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

Four control experiments (S1: Y 3 Al 5 O 12 , S2: Y 3 Al 5 O 12 +1 wt%Nb 2 O 5 , S3: Y 3 Al 4.955 Nb 0.045 O 12 , S4: Y 2.955 Al 5 Nb 0.045 O 12 ) were designed to investigate the co-effects of Nb 2 O 5 and non-stoichiometry on the microwave dielectric properties of Y 3 Al 5 O 12 . The beneficial results of Nb 2 O 5 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 ( ε r  ∼ 10.37, Q  ×  f  ∼ 161,724 GHz and τ f  ∼ -33.8 ppm/°C).