CaCu3Ti4O12 （CCTO） ceramics doped with Zr^4＋ were prepared. Effects of Zr^4＋ on microstructure, dielectric properties and conduction behavior of CaCaCu3Ti4O12 （x=0, 0.05, 0.10, 0.20） ceramics were studied in the...CaCu3Ti4O12 （CCTO） ceramics doped with Zr^4＋ were prepared. Effects of Zr^4＋ on microstructure, dielectric properties and conduction behavior of CaCaCu3Ti4O12 （x=0, 0.05, 0.10, 0.20） ceramics were studied in the frequency range of 10-10^6 Hz. Grain size and dielectric loss of Zr^4＋-doped CCTO ceramic decreased compared with pure CCTO. The loss tangent （tang） of CaCu3Ti4O12 （x=0.20） ceramic droped to 0.05 at a frequency of 1 kHz, which was reduced by 55% compared with pure CCTO ceramic. The mechanism effect of electrical conductivity on dielectric loss of ZP^4＋-doping CCTO ceramics was also discussed.展开更多
CaCu3Ti4O12 ceramic with a giant dielectric constant was synthesized by sol-gel method and sintered in three different sintering conditions： 1 035 ℃ for 48 h, 1 080 ℃ for 3 h and 48 h. The phase of the ceramics, th...CaCu3Ti4O12 ceramic with a giant dielectric constant was synthesized by sol-gel method and sintered in three different sintering conditions： 1 035 ℃ for 48 h, 1 080 ℃ for 3 h and 48 h. The phase of the ceramics, the element distribution, the valance state of Ti ions at grain boundaries, and the electrical properties were characterized via X-ray diffraction（XRD）, energy dispersive X-ray analysis（EDAX）, X-ray photoelectron spectroscopy（XPS）, electrical conduction and dielectric measurement. The results demonstrate that the grain-boundary microstructure and the electrical properties are influenced by sintering conditions： 1 By raising sintering temperature, the Cu-rich and Ti-poor grain boundary was formed and grain resistivity was decreased. 2 By prolonging sintering time, the content of Ti3＋ near the grain boundary increased, leading to the decrease of the grain-boundary resistivity and the increase of the activation energy at grain boundary. The ceramic, sintering at 1 080 ℃ for 48 h, exhibited a small grain resistivity（60.5 ＊cm）, a large grain-boundary activation energy（0.42 e V）, and a significantly enhanced dielectric constant（close to 1×105 at a low frequency of 1×103 Hz）. The results of electrical properties accord with the internal boundary layer capacitor model for explaining the giant dielectric constant observed in Ca Cu3Ti4O12 ceramics.展开更多
CaCu3Ti4O12 ceramics substituted by Mg for Ca were prepared by the solid state reaction method. The crystal structures, microstructures, and dielectric properties of the Ca1-xMgxCu3Ti4O12 ceramics were investigated. A...CaCu3Ti4O12 ceramics substituted by Mg for Ca were prepared by the solid state reaction method. The crystal structures, microstructures, and dielectric properties of the Ca1-xMgxCu3Ti4O12 ceramics were investigated. At lower doping concentrations, the substitution of Mg for Ca caused a decreased lattice constant, while at higher doping concentrations, some of the Mg dopants started to replace Ti and resulted in an increased lattice constant, and some could also replace Cu due to the similar ion radius between Mg and Cu ions. Mg doping was found to promote the grain growth of Ca1-xMgxCu3Ti4O12 ceramics during sintering. Grain boundary resistance of the Ca1-xMgxCu3Ti4O12 ceramics was found to be increased by Mg doping. Enhanced dielectric properties was observed in the Ca1-xMgxCu3Ti4O12 ceramics with x=0.05 for the frequency range from i kHz to 20 kHz. For other doping concentrations, the dielectric losses of Ca1-xMgxCu3Ti4O12 ceramics were generally lowered.展开更多
基金Funded by the Project of Sooc how University(Q3109909)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘CaCu3Ti4O12 （CCTO） ceramics doped with Zr^4＋ were prepared. Effects of Zr^4＋ on microstructure, dielectric properties and conduction behavior of CaCaCu3Ti4O12 （x=0, 0.05, 0.10, 0.20） ceramics were studied in the frequency range of 10-10^6 Hz. Grain size and dielectric loss of Zr^4＋-doped CCTO ceramic decreased compared with pure CCTO. The loss tangent （tang） of CaCu3Ti4O12 （x=0.20） ceramic droped to 0.05 at a frequency of 1 kHz, which was reduced by 55% compared with pure CCTO ceramic. The mechanism effect of electrical conductivity on dielectric loss of ZP^4＋-doping CCTO ceramics was also discussed.
基金Supported by the National Natural Science Foundation of China(51172166)the Ph.D.Programs Foundation of City College,Wuhan University of Science and Technology(2014CYBSKY003)
文摘CaCu3Ti4O12 ceramic with a giant dielectric constant was synthesized by sol-gel method and sintered in three different sintering conditions： 1 035 ℃ for 48 h, 1 080 ℃ for 3 h and 48 h. The phase of the ceramics, the element distribution, the valance state of Ti ions at grain boundaries, and the electrical properties were characterized via X-ray diffraction（XRD）, energy dispersive X-ray analysis（EDAX）, X-ray photoelectron spectroscopy（XPS）, electrical conduction and dielectric measurement. The results demonstrate that the grain-boundary microstructure and the electrical properties are influenced by sintering conditions： 1 By raising sintering temperature, the Cu-rich and Ti-poor grain boundary was formed and grain resistivity was decreased. 2 By prolonging sintering time, the content of Ti3＋ near the grain boundary increased, leading to the decrease of the grain-boundary resistivity and the increase of the activation energy at grain boundary. The ceramic, sintering at 1 080 ℃ for 48 h, exhibited a small grain resistivity（60.5 ＊cm）, a large grain-boundary activation energy（0.42 e V）, and a significantly enhanced dielectric constant（close to 1×105 at a low frequency of 1×103 Hz）. The results of electrical properties accord with the internal boundary layer capacitor model for explaining the giant dielectric constant observed in Ca Cu3Ti4O12 ceramics.
基金supported by the National Natural Science Foundation of China (Grant Nos.60661001,60844008)the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0730)the Program for Innovative Research Team of Nanchang University
文摘CaCu3Ti4O12 ceramics substituted by Mg for Ca were prepared by the solid state reaction method. The crystal structures, microstructures, and dielectric properties of the Ca1-xMgxCu3Ti4O12 ceramics were investigated. At lower doping concentrations, the substitution of Mg for Ca caused a decreased lattice constant, while at higher doping concentrations, some of the Mg dopants started to replace Ti and resulted in an increased lattice constant, and some could also replace Cu due to the similar ion radius between Mg and Cu ions. Mg doping was found to promote the grain growth of Ca1-xMgxCu3Ti4O12 ceramics during sintering. Grain boundary resistance of the Ca1-xMgxCu3Ti4O12 ceramics was found to be increased by Mg doping. Enhanced dielectric properties was observed in the Ca1-xMgxCu3Ti4O12 ceramics with x=0.05 for the frequency range from i kHz to 20 kHz. For other doping concentrations, the dielectric losses of Ca1-xMgxCu3Ti4O12 ceramics were generally lowered.
