In this work, microstructure, composition, and microwave dielectric properties of nominal compositions (1‐x)Li2TiO3‐xZn2SiO4 (x=0.1, 0.2, 0.3, 0.4), which were prepared by conventional solid‐state ceramic route, have been investigated. Li2TiO3 and Zn2SiO4 reacted to form Li2ZnSiO4 and Zn2Ti3O8, where Zn2Ti3O8 is formed during Zn2TiO4 cooling. The microwave dielectric properties of samples are mainly affected by the characteristics and relative content of crystal phase and densification. With the increase of x, the relative dielectric constant (ϵr) decreases gradually. The quality factor (Qf) value increases at first, reaches the maximum value at x=0.2, and then decreases. The temperature coefficient of resonance frequency (τf) value has a sharp decrease due to the increase of Li2ZnSiO4. A near zero τf of about −2.0 ppm/°C was obtained in 0.8Li2TiO3–0.2Zn2SiO4 ceramic sintered at 1150 °C for 4 h with ϵr value of 17.67, Qf value of 19,600 GHz. Thus, it could be a candidate for microwave devices.

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In this work, a series of nominal compositions MgAl2-x (Li1/3Ti2/3) x O4 (x = 0, 0.04, 0.08, 0.12, 0.16 and 0.20) ceramics were successfully prepared via the conventional solid-state reaction route. The phase compositions, microstructures, and microwave dielectric properties were investigated. The results of X-ray diffraction (XRD) and Scanning electron microscopy (SEM) showed that a single phase ceramics of MgAl2-x (Li1/3Ti2/3) x O4 with spinel structure were obtained at x ≤ 0.12, whereas the second phase MgTi2O5 appeared when x > 0.12. The cell parameters were obtained by XRD refinement. As the x values increased, the unit cell volume kept expanding. This phenomenon could be attributed to the partial substitution of (Li1/3Ti2/3)3+ for Al3+. Results showed that (Li1/3Ti2/3)3+ doping into MgAl2O4 spinel ceramics effectively reduced the sintering temperature and improved the quality factor (Qf) values. Optimum microwave dielectric properties were achieved for sample at x = 0.20 sintering at 1500℃ in oxygen atmosphere for 4 h: dielectric constant (εr) = 8.78, temperature coefficient of resonant frequency (τf) = -85 ppm/ ℃, and Qf = 62,300 GHz. The Qf value of x = 0.20 sample was about two times higher than that of pure MgAl2O4 ceramics (31600 GHz). Thus, MgAl2-x (Li1/3Ti2/3) x O4 ceramics with excellent microwave dielectric properties can be applied to 5G communications.