Ionic occupation, structures, and microwave dielectric properties of Y3MgAl3SiO12 garnet-type ceramics

The Y3MgAl3SiO12 ceramics with pure phase were successfully synthesized by solid-state sintering reaction method for the first time. Their microwave dielectric properties were investigated as a function of sintering temperature. Their microstructure characteristics and ionic occupation sites of tetrahedral and octahedral units were characterized and analyzed by SEM& energy dispersive spectrometer (EDS) and Rietveld refinement of X-ray powder diffraction data. Crystal structure of Y3MgAl3SiO12 is isostructural to Y3Al5O12 with a cubic garnet structure and space group of Ia-3d, which contains YO8 dodecahedra, (Mg/Aloct)O6 octahedral, and (Si/Altet)O4 tetrahedral units. The Qf and Εr values of different samples are strongly dependent on the distribution of grain sizes, grain sizes, and porosity. The samples sintered at 1550°C exhibit optimized microwave dielectric properties with relative permittivity (ɛr) of 10.1, Qf values of 57 340GHz (at 9.5 GHz), and τf values of −32 ppm/°C. Such properties indicate potential application of Y3MgAl3SiO12 as microwave substrates. © 2017 The American Ceramic Society