Microwave dielectric properties of Li₃Mg₂SbO₅F₂ oxyfluorides ceramics produced by reaction-sintering method

By a reaction-sintering approach Li3Mg2SbO5F2 oxyfluorides ceramics were prepared. The sinterability, microstructure, phase transition along with microwave dielectric performances of present ceramics were researched. A gradual phase transition from cubic to orthorhombic in Li3Mg2SbO5F2 ceramics sintered above 825 degrees C was identified by XRD refinement analysis. The microwave dielectric performances of present ceramics were closely correlated with its phase transition process and microstructure. Typically, optimal microwave dielectric performances (epsilon(r) similar to 8.1, tau(f) similar to -54.0 ppm/degrees C, Q x f similar to 68,500 GHz (under 9.2 GHz)) were achieved for 825 degrees C-sintered Li3Mg2SbO5F2 ceramics. Moreover, a cylindrical dielectric resonator antenna fabricated from Li3Mg2SbO5F2 ceramics exhibited a maximum return loss (S-11) of -30.3 dB, a maximum gain of 5.3 dB and VSWR of 1.1 at the center frequency of 11.6 GHz, and impedance bandwidth of 300 MHz (at -10 dB), respectively.