Structural dependence of microwave dielectric properties of spinel structured Mg-2(Ti1-xSnx)O-4 solid solutions: Crystal structure refinement, Raman spectra study and complex chemical bond theory

摘要

Mg-2(Ti1-xSnx)O-4 (x = 0-1) ceramics were prepared through conventional solid-state method. This paper focused on the dependence of microwave dielectric properties on crystal structural characteristics via crystal structure refinement, Raman spectra study and complex chemical bond theory. XRD spectrums delineated the phase information of a spinel structure, and structural characteristic of these compositions were achieved with the help of Rietveld refinements. Raman spectrums were used to depict the correlations between vibrational phonon modes and dielectric properties. The variation of permittivity is ascribed to the Mg-2(Ti1-xSnx)O-4 average bond covalency. The relationship among the B-site octahedral bond energy, tetrahedral bond energy and temperature coefficient are discussed by defining on the change rate of bond energy and the contribution rate of octahedral bond energy. The quality factor is affected by systematic total lattice energy, and the research of XPS patterns illustrated that oxygen vacancies can be effectively restrained in rich oxygen sintering process. Obviously, the microwave dielectric properties of Mg-2(Ti1-xSnx)O-4 compounds were obtained (epsilon(r) = 12.18, Q x f = 170,130 GHz, tau(f) = -53.1 ppm/degrees C, x = 0.2).