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.