The Enhanced Thermal Stability of (Mg_0.95Ni_0.05)₂TiO₄ Dielectric Ceramics Modified by a Multi-Phase Method

The thermal stability of (Mg_0.95Ni_0.05)₂TiO₄ dielectric ceramics has been improved by mixing with CaTiO₃ phases owing to higher positive temperature coefficients. The pure (Mg_0.95Ni_0.05)₂TiO₄ and the mixture phase systems of CaTiO₃-modified (Mg_0.95Ni_0.05)₂TiO₄ were verified by XRD diffraction patterns to ensure the crystallite of different phases. The microstructures of the CaTiO₃-modified (Mg_0.95Ni_0.05)₂TiO₄ were observed by SEM and EDS to investigate the relation between element ratios and grains. As a result, it can be seen that the thermal stability of the CaTiO₃-modified (Mg_0.95Ni_0.05)₂TiO₄ can be effectively enhanced, compared with the pure (Mg_0.95Ni_0.05)₂TiO₄. Moreover, the radio frequency dielectric performances of CaTiO₃-modified (Mg_0.95Ni_0.05)₂TiO₄ dielectric ceramics are strongly dependent upon the density and the morphology of the specimens. The champion sample with the ratio of (Mg_0.95Ni_0.05)₂TiO₄ and CaTiO₃ of 0.92:0.08 showed an ε_r value of 19.2, an Qf value of 108,200 GHz, and a τ_f value of -4.8 ppm/°C, which may encourage (Mg_0.95Ni_0.05)₂TiO₄ ceramics to broaden the range of novel applications and match the requirements of 5G or next-generation communication systems.