Significantly enhanced breakdown field in Ca1-xSrxCu3Ti4O12 ceramics by tailoring donor densities |
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Authors: | Zhuang Tang Yuwei Huang Kangning Wu Jianying Li |
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Affiliation: | State Key Laboratory of Electrical Insulation and Power Equipment, Xi`an Jiaotong University, Xi`an, Shaanxi, 710049, China |
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Abstract: | Significantly enhanced breakdown field of 24.52 kV cm?1 as well as noteworthy nonlinear coefficient of 8.11 and low dielectric loss of 0.077 were obtained in Ca0.6Sr0.4Cu3Ti4O12 ceramic. It was proved from impedance spectra that improved breakdown field was attributed to enhanced grain boundary resistance and elevated Schottky barrier height, which was further found resulting from reduced donor densities in C-V measurements. In addition, it was found that the activation energy originated from oxygen vacancies was increased, indicating the generation of oxygen vacancies was suppressed. Since oxygen vacancies acted as donors in depletion layers, it is reasonable to deduce that the reduced donor density was mainly ascribed to the decreased oxygen vacancies. In conclusion, maximum integrated action of strong solid solution effect and weak Sr-stretching effect was achieved when Sr/Ca ratio is 40/60, leading to greatly elevated potential barrier height and enhanced breakdown field consequently. |
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Keywords: | CCTO ceramics Breakdown field Sr/Ca ratio Grain boundary Donor densities |
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