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首页> 外文期刊>Separation and Purification Technology >Determination of the oxygen ion diffusion coefficients in mixed conductors by the volumetric measurement of the reoxidation kinetics
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Determination of the oxygen ion diffusion coefficients in mixed conductors by the volumetric measurement of the reoxidation kinetics

机译：通过再氧化动力学的体积测量确定混合导体中氧离子的扩散系数

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摘要

Mixed conducting ceramics 9ionic and electronic conducting oxides) have a high aplication potential for the oxygen separation from oxygen containing gas mixtures (mostly air). Because the ion diffusion controls frequently the rate of the total permeation flux, a simple and fast detrmination of the oxygen diffusion doefficients is the rerequisite for an efficient material screening. in this work, the volumetric measurement of the reoxidation of chemically reduced mixed conductors was used for the determination of oxygen ion diffusion coefficients. The described method has advantages compared to the frequently used mass relaxation technique, e.g. a hihger measuring effect, the suitability for fast processes (by use of large sampels) and a high resistance to abrupt pressure changes. The checkup of the measurement method on the reference materials SrFe_(1-x)Co_xO_z (x=0.6) and La_(0.79)MnO_(3+z) indicates a surfficient agreement with previous published values. the experimental results show a high internal consistency, as it is essential for a screening method. Diffusion coefficients are independently on the oxygen concentration over a wide range of the oxygen stoichiometry for all tested materials. Low activation energies in the range 0.10-0.5 eV were found. these latter results are opposed to the majority of publications on maixed conducting oxides. Additionally, new promising perovskite compositions in the system Sr_(1-x)ca_xMn_(1-y)O_(3-z) were presented.
机译：混合导电陶瓷（离子和电子导电氧化物）具有从含氧气体混合物（主要是空气）中分离氧气的高应用潜力。因为离子扩散频繁地控制总渗透通量的速率，所以氧扩散效率的简单而快速的脱除是有效材料筛选的必要条件。在这项工作中，化学还原的混合导体的再氧化的体积测量用于确定氧离子扩散系数。与经常使用的质量松弛技术（例如，质量分析）相比，所描述的方法具有优势。更高的测量效果，适用于快速过程（通过使用大型样品）以及对突然压力变化的高抵抗力。对参考材料SrFe_（1-x）Co_xO_z（x = 0.6）和La_（0.79）MnO_（3 + z）的测量方法的检查表明与先前公布的值有足够的一致性。实验结果显示出很高的内部一致性，这对于筛选方法至关重要。对于所有测试材料，扩散系数均取决于氧气化学计量范围内的氧气浓度。发现在0.10-0.5eV范围内的低活化能。后一结果与大多数有关混合氧化物的出版物相反。此外，提出了系统Sr_（1-x）ca_xMn_（1-y）O_（3-z）中新的有前途的钙钛矿成分。

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