The electrode/sample contact effects on the dielectric properties of the CaCu3Ti4O12 ceramic |
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| Affiliation: | 1. Department of Mechanical and Electronic Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333403, China;2. State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China;3. School of Materials Science and Engineering, University of Jinan, Jinan 250022, China;4. Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada;1. Integrated Nanotechnology Research Center (INRC), Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand;2. National Metal and Materials Technology Center, National Science and Technology Development Agency, Thailand Science Park, Pathumthani 12120, Thailand;3. Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002, Thailand;4. Thailand Center of Excellence in Physics, Commission on Higher Education, Bangkok 10400, Thailand;5. School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand;1. College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan, 030024, PR China;2. College of Physics and Electrical Engineering, Anyang Normal University, Anyang, 455000, PR China;1. School of Information Science and Technology, Northwest University, Xi’an, 710127, China;2. School of Chemistry and Materials, Northwest University, Xi’an, 710127, China;3. Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA |
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| Abstract: | In this paper, the contact effects at the electrode/sample interfaces on the dielectric properties of the CaCu3Ti4O12 (CCTO) ceramic were studied. The experimental results provide clear evidence that the colossal dielectric constant in CCTO is related to the ceramic itself; however, it may also partly originated from the electrode/sample contact effects which depends on the surface resistivity of the sample. When the surface resistivity of the ceramic is as high as 1.2 × 108 Ω cm, no obvious mobile space charges can be observed, and the dielectric properties of the sample is inert to the different metal electrodes and various sample thicknesses, indicating the colossal dielectric constant (near 2000 at 10 kHz) at room temperature is due to the true properties of the ceramic itself. However, after the surface resistivity is lowered to 3.1 × 107 Ω cm through post-annealing the sample in N2 atmosphere at 750 °C, obvious mobile space charges can be observed, and the dielectric properties of the sample become sensitive to the different types of contacts. The dielectric constant of the sample with Pt electrode shows a significant enhancement (up to 5000 at 10 kHz), comparing with that of the sample with Ag electrode. Clearly, in this case, the extrinsic contact contributes partly to the colossal dielectric constant of CCTO ceramic. |
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