Hillocks created for amorphizable and non-amorphizable ceramics irradiated with swift heavy ions: TEM study
Hillocks created for amorphizable and non-amorphizable ceramics irradiated with swift heavy ions: TEM study
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为经快速重离子辐照的非晶化和非非晶化陶瓷而产生的小丘：TEM 研究
DOI：
10.1088/1361-6528/aa8778
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发表时间：
2017
期刊：
影响因子：
3.5
通讯作者：
Okubo N
中科院分区：
文献类型：
--
作者：
Ishikawa N;Taguchi T;Okubo N
在以前的研究中，我们发现，小丘（即表面离子轨道）可以成像使用透射电子显微镜（TEM）照射薄CeO2样品与快速重离子（SHI）在斜入射。本文用同样的透射电镜方法观察了Y3Fe5O12（YIG）和三种氟化物（CaF2，SrF2和BaF2）的电子束。对于YIG，这是一个amorphizable材料，小丘被发现具有非晶特征与离子径迹的非晶特征一致。对于氟化物，我们发现，小丘没有表现出非晶的功能，他们是由纳米方解石。尽管YIG和CaF2的小丘具有不同的结晶学特征，但小丘直径与两种材料的热峰模型预测的熔融区直径一致。据发现，对于YIG的小丘直径是可比的离子轨道直径，而氟化物，它总是大于离子轨道直径。结果表明，CaF2中离子径迹直径存在速度效应.同时发现，对于氟化物，离子丘和离子径迹的直径均按阳离子质量的顺序变化（即CaF2 <SrF2 <BaF2）。上述结果的小丘和离子径迹的SHI辐照氟化物可以一致的热峰模型的框架内解释，如果熔化和连续的再结晶假设。
In a previous study, we found that hillocks (ie surface ion tracks) can be imaged using transmission electron microscopy (TEM) by irradiating thin CeO 2 samples with swift heavy ions (SHI) at oblique incidence. In the present study, the same TEM method is applied to Y 3 Fe 5 O 12 (YIG) and three fluorides (CaF 2, SrF 2 and BaF 2) for observing hillocks. For YIG, which is one of the amorphizable materials, hillocks are found to have amorphous features consistent with amorphous features of ion tracks. For the fluorides, it is found that the hillocks do not exhibit amorphous features, and they are composed of nanocrystallites. Although hillocks for YIG and CaF 2 exhibit different crystallographic features, hillock diameter agrees with the molten region diameter predicted by the thermal spike model for both materials. It is found that for YIG the hillock diameter is comparable to the ion track diameter, whereas for the fluorides it is always larger than the ion track diameter. The present result shows the existence of the velocity effect for ion track diameter in CaF 2. It is also found that for fluorides both hillock and ion track diameters vary in the order of cation mass (ie CaF 2< SrF 2< BaF 2). The above results of hillocks and ion tracks for SHI-irradiated fluorides can be consistently interpreted within the framework of the thermal spike model, if melting and successive recrystallization are assumed.