Reaction-sintering method for ultra-low loss (Mg0.95Co0.05)TiO3 ceramics

Microwave dielectric properties and microstructures of (Mg0.95Co0.05)TiO3 ceramics prepared by a new sintering method (reaction-sintering method) were investigated. A pure phase of (Mg0.95Co0.05)TiO3 was obtained by the new method and excellent dielectric properties were observed due to uniformities of the microstructure and the phase. In contrast, the secondary phase (Mg0.95Co0.05)Ti2O5 was observed in samples prepared by conventional sintering method. In order to study the influence of secondary phase on the microwave dielectric properties quantitatively, the weight fraction of (Mg0.95Co0.05)Ti2O5 was calculated on the basis of Rietveld refinement. The pore-freeɛr values of specimens prepared by two different methods indicated that porosity plays an important role in the ɛr values of (Mg0.95Co0.05)TiO3 ceramics. Specimens sintered by reaction-sintering method at 1350 °C for 4 h possess excellent dielectric properties with an ɛr of 16.3, a Q × f value of 244,500 GHz, and a τf value of −53.5 ppm/°C.

► (Mg0.95Co0.05)TiO3 (95MCT) ceramics were obtained by reaction-sintering process.
► 95MCT ceramics sintered at 1350̊C show a pure phase composition.
► Effects of porosity and phase on microwave properties were studied quantitatively.
► Microwave properties of 95MCT were ɛr = 16.3, Q·ƒ = 244,500 GHz and tƒ = -53.5 ppm/̊C.