Crystal structure, infrared spectra and microwave dielectric properties of ultra low-loss Li2Mg4TiO7 ceramics

- Rock-salt structured Li2Mg4TiO7 was firstly prepared with excellent microwave properties.
- Excellent property of εr = 13.43, Q·f = 233,600 GHz and τf = −7.24 ppm/°C was obtained at 1600 °C.
- IR reflectivity spectrum was firstly used to analyze resonant modes in Li2Mg4TiO7.

The low-loss Li2Mg4TiO7 dielectric ceramics were prepared by the conventional solid-state method. The relationship among sintering behavior, phase composition, microstructure and dielectric properties of Li2Mg4TiO7 ceramics was investigated. All the sintered samples exhibited the single phase with rock-salt structure belonging to Fm-3m space group. The higher Q·f values of samples above 1500 °C were depending on crystal structure and phase composition. IR reflectivity spectrum indicated that the dielectric constant of Li2Mg4TiO7 was mainly affected by the polar optical phonons. Typically, the ceramics sintered at 1600 °C exhibited excellent microwave dielectric properties with εr = 13.43, Q·f = 233,600 GHz and τf = −7.24 ppm/°C.