Effect of AETiO3 (AE = Mg, Ca, Sr) doping on dielectric and varistor characteristics of CaCu3Ti4O12 ceramic prepared by the sol–gel process

• Alkaline-earth metal titante AETiO3 doped CCTO ceramics were prepared.
• All the samples show a strong nonlinear relationship between E and J.
• Good frequency stability can be observed in the samples.
• The best-reported dielectric loss value of CCTO ceramic of 0.0243 was obtained.

Pure and alkaline-earth metal titante AETiO3 (AE = Mg, Ca, Sr)-doped CCTO ceramics were prepared by the sol–gel process, and their crystalline structure, microstructural and electrical properties were investigated. The similar doping effects with the existence form of metal titante in CCTO, decreasing the grain size and raising the threshold voltage can be observed in CaTiO3-doped and SrTiO3-doped CCTO ceramics. For MgTiO3-doped CCTO, its grain size increases with the doping amount increasing, the reason can be attributed to the substitution of Mg2+ for Cu2+ in CCTO lattice to increase the liquid Cu-rich phase during sintering processes. In line with IBLC model, the much higher dielectric constant was observed in MgTiO3-doped CCTO ceramics due to their larger grain size. All the samples show a strong nonlinear relationship between electric filed (E) and current density (J). The best-reported dielectric loss value of CCTO ceramic of 0.0243 was obtained in the x = 0.1CaTiO3-doped sample at 104 Hz.

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