Chemistry, structure and properties of bismuth copper titanate pyrochlores

Copper containing bismuth titanates with pyrochlore type structure were obtained by ceramic procedure over a wide range of compositions. The results of measurement of pycnometric density of the pyrochlores and of X-ray powder diffraction structure refinement point to the preference for copper atoms to occupy the Bi3 +-sites. TGA study of a series of synthesized compounds indicates a reversible reduction of the copper (2) to copper (1). The NEXAFS Cu2p spectra of bismuth copper titanate pyrochlores point to copper being mainly in the oxidation state + 2 in these solid solutions. Electric properties were studied for single phase pyrochlores based on bismuth titanates. The results of investigations show the presence of oxygen ionic conductivity in these samples.