Co-effects of Nb2O5 and stoichiometric deviations on the microwave dielectric properties of Y3Al5O12

Four control experiments (S1: Y3Al5O12, S2: Y3Al5O12+1 wt%Nb2O5, S3: Y3Al4.955Nb0.045O12, S4: Y2.955Al5Nb0.045O12) were designed to investigate the co-effects of Nb2O5 and non-stoichiometry on the microwave dielectric properties of Y3Al5O12. The beneficial results of Nb2O5 doping are demonstrated based on X-ray patterns, electron diffraction information, Rietveld refinement, and micromorphological characterization. Differences in dielectric properties were explored using lattice defects, ion polarizability, bond valence, and Raman spectroscopy. In contrast, the Y-deficient sample (S4) possesses the best dielectric properties (εr ∼ 10.37, Q × f ∼ 161,724 GHz and τf ∼ -33.8 ppm/°C).