The structure evolution and microwave dielectric properties of MgAl2-x(Mg0·5Ti0.5)xO4 solid solutions

Abstract In the present work, MgAl2-x(Mg0·5Ti0.5)xO4 (x = 0.02, 0.04, 0.06, 0.08, 0.10) solid solutions were synthesized via the traditional solid-state reaction route. The valence state of Ti ions, crystal structural characteristics, and microwave dielectric properties were discussed. A solid solution with spinel structure was revealed by the Rietveld refinement results. The partial substitution of (Mg0·5Ti0.5)3+ for Al3+ lowered the sintering temperature and improved the Q × f value of MgAl2O4 ceramic. The MgAl2-x(Mg0·5Ti0.5)xO4 solid solutions with x = 0.06 can be well sintered at 1425 °C in an oxygen atmosphere for 8 h and exhibits excellent microwave dielectric properties with er = 9.1, Q × f = 98,000 GHz, τf = −61.36 ppm/°C. The sintering temperature of MgAl1·94(Mg0·5Ti0.5)0.06O4 microwave dielectric ceramics was approximately 200 °C lower than that of conventional MgAl2O4 ceramics.