Structure and Dielectric Properties of Sc~(3+)- and Ru~(4+)-doped BZN Based Ceramics

The dense Bi1.4Sc0.1Zn Nb1.5-xRuxO7 ceramics were prepared by traditional solid state reaction. The effect of Sc3+ and Ru4+ co-substitution on the phase structure, crystal chemistry and dielectric properties of Bi2O3-ZnONb2O5 were investigated. The results reveal that all doped samples show a pure α-BZN phase structure. When x=0.055 mol, the intensity of X-ray diffraction becomes weak and diffraction peaks broaden. With the increase of x, the lattice constant a and the average distance R(A-O') of the ceramics decrease. The bond valance calculation show that the AV(O')[A4] and oxygen ξ parameter of 48f(O) increase, but the AV(O)[A2B2] gradually decreases with the amount of Ru4+ increasing. Meanwhile, the dielectric constant of samples decreases and the dielectric loss increases. The dielectric relaxation characteristics are weakened at room temperature while the relaxation behavior at low temperature is obvious. With increasing dopant, Tm shifts toward higher temperature. The er-T curves of samples are fitted by the modified Curie-Weiss' s(C-W) formula. The calculations show that the degree of dielectric relaxation(γ) decreases from 1.57 to 1.33 when the Ru4+ content increases from 0 to 0.04 mol.