Microwave dielectric properties of high-Q Mg(SnxTi1−x)O3 ceramics

A series of Sn-doped Mg(SnxTi1−x)O3 ceramics were prepared using the conventional solid-state route. The influence of Sn4+ substitution for Ti4+ on the microstructure and microwave dielectric properties of Mg(SnxTi1−x)O3 ceramics was systematically investigated. Substitution with a suitable amount of Sn can eliminate the MgTi2O5 phase. The dielectric constants and temperature coefficients of resonant frequency changed slightly with the variation in Sn content in the specimens. However, the quality factors (Q) dramatically improved and were sensitive to the concentration of Sn4+. The high Q value was attributed to the uniform grain, clean and narrow grain boundary, and elimination of the MgTi2O5 phase. Moreover, the composition-optimized Mg(Sn0.05Ti0.95)O3 ceramics sintered at 1390°C exhibited excellent microwave dielectric properties of ɛr = 17.61, Q×f = 328,543 GHz, and τf = −42 ppm/°C.