A novel ultra-high Q microwave dielectric ceramic ZnMgTiO4 with spinel structure

Novel ultra-high Q ceramic ZnMgTiO4 was prepared using solid-state synthesis. For the first time, the crystal structure, sintering behaviour and microwave dielectric properties of ZnMgTiO4 ceramic were investigated. ZnMgTiO4 ceramics formed a cubic spinel (space group Fd 3‾ m) single-phase for sintering within 1340 °C-1400 °C, with Zn2+ occupying the tetrahedral site, Mg2+ and Ti4+ distributing randomly in the octahedral site, whereas a trace of MgTiO3 appeared at 1420 °C. At 1400 °C: ϵr = 16.8, Q × f = 202,021 GHz, and τf = −38 ppm/°C, excellent microwave dielectric properties were obtained, and CaTiO3 compensated the negative τf to near-zero. A substantial 29% deviation between the measured ϵr and the theoretical ϵth could be attributed to the potential underestimation of ionic polarizability of Ti4+. Phillips–Van Vechten–Levine theory suggested that dielectric polarization and intrinsic loss were primarily influenced by the Ti–O bonds. As a conclusion, ZnMgTiO4 ceramic emerges as a promising candidate for 5G/6G wireless communication devices.