Effect of Ti-site Non-Stoichiometry on the Microwave Dielectric Properties of Li2Mg9Ti7-xO24 Ceramics

A series of Li 2 Mg 9 Ti 7- x O 24 (0.1 ≤ x ≤ 0.3) ceramic materials were synthesized via a conventional solid-state reaction. The influence of non-stoichiometric Ti-site content on sintering behavior, phase composition and dielectric properties was systematically studied. Rietveld-refined XRD patterns confirmed that the ceramics exhibited inverse spinel structures. The vibrational properties of the ceramic samples were analyzed using Raman spectroscopy. The results showed that an appropriate Ti-site deficiency (0.1 ≤ x ≤ 0.3) not only reduced the optimal sintering temperature by 40°C but also suppressed impurity formation, as evidenced by reduced minor XRD peaks. Notably, the Li 2 Mg 9 Ti 6.9 O 23.8 ceramic sintered at 1260°C for 4h achieved optimal microwave dielectric properties (MDPs): ε r = 16.25, Q×f = 71,104 GHz and τ f = –48.8 ppm/°C. Furthermore, a novel dielectric resonator antenna (DRA) was designed and simulated based on Li 2 Mg 9 Ti 6.9 O 23.8 ceramics. The DRA exhibited a gain of 6.42 dB and a bandwidth of 280 MHz, highlighting its potential for applications in microwave communication systems.