Structure, chemical bond, and microwave dielectric properties of (Sr1-xCax)2(Ti1-xSnx)O4 ceramics

Dense (Sr1-xCax)(2)(Ti1-xSnx)O-4 (x = 0.0, 0.05, 0.10, 0.15) ceramics were synthesized by a standard solid-state reaction method. The formation of solid-solution with an I4/mmm space group was revealed from the X-ray diffraction patterns and Rietveld refinement results. The variation of the microwave dielectric properties was systematically analyzed using the dielectric polarizability and complex chemical bond theory. The dielectric constant (epsilon(r)) was mainly determined by the ionic polarizability per unit volume. Qf value was closely associated with the increasing amount of Sr3Ti2O7 secondary phase and the declined lattice energy. Meanwhile, the variation of Qf value was further analyzed by extrapolating the intrinsic dielectric loss from the infrared reflectivity spectra. tau(f) value was successfully adjusted toward zero, which could be explained by the enhanced bond energy. The optimal microwave dielectric properties were achieved at x = 0.10, with epsilon(r) = 33.6, Qf = 73,150 GHz, and tau(f) = 115 ppm/degrees C.

Automated summary

Dense (Sr1-xCax)(2)(Ti1-xSnx)O-4 ceramics were synthesized and their microwave dielectric properties were studied. The dielectric constant was mainly influenced by the ionic polarizability, while the Qf value was associated with the amount of Sr3Ti2O7 secondary phase and lattice energy. The tau(f) value could be adjusted towards zero by enhancing the bond energy. The optimal microwave dielectric properties were achieved at x = 0.10.