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

Abstract

Rock-salt-structured Li2(Mg1−xCox)TiO4 (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 Co2+ content on sintering characteristics, crystal structure and microwave dielectric properties of Li2MgTiO4 ceramics were systematically investigated. Raman spectra and X-ray diffraction analysis revealed that the Li2(Mg1−xCox)TiO4 ceramics could form single phase within the range of 0.00 ≤ x ≤ 0.20. As the Co2+ 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 τf values could be found at x = 0.05 and 0.10. Although the dielectric loss gradually increased with the increasing Co2+ content, a good combination of microwave dielectric property of εr = 15.7, Q × f = 119,600GHz and τf = −2.67ppm/°C could be found in the Li2(Mg0.9Co0.1)TiO4 ceramics sintered at 1400°C.