Spectroscopic study of the discoloration of transparent MgAl2O4 spinel fabricated by spark-plasma-sintering (SPS) processing
Spectroscopic study of the discoloration of transparent MgAl2O4 spinel fabricated by spark-plasma-sintering (SPS) processing
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DOI：
10.1016/j.actamat.2014.10.030
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发表时间：
2015-02-01
期刊：
影响因子：
9.4
通讯作者：
Sakka, Yoshio
中科院分区：
文献类型：
--
作者：
Morita, Koji;Kim, Byung-Nam;Sakka, Yoshio
通过光谱技术和透射电子显微镜研究了火花等离子体烧结尖晶石的变色。变色的原因是碳污染和晶格缺陷（色心）的结合，这些缺陷根据火花等离子体烧结条件引入到尖晶石基体中。对于 = 50 摄氏度 min(-1) 的低加热速率，在加热过程中由于碳相从碳纸和石墨模具中蒸发而发生额外的碳污染，并且随着加热速率的增加而加剧。目前的数据表明，色心（F+-中心）可能是通过氧空位的形成而产生的，氧空位主要是由位错运动引入的，具体取决于烧结条件。由于烧结速率，即变形速率，随着加热速率的增加而增加，因此位错相关色心的浓度随着加热速率的增加而增加，但由于氧空位的漂白而随着烧结温度的增加而降低。对于本尖晶石，根据烧结条件，由于碳污染和F+中心的形成而导致的变色会降低透光率。 (C) 2014 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
Discoloration of spark-plasma-sintered spinel was investigated by spectroscopic techniques and transmission electron microscopy. The discoloration is explained by the combination of carbon contaminations and lattice defects (color centers), which are introduced in the spinel matrix depending on the spark-plasma-sintering conditions. For low heating rates of = 50 degrees C min(-1), additional carbon contamination occurred by evaporating the carbon phases from the carbon papers and graphite dies during the heating process, and tended to be enhanced by the increasing heating rate. The present data indicate that the color center (F+-center) may be generated by the formation of oxygen vacancies, which are mainly introduced by dislocation motion depending on the sintering conditions. Since the rate of sintering, namely the deformation rate, increased with the heating rate, the concentration of the dislocation-related color centers increased with the heating rate, but decreased with the sintering temperature due to the bleaching of the oxygen vacancies. For the present spinel, the discoloration due to the carbon contamination and the formation of F+-centers deteriorates the light transmission, depending on the sintering conditions. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.