Internal relations between crystal structures and dielectric properties of (1-x)BaWO4-xTiO2composite ceramics

(1-x)BaWO4-xTiO(2)(x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25, BWT) ceramics were prepared by traditional solid-state method. The XRD patterns indicate that the BWT ceramics exist as composites, and the Raman spectra show that as TiO(2)increases, thev(ext)mode shifts to a low wavenumber and the Ba-O bond length decreases. The variations in FWHM values of thev(3)(E-g) modes and c/a values indicate the changes in the ordered structures that lead to the increase in dielectric loss. The infrared spectra were fitted by the FPSQ model, and the external mode (E-u) contributes most to the dielectric properties, which is related to the Ba-O bond vibration. With the increasein xvalues, the tau(f)values increase from - 101.61 to - 6.71 ppm/degrees C, the epsilon(r)values increase from 8.03 to 9.49, and the 0.75BaWO(4)-0.25TiO(2)ceramic with stable temperature coefficient was obtained:epsilon(r) = 9.49,Q x f = 20,602 GHz (f = 17.99 GHz),tau(f) = - 6.71 ppm/degrees C.