An investigation on the solid-state reactions in CaCu3Ti4O12–ZnNb2O6 system

We investigated the solid-state reactions between CaCu3Ti4O12 and ZnNb2O6 oxides with a molar ratio of 1:1 in air at temperatures from 600 to 1000 °C. Solid-state reactions between CaCu3Ti4O12 and ZnNb2O6 occurred readily around 900 °C and above. The reaction products were Cu0.5Ti0.5NbO4, CaNb2O6, and Zn2TiO4 (and/or ZnCuTiO4). A substance having a set of X-ray diffraction peaks similar to that of CaCu3Ti4O12 was observed, and it is believed to be a solid solution of CaCu3Ti4O12 formed by the partial substitution of Nb5+ for Ti4+ ions. The lattice constant of this solid solution is greater than that of CaCu3Ti4O12. The reaction behaviors of CaCu3Ti4O12–Nb2O5 system were also studied in order to better understand the reactions of the CaCu3Ti4O12–ZnNb2O6 system. In addition to the formation of solid solution between CaCu3Ti4O12 and Nb2O5, solid-state reactions between CaCu3Ti4O12 and Nb2O5 also occurred simultaneously.