期刊
CERAMICS INTERNATIONAL
卷 39, 期 7, 页码 7879-7889出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2013.03.049
关键词
Sol-gel processes; X-ray methods; Impedance; Dielectric properties
资金
- National Science Foundation of China (NSFC) [51172136, 51107077]
- Graduate Student Innovation Fund of Shaanxi Normal University [2012CXS028]
- Fundamental Research Funds for the Central Universities [GK201101004]
- Open Fund of Shaanxi Province Key Laboratory [2010SYS-07]
CaCu3Ti4O12 precursor powders were synthesized by the sol-gel process. The optimized processing parameters for the synthesis of precursor powders were as follows: the Ti concentration was 0.60 mol/L, the pH value of the sol was 1.58, and the aging time of the sol was 6 h. After sintering at 1100 degrees C for 15 h, the CCTO ceramics with the highest density and fine-grained microstructure were obtained, exhibiting outstanding dielectric properties: epsilon'approximate to 13.50 x 10(4) and tan delta=0.014 (at 1 kHz). The low dielectric loss was attributed to the highest grain boundary resistance which significantly reduced the leakage current across grain boundaries. A broad dielectric relaxation peak was observed around 300 degrees C. The complex impedance spectroscopy analysis suggested that the obtained CaCu3Ti4O12 ceramics were electrically heterogeneous, consisting of semiconducting grains and insulating grain boundaries. The calculated grain boundary resistance and grain resistance were 0.87 M Omega and 3.50 Omega, respectively. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
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