Improved dielectric properties of CaCu_(3-x)Sn_xTi_4O_(12) ceramics with high permittivity and reduced loss tangent

摘要

The structural and electrical parameters of sintered CaCu_(3-x)Sn_xTi_4O_(12) ceramics (x = 0, 0.05, and 0.10) were systematically investigated. Single-phase CaCu_3Ti_4O_(12) was detected in all-ceramic samples. The grain size in the CaCu_(3-x)Sn_xTi_4O_(12) ceramics decreased as x increased. A high dielectric permittivity of ～6736-19,992 and a reduced loss tangent of ～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 CaCu_(3-x)Sn_xTi_4O_(12) ceramics was closely associated with an internal barrier layer capacitor model. X-ray photoelectron spectroscopy indicated the existence of mixed Cu~+/Cu~(2+) and Ti~(3+)/Ti~(4+) in all ceramic samples, which promoted the hopping of electrons between Cu~+ ↔ Cu~(2+) and Ti~(3+) ↔ Ti~(4+) and was the possible origin of semiconducting grains in the samples. The presence of Sn~(2+) 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.