Corundum-to-spinel structural phase transformation in alumina
Corundum-to-spinel structural phase transformation in alumina
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DOI：
10.1016/j.nimb.2015.06.005
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发表时间：
2015-09-01
影响因子：
1.3
通讯作者：
Alves, Eduardo
中科院分区：
文献类型：
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作者：
Adachi, Shogo;Ishimaru, Manabu;Alves, Eduardo
氧化铝（Al 2 O3）中存在多种多晶型物，它们在热退火时转变为具有六方晶系结构的稳定的α相。这种结构变化作为温度的函数是不可逆的，并且从未通过热处理观察到过α-Al 2 O3向另一种亚稳晶相的转变。在这项研究中，我们照射单晶的Al 2 O3与Zr离子，并获得了照射的微观结构组成的掩埋的α-Al 2 O3层包围在顶部和底部的层的缺陷立方尖晶石Al 2 O3相。我们研究了这种微结构的热稳定性，使用透射电子显微镜和X射线衍射。我们发现，在1173 K下退火1小时后，尖晶石相完全转变为尖晶石相：热处理后，介稳相转变为亚稳相。我们讨论这种不寻常的结构变化的背景下，我们的结果以及以前的观察。(C)2015 Elsevier B. V.版权所有。
Several polymorphs exist in alumina (Al2O3), and they transform to a stable cc-phase with a hexagonal corundum structure on thermal annealing. This structural change is irreversible as a function of temperature, and transformation of corundum to another metastable crystalline phase has never been observed by heat treatments. In this study, we irradiated single crystals of Al2O3 with Zr ions and obtained an irradiated microstructure consisting of a buried alpha-Al2O3 layer surrounded on top and bottom by layers of a defect cubic spinel Al2O3 phase. We examined the thermal stability of this microstructure using transmission electron microscopy and X-ray diffraction. We found that the corundum phase completely transforms to the spinel phase following annealing at 1173 K for 1 h: the thermodynamically stable phase transforms to the metastable phase by heat treatments. We discuss this unusual structural change within the context of our results as well as previous observations. (C) 2015 Elsevier B.V. All rights reserved.