Structure, chemical bond, and microwave dielectric properties of (Sr<subscript>1−x</subscript>Ca<subscript>x</subscript>)<subscript>2</subscript>(Ti<subscript>1−x</subscript>Sn<subscript>x</subscript>)O<subscript>4</subscript> ceramics.

Dense (Sr 1−x Ca x ) 2 (Ti 1−x Sn x )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 (ε r ) was mainly determined by the ionic polarizability per unit volume. Qf value was closely associated with the increasing amount of Sr 3 Ti 2 O 7 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. τ 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 ε r = 33.6, Qf = 73,150 GHz, and τ f = 115 ppm/°C. [ABSTRACT FROM AUTHOR]

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