Effect of Co-substitution on the sintering characteristics and microwave dielectric properties of Li2MgTiO4 ceramics

Abstract Rock-salt-structured Li 2 (Mg 1−x Co x )TiO 4 ( x = 0, 0.05, 0.10, 0.15 and 0.2) ceramics were successfully prepared via the conventional solid-state ceramic route in the present work. The effects of Co 2+ content on sintering characteristics, crystal structure and microwave dielectric properties of Li 2 MgTiO 4 ceramics were systematically investigated. Raman spectra and X-ray diffraction analysis revealed that the Li 2 (Mg 1−x Co x )TiO 4 ceramics could form single phase within the range of 0.00 ≤ x ≤ 0.20. As the Co 2+ content gradually increased, the dielectric constant of the solid solution gradually increased from 15.60 to 16.93, which was closely related with the variation of polarizability as well as the Raman shift in typical vibration modes. The thermal stability was also adjusted to a certain extent, and near-zero τ f values could be found at x = 0.05 and 0.10. Although the dielectric loss gradually increased with the increasing Co 2+ content, a good combination of microwave dielectric property of e r = 15.7, Q × f = 119,600 GHz and τ f = −2.67 ppm/°C could be found in the Li 2 (Mg 0.9 Co 0.1 )TiO 4 ceramics sintered at 1400 °C.