Crystal structure, Raman spectra, and microwave dielectric performances of TiW-substituted magnesium niobite ceramics

The effect of TiW substitution on the microwave dielectric performances of MgNb2O6 ceramics prepared via solid-state reaction has been investigated using Raman scattering spectroscopy, microscopic morphology analysis, and complex chemical bond theory. The dielectric permittivity is mainly affected by porosity, molecular polarizability and crystal vibrations. The Q x f value is mainly determined by the bond covalency of the Nb-O bond and the FWHM value of the Raman spectrum. In addition, tau(f) value is mainly affected by the bond valence of the Nb-O bond. This research demonstrates that a moderate amount of (TiW)(5+) not only reduces the sintering temperature (from 1460 degrees C to 1340 degrees C) and lowers the dielectric loss, but also improves the temperature stability. The composition (x = 0.01) exhibits excellent properties: epsilon(r) = 20.67, Q x f = 117,660 GHz, and tau(f) = -45.73 ppm/degrees C, providing a promising candidate for 5 G electronic devices.