Influence of Grain Size on Impedance Spectra and Resistance Degradation Behavior in Acceptor (Mg)‐Doped BaTiO3 Ceramics
Influence of Grain Size on Impedance Spectra and Resistance Degradation Behavior in Acceptor (Mg)‐Doped BaTiO3 Ceramics
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DOI：
10.1111/j.1551-2916.2009.03305.x
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发表时间：
2009-12
影响因子：
3.9
通讯作者：
S. Yoon;C. Randall;Kangheon Hur
中科院分区：
文献类型：
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作者：
S. Yoon;C. Randall;Kangheon Hur
对比了（Mg）掺杂BaTiO3中受主浓度对尺寸分别为1.90 μ m和1.08 μm的粗晶和细晶样品电阻退化行为的影响。这两种情况下表现出类似的趋势，退化的时间随着受体浓度的增加而系统地减少，但是对于给定的掺杂剂浓度，绝对速率非常不同。虽然晶粒尺寸和晶界是重要的，它也表明，通过阻抗分析，降解行为取决于晶粒的电导率（σg）和离子迁移数（tion）的评价由瓦尔堡阻抗。在相同名义受主浓度条件下，细晶样品的晶粒电导率（σg）远低于粗晶样品，而晶界电导率（σgb）与粗晶样品相差不大。离子迁移数（tion）也小得多，在细粒样品。这些结果表明，随着晶粒尺寸的减小，离子补偿增强氧空位的实际有效受主浓度变小。这一事实加上晶界数量的增加解释了随着晶粒尺寸的减小而改善的降解行为。
The effect of acceptor concentration in (Mg)-doped BaTiO3 on the resistance degradation behavior was contrasted between coarse- and fine-grain samples with ∼90 and ∼0.8 μm in size, respectively. Both cases showed similar trends that the time to degradation decreased systematically with the increase of acceptor concentration, however the absolute rates are very different for a given dopant concentration. Although the grain size and grain boundaries are important, it is also shown through an impedance analysis that the degradation behavior depends on the grain conductivity (σg) and ionic transference number (tion) as evaluated by the Warburg impedance. Under the condition of the same nominal acceptor concentration, fine-grain samples showed much lower grain conductivity (σg) but little differences in the grain boundary conductivity (σgb) than that of coarse-grain samples. The ionic transference number (tion) was also much smaller in fine-grain samples. These results show that the actual effective acceptor concentration on being ionically compensated to enhance oxygen vacancies becomes smaller with the decrease of grain size. This fact coupled to the increase of the number of grain boundaries accounts for the improved degradation behavior with the decrease of grain size.