Effects of structural characteristics on microwave dielectric properties of Li2Mg(Ti1−xMnx)3O8 ceramics

Dependence of microwave dielectric properties on the structural characteristics of Li2Mg(Ti1−xMnx)3O8 ceramics were investigated as a function of Mn4+ ion contents (0 ≤ x ≤ 0.1). A single phase Li2MgTi3O8 with cubic spinel structure was obtained up to x = 0.06, with a further increase of the substitution content, the second phase of Li2MgMn3O8 and Li2MnO3 could be detected. Dielectric constant εr decreased with the increasing of the x values, which was due to the decreasing of bond ionicity. The Q × f values had a close relationship with the lattice energy. The τƒ values were dependent on the Ti-site bond energy. As the bond energy of Ti-site decreased, the τf values shift to the negative direction which was indicated the system tend to instable. An improved quality factor with Q × ƒ = 55, 300 GHz was obtained for Li2Mg(Ti1−xMnx)3O8 (x = 0.06) ceramics sintered at 1100 °C for 4 h.