ray diffraction spectra, scanning electron microcopy (SEM). The dielectric properties are strongly dependent on the compositions, the densifications and the microstructures of the specimens. The decrease of Q × f value at high-level ZnO addition (x > 0.3) was owing to the intensity of the (0 0 2) superstructure reflection decreased and became disordered rock-salt structure. For practical applications, a new microwave dielectric material 0.7Li2TiO3–0.3ZnO is suggested and it possesses a good combination of dielectric properties with an ε r of ∼22.95, a Q × f of ∼99,800 GHz (measured at 8.91 GHz), and a τ f of ∼0 ppm/°C. A low-loss dielectric resonant antenna using aperture-coupled cylindrical dielectric resonant was designed and fabricated using the proposed dielectric to study its performance.