Density and structural effects in the radiation tolerance of TiO2 polymorphs
Density and structural effects in the radiation tolerance of TiO2 polymorphs
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DOI：
10.1088/0953-8984/25/35/355402
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发表时间：
2013-09
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影响因子：
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通讯作者：
M. Qin;E. Kuo;K. Whittle;S. Middleburgh;M. Robinson;N. Marks;G. Lumpkin
中科院分区：
文献类型：
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作者：
M. Qin;E. Kuo;K. Whittle;S. Middleburgh;M. Robinson;N. Marks;G. Lumpkin
用分子动力学方法研究了TiO2的辐射响应。模拟的动机是由实验观察，三个低压多晶型，金红石，板钛矿和金红石，表现出极大的不同的公差下的离子束照射的非晶化。为了理解结构的作用，我们使用小热峰方法进行了大量的模拟。我们量化到高的统计精度的缺陷数量作为温度和结构类型的函数，并再现实验观察到的所有主要趋势。为了评估一个假设，相对于非晶相的体积应变是一个重要的驱动力缺陷恢复，我们进行尖峰模拟，其中的晶体密度是在很宽的范围内变化。值得注意的是，一旦考虑到密度差异，多晶型物之间的巨大差异就消失了。这一发现表明，密度是一个重要的因素，控制在二氧化钛的辐射耐受性。
The radiation response of TiO2 has been studied using molecular dynamics. The simulations are motivated by experimental observations that the three low-pressure polymorphs, rutile, brookite and anatase, exhibit vastly different tolerances to amorphization under ion-beam irradiation. To understand the role of structure we perform large numbers of simulations using the small thermal spike method. We quantify to high statistical accuracy the number of defects created as a function of temperature and structure type, and reproduce all the main trends observed experimentally. To evaluate a hypothesis that volumetric strain relative to the amorphous phase is an important driving force for defect recovery, we perform spike simulations in which the crystalline density is varied over a wide range. Remarkably, the large differences between the polymorphs disappear once the density difference is taken into account. This finding demonstrates that density is an important factor which controls radiation tolerance in TiO2.