An investigation on the solid-state reactions in CaCu 3Ti 4O 12–ZnNb 2O 6 system

Abstract

We investigated the solid-state reactions between CaCu 3Ti 4O 12 and ZnNb 2O 6 oxides with a molar ratio of 1:1 in air at temperatures from 600 to 1000 °C. Solid-state reactions between CaCu 3Ti 4O 12 and ZnNb 2O 6 occurred readily around 900 °C and above. The reaction products were Cu 0.5Ti 0.5NbO 4, CaNb 2O 6, and Zn 2TiO 4 (and/or ZnCuTiO 4). A substance having a set of X-ray diffraction peaks similar to that of CaCu 3Ti 4O 12 was observed, and it is believed to be a solid solution of CaCu 3Ti 4O 12 formed by the partial substitution of Nb 5+ for Ti 4+ ions. The lattice constant of this solid solution is greater than that of CaCu 3Ti 4O 12. The reaction behaviors of CaCu 3Ti 4O 12–Nb 2O 5 system were also studied in order to better understand the reactions of the CaCu 3Ti 4O 12–ZnNb 2O 6 system. In addition to the formation of solid solution between CaCu 3Ti 4O 12 and Nb 2O 5, solid-state reactions between CaCu 3Ti 4O 12 and Nb 2O 5 also occurred simultaneously.