Pseudo Phase Diagram and Microwave Dielectric Properties of Li₂O–MgO–TiO₂ Ternary System

Li₂O–MgO–TiO₂ ternary system is an important microwave dielectric ceramic material with excellent properties and prospect in both scientific research and application. A phase diagram of the Li₂O–MgO–TiO₂ ternary system was established in this article, based on earlier research results and our present work. Microwave dielectric properties with compositions in different regions of the phase diagram have been analyzed. We found that the 0.33 Li₂MgTi₃O₈–0.67 Li₂TiO₃ ceramics sintered at 1200°C exhibited excellent dielectric properties: Q × f value = 80 476 GHz (at 7.681 GHz), ε_r = 24.7, τ_f = +3.2 ppm/°C. We also designed two ceramic systems in the Li-rich region of the Li₂O–MgO–TiO₂ ternary system, which received little attention in the past decades, because many excellent single-phase ceramics, such as Li₂MgTiO₄, Li₂MgTi₃O₈ and MgTiO₃, have been found in the Ti-rich region. The ceramic systems have low sintering temperatures but also relatively poor dielectric properties.