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首页> 外文会议>International Workshop on Ceramic Interfaces; 19980916-19980919; Taejon; KR >Material Transport via the Grain Boundary of Lanthanum Chromites
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Material Transport via the Grain Boundary of Lanthanum Chromites

机译：通过铬铁矿晶粒边界的物质传输

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摘要

Material transport in alkaline-earth substituted lanthanum chromites is discussed. Diffusion coefficients of oxide ion and cations in alkaline-earths doped lanthanum chromites were determined by secondary ion mass spectrometry (SIMS). The contribution of grain boundary as a fast diffusion path was quantitatively evaluated by analysing the depth profiles. The grain boundary diffusion coefficients were 10~4 times higher than bulk diffusion coefficients for oxide ion, and 10~5 times higher for cations. For Sr-Ca interdiffusion, the diffusion mechanism at grain boundary has been found to be closely related to the valence state of chromium ion, which will play a main role of determining the vacancy concentration at A-site in the vicinity of grain boundaries. The oxygen partial pressure dependence of oxide ion diffusion coefficient was determined by annealing in Ar-~(18)O_2 and Ar-H_2-C~(18)O_2, and the results revealed good agreement with the data of oxygen permeation fluxes which were measured in a steady state under a large gradient of oxygen partial pressure. The effect of grain boundary diffusion was observed only in the oxidizing atmosphere, and bulk diffusion is dominant in the reducing atmosphere.
机译：讨论了碱土取代亚铬酸镧中的物质迁移。通过二次离子质谱法（SIMS）测定了碱土掺杂亚铬酸镧中的氧离子和阳离子的扩散系数。通过分析深度剖面，定量评估了作为快速扩散路径的晶界的贡献。晶界扩散系数比氧化物离子的体积扩散系数高10〜4倍，而对阳离子则高10〜5倍。对于Sr-Ca相互扩散，已发现晶界处的扩散机理与铬离子的价态密切相关，这将对确定晶界附近A位的空位浓度起主要作用。通过在Ar-〜（18）O_2和Ar-H_2-C〜（18）O_2中进行退火确定了氧离子扩散系数的氧分压依赖性，其结果与测得的氧渗透通量数据吻合良好在大的氧气分压梯度下处于稳定状态。仅在氧化气氛中观察到晶界扩散的影响，而在还原气氛中主体扩散占主导。

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