期刊
CERAMICS INTERNATIONAL
卷 47, 期 16, 页码 22390-22396出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2021.04.248
关键词
Zn-doped CaCu3Ti4O12; Dielectric properties; Density functional theory; Nonlinear electrical properties
资金
- Basic Research Fund of Khon Kaen University
- Research and Graduate Studies Office, Khon Kaen University
- Research Network NANOTEC (RNN) program of the National Nanotechnology Center (NANOTEC), NSTDA
- Ministry of Higher Education, Science, Research and Innovation (MHESI)
- Khon Kaen University, Thailand [P1851882]
CaCu3-xZnxTi4O12 ceramics were successfully prepared by a conventional solid-state reaction method. The addition of Zn2+ significantly improved the dielectric properties of the ceramics, particularly reducing the dielectric loss tangent.
CaCu3-xZnxTi4O12 ceramics (x = 0, 0.05, 0.10) were successfully prepared by a conventional solid-state reaction method. Their structural and dielectric properties, and nonlinear electrical response were systematically inspected. The X-ray diffraction results indicated that single-phase CaCu3Ti4O12 (JCPDS no. 75-2188) was obtained in all sintered ceramics. Changes in the lattice parameter are well-matched with the computational result, indicating an occupation of Zn2+ doping ions at Cu2+ sites. The overall tendency shows that the average grain size decreases when x increases. Due to a decrease in overall grain size, the dielectric permittivity of CaCu3-xZnxTi4O12 decreases expressively. Despite a decrease in the dielectric permittivity, it remains at a high level in the doped ceramics (similar to 3,406-11,441). Besides retention in high dielectric permittivity, the dielectric loss tangent of x = 0.05 and 0.10 (similar to 0.074-0.076) is lower than that of x = 0 (similar to 0.227). A reduction in the dielectric loss tangent in the CaCu3-xZnxTi4O12 ceramics is closely associated with the enhanced grain boundary response. Increases in grain boundary resistance, breakdown electric field, and conduction activation energy of grain boundary as a result of Zn2+ substitution are shown to play a crucial role in improved grain boundary response. Furthermore, the XPS analysis shows the existence of Cu+/Cu2+ and Ti3+/Ti4+, indicating charge compensation due to the loss of oxygen lattice. Based on all results of this work, enhanced dielectric properties of the Zn-doped CCTO can be explained using the internal barrier layer capacitor model.
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