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河北工业大学
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Structure and dielectric relaxations of CaCu3Ti4O12 ceramics by heat treatments in different atmospheres.

Title: Structure and dielectric relaxations of CaCu3Ti4O12 ceramics by heat treatments in different atmospheres.
Authors: Zhao, Xuetong1
Ren, Lulu1
Yang, Lijun1
Li, Shuai1
Liao, Ruijin1
Li, Weiwei2
Li, Jianying3
Source: IEEE Transactions on Dielectrics & Electrical Insulation. Apr2017, Vol. 24 Issue 2, p764-773. 10p.
Document Type: Article
Subject Terms: CERAMICS
EXPANSION of liquids
ELECTROMAGNETIC waves
HIGH temperatures
HEAT transfer
Author-Supplied Keywords: CaCu3Ti4O12 ceramics ; Decision support systems ; Dielectric behavior ; Electrical properties ; Hafnium ; Heat treatment ; Stored energy density
NAICS/Industry Codes: 327110 Pottery, Ceramics, and Plumbing Fixture Manufacturing
Abstract: CaCu3Ti4O12 (CCTO) ceramics have drawn much attention for their potential application in energy storage components and overvoltage protection devices. In order to improve the electrical properties and understand the colossal dielectric behavior, several CCTO ceramic samples were prepared and heat treated in different atmospheres. The results showed that the breakdown field and nonlinear coefficient were effectively intensified, and the dielectric loss was reduced after heat treatments in the oxidizing atmosphere including air and oxygen. However, CCTO phases will decompose into TiO2, CuO and CaTiO3 phases when heat treated in the neutral atmosphere such as nitrogen, losing its colossal dielectric behaviors and excellent electrical properties. It was found that the oxygen atmosphere played the most beneficial effect in improving the characteristics of CCTO ceramics in this research. The maximum stored energy density of CCTO can be promoted from 7.7 to 26.5 kJ/m3, and the barrier height between grain boundaries were increased from 0.46 to 0.62 eV which may be closely related with its high breakdown filed. Three dielectric relaxations were observed in CCTO ceramics. After heat treatment in oxygen atmosphere, the activation energies of the two relaxation peaks (peak 1 and peak 2) in high frequencies kept nearly constant, at 0.11 and 0.51 eV respectively, while the activation energy of relaxation peak 3 at low frequency were enhanced from 0.75 to 0.85 eV, which may be related to the oxygen vacancy defects. Moreover, the contribution of dc conductivity to dielectric loss can be effectively restrained. An equivalent circuit model was proposed according to impedance analysis to expound the correlation between electrical properties and dielectric relaxations. [ABSTRACT FROM AUTHOR]
(Copyright applies to all Abstracts.)
Author Affiliations: 1State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University Shapingba District, Shazheng Street No. 174, Chongqing, 400044, China ; 2State Grid Sichuan Electric Power Research Institute ; 3State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No.28, Xianning West Road, Xi'an, Shaanxi, 710049, China
ISSN: 1070-9878 (Sherpa/RoMEO, JCR)
PageCount: 764-774
volume: 24
issue: 2
issn: 10709878
pubdate: 2017
DOI: https://doi.org/10.1109/TDEI.2017.006278
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