Effects of Cu stoichiometry on the micro structures, barrier-layer structures, electrical conduction, dielectric responses, and stability of CaCu3Ti4O12
Effects of Cu stoichiometry on the micro structures, barrier-layer structures, electrical conduction, dielectric responses, and stability of CaCu3Ti4O12
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DOI：
10.1016/j.actamat.2006.02.037
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发表时间：
2006-06-01
期刊：
影响因子：
9.4
通讯作者：
Ho, Hei-Fong
中科院分区：
文献类型：
--
作者：
Fang, Tsang-Tse;Mei, Li-Then;Ho, Hei-Fong
用X射线光电子能谱测定了CaCu3Ti4O12(CCTO)中Cu3+离子的存在，证实了CCTO的缺铜现象。Cu2+和Cu3+之间的电子跃迁被认为是CCTO半导体性质的根源。提出了一种新的CCTO模型，认为缺铜是形成势垒结构的基础。研究发现，致密化速率的提高、晶界不连续长大的发生和晶界电阻率的增大都与晶界上存在的铜离子有关。对于CaCu2.9Ti4O12样品，较低的介电常数可归因于较小的晶界面积和较难在细晶内发育或磁畴。CaCu(2.9)、Tri(4)O(12)和CaCu3.1Ti4O12的介电响应也可以用砖层模型来描述。最后，发现CCTO是不稳定的，并逐渐分解。(C)2006 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The presence of Cu3+ ions in CaCu3Ti4O12 (CCTO) has been determined using X-ray photoelectron spectroscopy and the Cu deficiency of CCTO confirmed. Electron hopping between Cu2+ and Cu3+ is proposed as the origin of the semiconducting nature of CCTO. A new model of CCTO with Cu deficiency being fundamental for the development of a barrier-layer structure is proposed. The enhancement of the densification rate, the occurrence of discontinuous grain growth, and the increase of grain boundary resistivity are found to be related to the presence of Cu ions at grain boundaries. For samples of CaCu2.9Ti4O12, the lower dielectric constant can be attributed to the smaller grain boundary areas and the difficulty in the development or domains inside the fine grains. The dielectric responses of CaCu(2.9)Tri(4)O(12) and CaCu3.1Ti4O12 can also be described using a brick-layer model. Finally, CCTO is found to be unstable and gradually decomposes. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.