Polaron relaxation and non-ohmic behavior in CaCu₃Ti₄O₁₂ ceramics with different cooling methods

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• 作者：Laijun Liu ; ^{ljliu2@163.com} ; Danping Shi ; Shaoying Zheng ; Yanmin Huang ; ShuangShuang Wu ; Yunhua Li ; Liang Fang ; Changzheng Hu
• 关键词：A. Ceramics ; D. Defects ; D. Thermal conductivity ; D. Electrical properties
• 刊名：Materials Chemistry and Physics
• 出版年：2013
• 出版时间：15 May, 2013
• 年：2013
• 卷：139
• 期：2-3
• 页码：844-850
• 全文大小：1943 K

文摘

Structure, defects, non-ohmic behavior and dielectric properties of CaCu₃Ti₄O₁₂ (CCTO) ceramics with furnace-cooled and water-quenched methods have been systemically investigated. Cooling methods make an influence on reoxidation process and cause changes of electric properties in grains and at grain boundaries. SEM-EDS provides detailed imaging information about Cu-rich phase on the fracture of CCTO ceramics which is explained by the reoxidation reaction during cooling. Morphologies of the water-quenched sample show very small grains floating in bigger grains; whereas they reveal that many grains are surrounded by an exfoliated sheet of Cu-rich phases in the furnace-cooled sample. The polaron relaxation associated with Ti³⁺ ions and oxygen vacancies occurs at low temperatures, and more Ti³⁺ ions are remained in the water-quenched sample. The Schottky barrier height (I-V, non-ohmic behavior) associated with the reoxidation of grain boundaries can be modified by cooling method.