Effects of MgO doping on microwave dielectric properties of yttrium aluminum garnet ceramics

In this study, the crystal structures and microwave dielectric properties of the Y 3 Al 5 O 12 garnet (YAG) doped with Magnesium (Mg) were investigated. The samples were prepared by a method that the isostatic pressing technique was introduced into the conventional preparation of microwave dielectric ceramics . From XRD patterns of resulted compound, we see Y 3 Al 5−x Mg x O 12–1/2x ( x  = 0–0.045) samples form a solid solution with MgO. The lattice parameters of the Y 3 Al 5−x Mg x O 12–1/2x samples have been refined by the Rietveld method, and the unit cell volume of samples swell up slightly as the x value increases. The SEM images demonstrate that the porosity in the system has been effectively eliminated and the values of the relative density significantly increase due to the addition of Mg 2+ , which is conducive to the improvement of Q × f value. The TEM results present the high crystallinity of Y 3 Al 5−x Mg x O 12–1/2x samples. The Raman spectra study illustrates the relationship between the vibrational FWMH values corresponding to the internal loss and the Q × f value. Finally, the Q × f value has been dramatically promoted from 133,209 GHz at x  = 0–218,168 GHz at x  = 0.035.