Improved dielectric and non-ohmic properties of (Zn + Zr) codoped CaCu3Ti4O12 thin films

The good dielectric and non-ohmic properties of CaCu₃Ti₄O₁₂ and CaCu_2.95Zn_0.05Ti_4-xZr_xO₁₂ (x?=?0, 0.05 and 0.10) thin films prepared by a sol-gel method were determined. The enhanced dielectric properties, with a dielectric constant of ${\epsilon }^{\text{'}}$ ≈ 4357 and a dielectric loss of tan δ?≈?0.019, of the CaCu_2.95Zn_0.05Ti_3.95Zr_0.05O₁₂ (ZnZr05) thin film at 1?kHz and room temperature were investigated. The XPS spectrum showed that the ZnZr05 film can produce copper vacancies V_Cu” and mixed valence structures for Cu⁺/Cu²⁺ and Ti³⁺/Ti⁴⁺ inside the crystal. The ZnZr05 film maintained a high dielectric constant due to the large grain sizes and the presence of the mixed valence structures, while its low tan δ was attributed to an increase in the V_Cu” concentration. At the same time, the enhanced nonlinear coefficient (4.2) and low leakage current (193?μA) of the ZnZr05 film were explained in detail.