Point defects production and energy thresholds for displacements in crystalline and amorphous SiC
Point defects production and energy thresholds for displacements in crystalline and amorphous SiC
复制标题
DOI：
10.1016/j.commatsci.2018.04.063
复制
发表时间：
2018-08
影响因子：
3.3
通讯作者：
B. Cowen;M. El-Genk
中科院分区：
文献类型：
--
作者：
B. Cowen;M. El-Genk
利用Tersoff + ZBL电位进行了分子动力学（MD）模拟，以确定能量高达400 eV的3C-SiC和非晶SiC （a-SiC）中碳和硅初级撞击原子（PKAs）产生点缺陷的阈值位移能（TDEs）的方向依赖性。这些材料正在考虑作为下一代轻水核反应堆的耐事故包层材料，并正在许多其他工业应用中使用。结果表明，在3C-SiC中PKA或原子位移的tde和Frenkel对产生的tde是不同的，具有高度的各向异性。在任何晶体学方向上产生碳空位的最低能量分别为14-16 eV和38-58 eV。C和Si pka产生Si空位的最低能量分别为59-71 eV和42-46 eV。400 eV C PKA和Si PKA产生的C空位数分别是硅空位数的4倍和1.75倍。在a-SiC中，Si PKAs和原子位移的TDE概率分布不同，但C PKAs的TDE概率分布相似。Si PKA可能以低于取代Si PKA所需的能量取代质量较小的C原子，类似于3C-SiC中某些方向的相互作用序列。在3C-SiC（26 eV）中引起C- PKA位移的能量为50%，是a- sic（13 eV）的两倍多。对于Si pka，这些能量分别为48 eV和27 eV。测定的tde与报道的实验值和基于MD模拟的结果一致，可用于未来辐照效应的研究。
Molecular dynamics (MD) simulations are performed using the Tersoff + ZBL potential to determine the values and directional dependence of the threshold displacement energies (TDEs) for the production of point defects by carbon and silicon primary knock-on atoms (PKAs) with energies up to 400 eV in 3C-SiC and amorphous SiC (a-SiC). These materials are being considered for accident tolerant cladding materials in next generation light-water nuclear reactors and are being used in many other industrial applications. Results show that the TDEs for the displacement of a PKA or an atom in 3C-SiC, as well as those for the production of a Frenkel pair are different and highly anisotropic. The lowest energy to produce a carbon vacancy in any crystallographic direction is 14–16 eV and 38–58 eV for the C and Si PKAs, respectively. The lowest energies for the C and Si PKAs to produce a Si vacancy are 59–71 eV and 42–46 eV, respectively. The number of C vacancies produced by 400 eV C PKA and Si PKA are 4x and 1.75x the silicon vacancies produced, respectively. In a-SiC, the TDE probability distributions for the displacement of Si PKAs and of an atom differ, but are similar for C PKAs. The Si PKAs are likely to displace the less-massive C atoms at energies lower than that required to displace a Si PKA, resembling the interaction sequences in some directions in 3C-SiC. The energy to cause a C PKA displacement with 50% probability in 3C-SiC (26 eV), is more than twice that in a-SiC (13 eV). For the Si PKAs, these energies are 48 eV and 27 eV, respectively. The determined TDEs, which are consistent with the reported experimental values and those based on MD simulations, could be used in future investigations of irradiation effects.