Temperature dependence of the radiation tolerance of nanocrystalline pyrochlores A2Ti2O7 (A = Gd, Ho and Lu)
Temperature dependence of the radiation tolerance of nanocrystalline pyrochlores A2Ti2O7 (A = Gd, Ho and Lu)
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纳米晶烧绿石 A2Ti2O7（A = Gd、Ho 和 Lu）的辐射耐受性与温度的关系
DOI：
10.1016/j.actamat.2016.03.025
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发表时间：
2016-05
期刊：
影响因子：
9.4
通讯作者：
Wang Y. Q.
中科院分区：
文献类型：
--
作者：
Wen J.;Sun C.;Dholabhai P. P.;Xia Y.;Tang M.;Chen D.;Yang D. Y.;Li Y. H.;Uberuaga B. P.;Wang Y. Q.
由于界面和表面的高密度，纳米晶体材料的潜在的抗辐射能力得到了极大的关注，这既是为了了解这些缺陷宿的基本作用，也是为了开发它们在高辐射环境中的应用。用1-MeV KR2+离子轰击方法研究了粒度为20-30 nm的A2Ti2O7(A=Gd，Ho，Lu)纳米焦绿石粉的辐照响应.在室温下，每种纳米晶化合物的临界非晶化通量都大于其粗晶化合物的临界非晶化通量，表明其抗非晶化能力增强.在480-600℃的高温下进行离子辐照，进一步研究了温度对其中一种化合物纳米晶Lu2Ti2O7的辐照响应的影响，发现纳米晶Lu2Ti2O7的临界非晶化温度(610K)明显高于其粗晶相(480KK)，表明纳米晶Lu2Ti2O7在高温下抗非晶化能力低于其粗晶相。我们借助原子模拟来解释这些结果。分子静力学计算发现，阳离子反位缺陷在近表面形成的能量成本低于在块体中形成的成本，这表明在低温下，这些材料的纳米晶形式通常比粗晶形式更不容易非晶化，在那里缺陷动力学可以忽略不计。相反，在高温下，由于纳米焦绿石中表面的凹陷特性，阳离子间隙对反位缺陷的退火率显著降低，这是纳米晶相比粗晶相的非晶化温度高的原因。综上所述，这些结果为纳米晶体材料在辐照下的行为提供了新的见解。
A potentially enhanced radiation resistance of nanocrystalline materials, as a consequence of the high density of interfaces and surfaces, has attracted much attention both to understand the fundamental role of these defect sinks and to develop them for high-radiation environments. Here, irradiation response of nanocrystalline A2Ti2O7(A = Gd, Ho and Lu) pyrochlore powders with grain sizes of 20–30 nm was investigated by 1-MeV Kr2+ion bombardment.In situtransmission electron microscopy (TEM) revealed that the critical amorphization fluence for each nanocrystalline compound at room temperature was greater than that for their coarse-grained counterparts, indicating an enhanced amorphization resistance. The effect of temperature on the irradiation response of one of these compounds, nanocrystalline Lu2Ti2O7, was further examined by performing ion irradiation at an elevated temperature range of 480–600 K. The critical amorphization temperature (Tc) was found to be noticeably higher in nanocrystalline Lu2Ti2O7(610 K) than its coarse-grained counterpart (480 K), revealing that nanocrystalline Lu2Ti2O7is less resistant to amorphization compared to its coarse-grained phase under high temperatures. We interpret these results with the aid of atomistic simulations. Molecular statics calculations find that cation antisite defects are less energetically costly to form near surfaces than in the bulk, suggesting that the nanocrystalline form of these materials is generally less susceptible to amorphization than coarse-grained counterparts at low temperatures where defect kinetics are negligible. In contrast, at high temperatures, the annealing efficiency of antisite defects by cation interstitials is significantly reduced due to the sink properties of the surfaces in the nanocrystalline pyrochlore, which contributes to the observed higher amorphization temperature in the nano-grained phase than in coarse-grained counterpart. Together, these results provide new insight into the behavior of nanocrystalline materials under irradiation.
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影响因子：
41.2
作者：
Sickafus, Kurt E.;Grimes, Robin W.;Uberuaga, Blas P.
通讯作者：
Uberuaga, Blas P.
DOI：
10.1557/proc-713-jj3.1
发表时间：
2002-04
期刊：
MRS Proceedings
影响因子：
--
作者：
W. J. Weber;R. Ewing;B. McGrail;G. Cragnolino
通讯作者：
W. J. Weber;R. Ewing;B. McGrail;G. Cragnolino
影响因子：
4.6
作者：
Chen, Di;Wang, Jing;Chen, Tianyi;Shao, Lin
通讯作者：
Shao, Lin
DOI：
10.1016/s0168-583x(98)00847-7
发表时间：
1999-01
影响因子：
1.3
作者：
S. X. Wang;Luming Wang;R. Ewing;G. Was;G. Lumpkin
通讯作者：
S. X. Wang;Luming Wang;R. Ewing;G. Was;G. Lumpkin
影响因子：
2.7
作者：
W. J. Weber;R. Ewing;Luming Wang
通讯作者：
W. J. Weber;R. Ewing;Luming Wang