Influence of microstructure on oxide ionic conductivity in doped CeO2 electrolytes
Influence of microstructure on oxide ionic conductivity in doped CeO2 electrolytes
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DOI：
10.1007/s10832-006-6311-7
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发表时间：
2006
影响因子：
1.7
通讯作者：
T. Mori;J. Drennan
中科院分区：
文献类型：
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作者：
T. Mori;J. Drennan
掺杂的二氧化铈（CeO 2）化合物是萤石型氧化物，其在氧化气氛中显示出比氧化钇稳定的氧化锆更高的氧化物离子电导率。因此，对这些材料在固体氧化物燃料电池（SOFC）的“低温（500 ℃-650 ℃）"操作中的应用表现出相当大的兴趣。在这项研究中，一些稀土（如。采用碳酸盐共沉淀法合成了Gd、Sm和Dy掺杂的CeO 2纳米粉体。萤石型固溶体能够在低温（例如400 ℃）下形成，并且随后通过常规烧结（CS）方法在1000 ℃至1450 ℃的温度范围内制造致密的烧结体。为了开发高质量的固体电解质，这些掺杂CeO 2固体电解质的微观结构在原子水平上进行了研究，使用透射电子显微镜（TEM）。通过CS获得的试样具有连续且大的微畴，每个晶粒内具有扭曲的烧绿石结构或相关结构。我们的结论是，在这些掺杂CeO 2系统的导电性能的强烈影响的晶粒中的微畴尺寸。为了使微区尺寸最小化，检查放电等离子体烧结（SPS）。SPS还没有被用来制造致密的烧结体掺杂CeO 2电解质，以前，从石墨模具的碳渗透的标本，抑制致密化。为了克服这一挑战，并能够生产致密的烧结体的掺杂CeO 2的晶粒尺寸，最大限度地减少微区生长，SPS和CS方法的组合进行了检查。使用这种结合的方法，我们报告说，我们能够生产出完全致密的试样，提高导电性。这与微区尺寸的减小相关。因此，我们得出结论，晶粒结构内的微畴尺寸的控制是成功设计具有改善的导电性的电解质材料的关键组成部分。
Doped ceria (CeO2) compounds are fluorite type oxides, which show oxide ionic conductivity higher than yttria stabilized zirconia, in oxidizing atmospheres. As a consequence of this, considerable interest has been shown in application of these materials for `low (500∘–650∘C)’ temperature operation of solid oxide fuel cells (SOFCs). In this study, some rare earth (eg. Gd, Sm, and Dy) doped CeO2nano-powders were synthesized via a carbonate co-precipitation method. Fluorite-type solid solution were able to be formed at low temperature, such as 400∘C and dense sintered bodies were subsequently fabricated in the temperature ranging from 1000∘to 1450∘C by conventional sintering (CS) method. To develop high quality solid electrolytes, the microstructure at the atomic level of these doped CeO2solid electrolytes were examined using transmission electron microscopy (TEM). The specimens obtained by CS had continuous and large micro-domains with a distorted pyrochlore structure or related structure, within each grain. We conclude that the conducting properties in these doped CeO2systems are strongly influenced by the micro-domain size in the grain. To minimize the micro-domain size, spark plasma sintering (SPS) was examined. SPS has not been used to fabricate dense sintered bodies of doped CeO2electrolytes, previously; carbon from the graphite dies penetrates the specimens and inhibits densification. To overcome this challenge, and to be able to produce dense sintered bodies of doped CeO2of a grain size that minimizes the microdomain growth, a combination of SPS and CS methods were examined. Using this combined method we report that we were able to produce fully dense specimens with improved conductivity. This is correlated with a reduction in the size of the micro-domains. Consequently we conclude that the control of micro-domain size within the grain structure is a key component in the successful design of electrolyte materials with improved conductivity.