New remarks on the high-polarizability perovskite-related material CaCu3Ti4O12

The article presents results from Raman scattering, EPR and static magnetization measurements in CaCu3Ti4O12, a perovskite-related material characterized by a colossal dielectric permittivity epsilon(0) . The investigated samples were pure and partially substituted in the octahedral Ti sites by other transition metals. The results from the pure material are interpreted in terms of the presence of delocalized Copper-holes. Substitutions in the Ti sites drastically change the magnetic properties and, most evidently in the case of Cr, also affect the Raman spectra. These effects correlate with the known suppression of the colossal epsilon(0) after the same kind of substitutions.