Novel dielectric response in B-site zirconium-doped CaCu3Ti4O12 ceramics: A structural, optical and electrical study

Abstract

In this study, the CaCu3Ti4-xZrxO12 (with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8) compounds were effectively synthesized through SSR method, and their crystalline structures, microstructures, optical, dielectric and electrical properties were analyzed and discussed in detail. A significant reduction in grain size is observed by Zr4+ doping for CCTZO ceramics. All CCTZO samples have an energy gap of ∼2.08 eV. A relatively high dielectric permittivity (ε'>103) is exhibited by all studied ceramics and impedance spectroscopy shows that they are heterogeneous electrically. The presence of Ti3+ and Cu+ ions as well as the oxygen vacancy in all samples was confirmed by XPS, resulting in structural changes that greatly affect the materials dielectric behaviour. Interestingly, CCTZO with x > 0.5 ceramics showed a dielectric resonance behaviour and were more frequency-stable than pure CCTO. More importantly, the sample x = 0.7 exhibited a higher ε′ at high frequencies which may be due to the enhancement of grains conductivity. The lowest value of dielectric loss while maintaining a relatively high ε′ was possible with the Zr doping content x = 0.1, the reason was discussed. Furthermore, the Zr doping not only enhanced the frequency-stability but also the temperature-stability of pure CCTO ceramic.