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 Y3Al5O12 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 Y3Al5−xMgxO12–1/2x (x = 0–0.045) samples form a solid solution with MgO. The lattice parameters of the Y3Al5−xMgxO12–1/2x samples have been refined by the Rietveld method, and the unit cell volume of samples swell up slightly as thexvalue 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 Mg2+, which is conducive to the improvement of Q×f value. The TEM results present the high crystallinity of Y3Al5−xMgxO12–1/2x 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.