A comprehensive study on structure, microstructure and microwave-dielectric properties of (Mg1−xNix)2TiO4 ceramics (x = 0.00–0.08) for 5G wireless communications

In this communication, structural, microstructural, and microwave dielectric properties of the (Mg_1−xNi_x)₂TiO₄ (x = 0.00–0.08) ceramics prepared by a high-energy planetary ball milling (HEBM) technique are reported. All the as-prepared samples exhibit a cubic-structured which was confirmed by the X-ray diffraction patterns analysis through Rietveld refinement and the measured lattice parameters. A well-defined microstructure with maximum relative density about 98% is achieved for (Mg_0.95Ni_0.05)₂TiO₄ ceramic along with an incredible reduction in sintering temperature from 1420 to 1300 °C. It was observed that the relative density, dielectric constant, and Q × f_o values increase with increasing Ni-content up to 0.05 and decreases afterward. When concentration of x increases from 0.00 to 0.05, the Q × f_o value has tremendously boosted from 94,000 to 192,000 GHz. A fine combination of microwave dielectric properties, (ε_r ≈ 15.8, Q × f_o = 192,000 GHz at 10.24 GHz) was achieved for (Mg_0.95Ni_0.05)₂TiO₄ sample sintered at 1300 °C for 3 h. This is attributed to local distortion, highest relative density, and uniform grain growth of the specimen. In this study, ilmenite-structured (Mg_0.95Ni_0.05)TiO₃ was detected as a secondary phase. However, the existence of this secondary phase would cause no significant variation in the dielectric properties of the sample, because it possesses compatible properties as compared with the primary phase. The observed results reveal (Mg_0.95Ni_0.05)₂TiO₄ ceramic can be proposed as one of the most promising dielectric materials for 5G wireless communications.