Structure, IR spectra and dielectric properties of Bi2O3-ZnO-SnO2-Nb2O5 quarternary pyrochlore

Anew series of pyrochlore compounds (Bi1.5Zn0.5)(Zn0.5-x/3SnxNb1.5-2x/3)O-7 (0 less than or equal to x less than or equal to1.5) have been prepared by the solid reaction technique. X-ray diffraction (XRD) and IR absorption spectra were used for analyzing the compositions. Single-phase specimens having cubic pyrochlore structure were obtained for various Sn content. Only one broad band ascribable to B-O stretching vibration was observed for each sample. The dielectric properties were systematically studied and the temperature dependence of the dielectric constant and dielectric loss was measured in the temperature range 150-200 degreesC. At room temperature (RT), the dielectric constant for Sn-doping Bi-based ceramics decreased and the temperature coefficient increased with increasing Sn4+ content. Rather low dielectric loss was obtained for series compositions. (C) 2002 Published by Elsevier Science Ltd and Techna S.r.l.