Iodine Atom Diffusion in SiC and Zirconium with First-Principles Calculations
Iodine Atom Diffusion in SiC and Zirconium with First-Principles Calculations
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DOI：
10.13182/nt15-109
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发表时间：
2016-08
影响因子：
1.5
通讯作者：
Ruixuan Han;Liucheng Liu;Rui Tu;W. Xiao;Yingying Li;Huailin Li;Dan Shao
中科院分区：
文献类型：
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作者：
Ruixuan Han;Liucheng Liu;Rui Tu;W. Xiao;Yingying Li;Huailin Li;Dan Shao
用第一性原理计算和微动弹性带方法计算了碘原子在块体β-SiC和α-Zr中的间隙组态和扩散。块体碳化硅(SIC)中I间隙的形成能比块体Zr中I间隙的形成能高10倍。与在块体中掺杂相比，I间隙很难引入到块体碳化硅中。I原子在碳化硅和锆中的扩散机制为交换机制。碘在块体碳化硅中的扩散大致是一个各向同性的过程，其扩散势垒为1.2 eV，扩散尝试频率Γ0=25.12太赫兹。同时，I在块体中的间隙扩散是一个各向异性的过程。I间隙原子主要沿扩散势垒为0.16 eV、扩散尝试频率Γ0=2.88THz的Z字形路径在两个[0001]层之间扩散。总的来说，在290~3000K温度范围内，I间隙在块体碳化硅中的扩散速率低于在块体中的扩散速率。缺陷对I扩散的影响是一个值得进一步研究的课题。
Abstract Iodine atom interstitial configurations and diffusion in bulk β-SiC and α-Zr are calculated using first-principles calculations and the nudged elastic band method. The formation energy of an I interstitial in bulk silicon carbide (SiC) is ten times higher than that of an I interstitial in bulk Zr. The I interstitial is very difficult to introduce into bulk SiC compared with the doping process in bulk Zr. The diffusion mechanisms of an I atom in SiC and Zr are exchange mechanisms. Iodine interstitial diffusion in bulk SiC is roughly an isotropic process along a path that is a series of combinations of ISi → Ic and Ic → ISi, with a diffusion barrier of 1.20 eV and an attempt-to-diffuse frequency Γ0 = 25.12 THz. Meanwhile, I interstitial diffusion in bulk Zr is an anisotropic process. An I interstitial atom diffuses mainly between two Zr atom [0001] layers along a zigzag path with a diffusion barrier of 0.16 eV and an attempt-to-diffuse frequency Γ0 = 2.88 THz. In general, the diffusion rate of an I interstitial in bulk SiC is lower than that in bulk Zr in the temperature range from 290 to 3000 K. The defect effect on I diffusion is an interesting topic for future study.