Improved dielectric properties of CaCu3-xSnxTi4O12 ceramics with high permittivity and reduced loss tangent

The structural and electrical parameters of sintered CaCu3-xSnxTi4O12 ceramics (x = 0, 0.05, and 0.10) were systematically investigated. Single-phase CaCu3Ti4O12 was detected in all-ceramic samples. The grain size in the CaCu3-xSnxTi4O12 ceramics decreased as x increased. A high dielectric permittivity of similar to 6736-19,992 and a reduced loss tangent of similar to 0.028-0.033 was obtained in the ceramics with x = 0.05 and 0.10. In addition, the temperature stability of the dielectric permittivity and loss tangent also improved by doping with Sn ions. The dielectric response of the CaCu3-xSnxTi4O12 ceramics was closely associated with an internal barrier layer capacitor model. X-ray photoelectron spectroscopy indicated the existence of mixed Cu+/Cu2+ and Ti3+/Ti4+ in all ceramic samples, which promoted the hopping of electrons between Cu+ <-> Cu2+ and Ti3+ <-> Ti4+ and was the possible origin of semiconducting grains in the samples. The presence of Sn2+ was detected by X-ray photoelectron spectroscopy indicated a reduction in the oxidation state of the Sn ions due to the charge compensation that occurred for the replacement of Cu host sites.