Grain Growth-Controlled Giant Permittivity in Soft Chemistry CaCu3Ti4O12 Ceramics
Grain Growth-Controlled Giant Permittivity in Soft Chemistry CaCu3Ti4O12 Ceramics
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DOI：
10.1111/j.1551-2916.2007.02174.x
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发表时间：
2008-02
影响因子：
3.9
通讯作者：
L. Marchin;S. Guillemet-Fritsch;B. Durand;A. Levchenko;A. Navrotsky;T. Lebey
中科院分区：
文献类型：
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作者：
L. Marchin;S. Guillemet-Fritsch;B. Durand;A. Levchenko;A. Navrotsky;T. Lebey
我们报告的介电常数高达5.4105，在室温和1 kHz的CaCu3Ti4O12（CTO）陶瓷，来自多相粉末（共沉淀产物），由“chimie douce”（共沉淀）的方法，然后在空气中烧结。烧结产物为纯相CTO陶瓷。高介电常数是通过调节晶粒尺寸和晶界厚度来实现的。通过在1和3.1重量%之间改变初始粉末（煅烧的共沉淀产物）中过量CuO的浓度来控制晶粒生长。纯CCTO陶瓷的介电常数随着CuO初始浓度的增加而增加，在CuO的2.4wt%时达到最大值。粉末中过量CuO的进一步增加导致介电常数降低，伴随着在烧结产品中形成单独的相CuO。不寻常的晶粒生长行为归因于初始粉末中存在的CuO和TiO 2之间的共晶反应。
We report a dielectric constant of up to 5.4105 at room temperature and 1 kHz for CaCu3Ti4O12 (CCTO) ceramics, derived from multiphase powders (coprecipitation products), made by a ‘‘chimie douce’’ (coprecipitation) method, and then sintered in air. The sintered products are pure-phase CCTO ceramics. The high dielectric constant is achieved by tuning the size of grains and the thickness of grain boundaries. The grain growth is controlled by varying the concentration of excess CuO in the initial powder (calcined coprecipitation products) between 1 and 3.1 wt%. The dielectric constant of pure CCTO ceramics increases with the initial CuO concentration, reaching its maximum at 2.4 wt% of CuO. A further increase of excess CuO in powders results in a permittivity decrease, accompanied by the formation of CuO as a separate phase in the sintered products. The unusual grain growth behavior is attributed to a eutectic reaction between CuO and TiO2 present in the initial powder.