Structure and modified giant dielectric response in CaCu3(Ti1−xSnx)4O12 ceramics

The influence of Sn-substitution on structure, dielectric properties and conductivity of CaCu3Ti4O12 ceramics was investigated. Single-phase structures with space group Im3¯ were obtained up to x = 0.1 in CaCu3(Ti1−xSnx)4O12. The giant dielectric constant step became lower with Sn-substitution by depressing both the low and high temperature dielectric relaxations. The room temperature dielectric constant and dielectric loss of CaCu3(Ti1−xSnx)4O12 decreased with increasing Sn-substitution. The dielectric constant decreased from 79,846 to 31,324 when x changed from 0 to 0.1, while and the dielectric loss was suppressed from 0.083 to 0.062 (at 10 kHz). XPS analysis results confirmed the obvious decrease of Ti3+/Ti4+ and Cu+/Cu2+ ratio, and the decreased giant dielectric response was primarily attributed to the modification of the mixed-valent structure of Ti3+/Ti4+ and Cu+/Cu2+.