Ge-doped Li3+xMg2Nb1-xGexO6 ceramics with enhanced low loss and high temperature stability properties

New high-performance materials have attracted much attention due to ever-increasing demands for advanced communication technologies. In present work, Ge-doped Li_3+xMg₂Nb_1-xGe_xO₆ (0 ≤ x ≤ 0.08) ceramics are prepared via solid-state reaction route. Microstructural analysis and crystal structure refinement reveal that moderate substitution can promote grain growth and modify crystal structure, thus enhancing microwave dielectric properties of composites. In that sense, special attention is paid to the behavior of dielectric constant ε_r, quality factor Q×f, and frequency temperature coefficient τ_f of final products. In these systems, ε_r parameter depends on the density, miscellaneous phases, and polarizability; Q×f value is shown to be influenced by Nb-O bond energy, grain size, and bulk density; finally, τ_f characteristic refers to Nb-O bond valence and NbO₆ octahedral distortion. Among above ceramics, Li_3.02Mg₂Nb_0.98Ge_0.02O₆ composite sintered at 1250 °C exhibits outstanding microwave absorption performance with ε_r = 15.32, Q×f = 969 88 GHz, and τ_f = ?8.25 ppm/°C.