Structural characterization of Bi–Zn–Nb–O cubic pyrochlores

Structure and dielectric properties of oxide dielectrics with the composition of Bi1.5ZnNNb2.5−NO8.5−1.5N (with N=0.73 to 1.20) have been studied. These samples were treated at 1050 °C for 4 h. The cubic pyrochlore phase was found to be predominant as from X-ray diffraction and Raman spectra analysis. Lattice constant of the cubic pyrochlore and dielectric constant of the sample have been found to increase with the increase of Zn content. A model of the structural defects has been proposed to explain the stabilization of the pyrochlore structure. The limitation of composition for the formation of single cubic pyrochlore phase has been attributed to the distribution of oxygen defects.