The Structure and Microwave Dielectric Properties of MgTi_1−<i>x</i>(Mn_1/3Nb_2/3)<i>_x</i>O₃ Ceramics

Abstract

MgTi1−x(Mn1/3Nb2/3)xO3 (x = 0–0.30) ceramics were prepared via the solid-state reaction method. The phase composition, microstructure, bond characteristics, and microwave dielectric properties of MgTi1−x(Mn1/3Nb2/3)xO3 (x = 0–0.30) were systematically investigated. The MgTi1−x(Mn1/3Nb2/3)xO3 ceramics presented an ilmenite type with an R-3 space group, and the secondary-phase MgTi2O5 only existed at x = 0 and 0.30. The introduction of (Mn1/3Nb2/3)4+ effectively suppressed the formation of the MgTi2O5 phase. The variation trend of the dielectric constant (εr) was the same as relative density. The quality factor (Qf) value was enhanced by the stable microstructure, which was caused via the lattice energy of Ti/(Mn1/3Nb2/3)-O bonds. And a high Qf value (353,000 GHz) was obtained for MgTi1−x(Mn1/3Nb2/3)xO3 (x = 0.04) ceramics sintered at 1250 °C. In addition, the introduction of Mn2+ ions with a larger ionic radius exacerbates the distortion of TiO6 octahedra, leading to significant fluctuations in the temperature coefficient of the resonance frequency (τf) value.

Keywords

• MgTiO₃ ceramic co-substitution
• microwave dielectric properties
• lattice energy
• octahedral distortion