Crystal Structural and Microwave Dielectric Properties of Y 2.97 Re 0.03 Al 5 O 12 (Re = La, Sm, Gd, Er, Yb) Ceramics

The Y 2.97 Re 0.03 Al 5 O 12 ceramics have been prepared with Y 3+ ions substituted by rare-earth ions (Re = La, Sm, Gd, Er, Yb). We have analyzed the phase composition, crystal structure, surface micromorphology, and microwave dielectric properties of the Y 2.97 Re 0.03 Al 5 O 12 ceramics. The results of x-ray diffraction and Rietveld refinement show that with a doping amount of x = 0.03, a stable Y 3 Al 5 O 12 phase can be formed, while the crystal structure is slightly changed. Samples of each component illustrate different characteristics of grain boundaries that influence the microwave dielectric properties. Based on the Phillips–Van Vechten–Levine (P-V-L) theory, the ionicity, lattice energy, and bond energy of Y 2.97 Re 0.03 Al 5 O 12 ceramics have been calculated to characterize the relative dielectric constant, quality factor, and temperature coefficient, respectively. Among all the samples, La 3+ ions substitution significantly improves the quality factor of the YAG ceramics . Optimal microwave dielectric properties ( ε r = 10.73, Q × f = 178102 GHz, τ f = − 35.18 ppm/°C) of Y 2.97 La 0.03 Al 5 O 12 ceramics were prepared at 1700 °C for 9 h.