Quantitative evaluation of hydrogen atoms trapped at single vacancies in tungsten using positron annihilation lifetime measurements: Experiments and theoretical calculations
Quantitative evaluation of hydrogen atoms trapped at single vacancies in tungsten using positron annihilation lifetime measurements: Experiments and theoretical calculations
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DOI：
10.1016/j.jnucmat.2017.09.002
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发表时间：
2017-12
影响因子：
3.1
通讯作者：
Koichi Sato;A. Hirosako;K. Ishibashi;Yuto Miura;Qiu Xu;Masahira Onoue;Y. Fukutoku;T. Onitsuka-
中科院分区：
文献类型：
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作者：
Koichi Sato;A. Hirosako;K. Ishibashi;Yuto Miura;Qiu Xu;Masahira Onoue;Y. Fukutoku;T. Onitsuka-
通过测量钨中含氢原子空位的正电子湮灭寿命（PAL），研究了其变化。利用电子辐照引入空位，在高压氢气气氛（5.8 MPa）下对氢原子进行带电。单空位的PAL约为175 ps，充氢后PAL降至155 ps左右。利用第一性原理计算得到的电子密度计算了含氢原子的单空位的PAL。通过实验测量和模拟计算了含氢原子空位的PAL变化，并对两者进行了比较。发现一个空位捕获一个或两个氢原子（平均1.6个原子）。在热平衡态假设下，得到了氢对空位的结合能为1.19 eV，略高于前人的研究结果（1.06 eV）。据信是杂质的影响导致了这种差异。阐明了杂质对PAL和结合能变化的影响，使得对被困在单个空位上的氢原子的定量评价更加准确。
The change in the positron annihilation lifetime (PAL) of vacancies containing hydrogen atoms was investigated by taking PAL measurements in tungsten. The vacancies were introduced by electron irradiation, and hydrogen atoms were charged under a high-pressure hydrogen atmosphere (5.8 MPa). The PAL of single vacancies was measured to be approximately 175 ps, which decreased to approximately 155 ps after hydrogen charging. The PAL of single vacancies containing hydrogen atoms was calculated using the electron density obtained by a first principles calculation. The change in the PAL of vacancies containing hydrogen atoms was measured in experiments and calculated in simulations, and then, the two values were compared. It was found that one vacancy captured one or two hydrogen atoms (an average of 1.6 atoms). The binding energy of hydrogen to vacancies of 1.19 eV was obtained under the assumption of a thermal equilibrium state, which was slightly higher than the value determined by a previous study (1.06 eV). It is believed that the effect of impurities causes this discrepancy. The elucidation of the effect of impurities on the change in the PAL and the binding energy leads to greater accuracy in the quantitative evaluation of the hydrogen atoms trapped at single vacancies.