Microwave and broadband dielectric properties of Ni substituted MgTiO₃ ceramics

The present study reports the temperature dependence of dielectric response of Ni doped MgTiO₃ ceramics over a broad frequency range. (Mg_1−x Ni _x )TiO₃ (x = 0.00–0.07) ceramics are prepared by a solid-state reaction process. The processing parameters are optimized to achieve maximum relative density. Among all the samples, (Mg_0.95Ni_0.05)TiO₃ (MNTO) ceramics is exhibited the highest density with the best microstructure at 1300 °C. The optimum microwave dielectric properties (ε _r  ~ 17.44, Q × f ₀ ~ 181 THz) are displayed by the sample doped with x = 0.05 wt%. The detailed dielectric studies are performed on (Mg_0.95Ni_0.05)TiO₃ composition in two different frequency ranges, 100 Hz–100 kHz at 298–358 K and 1–100 MHz at 133–503 K, respectively. A dielectric constant of 18.26 at 100 MHz is observed for (Mg_0.95Ni_0.05)TiO₃ specimen at temperature 503 K. The frequency dependent conductivity is explained based on the basis of Jonscher power law. Further, the DC conductivity results obey the Arrhenius law, and the obtained activation energies are found to be 0.41 and 0.06 eV for (Mg_0.95Ni_0.05)TiO₃ ceramics, measured at 100 MHz for high temperature (293–503 K) and cryogenic temperatures (133–293 K), respectively.