Ⅰ. INTRODUCTION Critical current density J_c varies with structural imperfections in non-ideal type-Ⅱ superconductors, and it is sensitive to the defect concentration. Neutron irradiation has been established as a u...Ⅰ. INTRODUCTION Critical current density J_c varies with structural imperfections in non-ideal type-Ⅱ superconductors, and it is sensitive to the defect concentration. Neutron irradiation has been established as a useful tool to increase the defect concentration in superconducting materials. Many experiments have shown that neutron irradiation at a suitable fluence would展开更多
AL-6XN stainless steels, one of the candidate structure materials for supercritical water-cooled reactor, were irradiated from 0.5 to 5 dpa using 100 keV H2＋ ions at 290 and 380 ℃. Microstructures were characterized...AL-6XN stainless steels, one of the candidate structure materials for supercritical water-cooled reactor, were irradiated from 0.5 to 5 dpa using 100 keV H2＋ ions at 290 and 380 ℃. Microstructures were characterized by transmission electron microscopy （TEM）. Dislocation loops were the dominant radiation-induced defects. All the dislocation loops had 1/3 〈111〉 type Burgers vector. Number density and size of the loops have been measured. Nucleation and evolution of dislocation loops were also investigated. Voids were observed only in the condition of 5 dpa at 380 ℃. Different evolution mechanisms of the radiation-induced dislocation loops were discussed. Effects of hydrogen and elevated temperature on the microstructural evolution were also investigated. Besides, the formed voids have a further effect on the evolution of dislocation loops.展开更多
The strain and stress fields of a rectangular dislocation loop in an isotropic solid that is a semi-infinite medium (half medium) are developed here for a Volterra-type dislocation. Specifically, the loop is parallel ...The strain and stress fields of a rectangular dislocation loop in an isotropic solid that is a semi-infinite medium (half medium) are developed here for a Volterra-type dislocation. Specifically, the loop is parallel to the free surface of the solid. The elastic fields of the dislocation loop are developed by integrating the displacement equation of infinitesimals dislocation loops over a finite rectangular loop area below the free surface. The strains and stress then follow from the small strain tensor and Hooke’s law for isotropic materials, respectively. In this paper, analytical verification and numerical verification for the elastic fields are both demonstrated. Equilibrium equations and strain compatibility equations are applied in the verification. Also, a comparison with a newly-developed numerical method for dislocations near a free surface is performed as well. The developed solution is a function of the loop depth beneath the surface and can be used as a fundamental solution to solve elasticity, plasticity or dislocation problems.展开更多
奥氏体不锈钢是超临界水冷堆的堆内构件的候选材料之一,本文实验以奥氏体不锈钢AL-6XN为对象,研究了氢离子辐照对奥氏体钢微观结构的影响.在290℃和380℃下用100keV的H+2辐照,辐照剂量分别为0.5dpa和1.0dpa(displacement per atom).在29...奥氏体不锈钢是超临界水冷堆的堆内构件的候选材料之一,本文实验以奥氏体不锈钢AL-6XN为对象,研究了氢离子辐照对奥氏体钢微观结构的影响.在290℃和380℃下用100keV的H+2辐照,辐照剂量分别为0.5dpa和1.0dpa(displacement per atom).在290℃下,随辐照剂量增加,位错环平均直径从3.8nm增加到5.6nm,数密度略有下降.在380℃下辐照,产生了大尺寸位错环,随着剂量增加,位错环平均直径和数密度显著增加.实验结果表明,氢离子辐照AL-6XN不锈钢产生的缺陷主要是位错环,随辐照剂量增加,产生的位错环尺寸增大,提高辐照温度有利于位错环的迁移和聚集长大.展开更多
The effects of ion doses on the properties of boron implanted Si for n-type solar cell application were investigated with doses ranging from 5×10^14cm^-2 to 2×10^15cm^-2 and a subsequent two-step annealing p...The effects of ion doses on the properties of boron implanted Si for n-type solar cell application were investigated with doses ranging from 5×10^14cm^-2 to 2×10^15cm^-2 and a subsequent two-step annealing process in a tube furnace.With the help of the TCAD process simulation tool, knowledge on diffusion kinetics of dopants and damage evolution was obtained by fitting SIMS measured boron profiles. Due to insufficient elimination of the residual damage, the implanted emitter was found to have a higher saturation current density（J0e） and a poorer crystallographic quality. Consistent with this observation, V oc, J sc, and the efficiency of the all-implanted p^＋–n–n^＋solar cells followed a decreasing trend with an increase of the implantation dose. The obtained maximum efficiency was 19.59% at a low dose of 5×10^14cm^-2. The main efficiency loss under high doses came not only from increased recombination of carriers in the space charge region revealed by double-diode parameters of dark I–V curves, but also from the degraded minority carrier diffusion length in the emitter and base evidenced by IQE data. These experimental results indicated that clusters and dislocation loops had appeared at high implantation doses, which acted as effective recombination centers for photogenerated carriers.展开更多
基金Project supported by the National Center for Research and Development on Superconductivity
文摘Ⅰ. INTRODUCTION Critical current density J_c varies with structural imperfections in non-ideal type-Ⅱ superconductors, and it is sensitive to the defect concentration. Neutron irradiation has been established as a useful tool to increase the defect concentration in superconducting materials. Many experiments have shown that neutron irradiation at a suitable fluence would
基金financial supports from the International Science and Technology Cooperation Program of China (No. 2015DFR60370)the National Natural Science Foundation of China (Nos. 11275140 and U1532134)
文摘AL-6XN stainless steels, one of the candidate structure materials for supercritical water-cooled reactor, were irradiated from 0.5 to 5 dpa using 100 keV H2＋ ions at 290 and 380 ℃. Microstructures were characterized by transmission electron microscopy （TEM）. Dislocation loops were the dominant radiation-induced defects. All the dislocation loops had 1/3 〈111〉 type Burgers vector. Number density and size of the loops have been measured. Nucleation and evolution of dislocation loops were also investigated. Voids were observed only in the condition of 5 dpa at 380 ℃. Different evolution mechanisms of the radiation-induced dislocation loops were discussed. Effects of hydrogen and elevated temperature on the microstructural evolution were also investigated. Besides, the formed voids have a further effect on the evolution of dislocation loops.
文摘The strain and stress fields of a rectangular dislocation loop in an isotropic solid that is a semi-infinite medium (half medium) are developed here for a Volterra-type dislocation. Specifically, the loop is parallel to the free surface of the solid. The elastic fields of the dislocation loop are developed by integrating the displacement equation of infinitesimals dislocation loops over a finite rectangular loop area below the free surface. The strains and stress then follow from the small strain tensor and Hooke’s law for isotropic materials, respectively. In this paper, analytical verification and numerical verification for the elastic fields are both demonstrated. Equilibrium equations and strain compatibility equations are applied in the verification. Also, a comparison with a newly-developed numerical method for dislocations near a free surface is performed as well. The developed solution is a function of the loop depth beneath the surface and can be used as a fundamental solution to solve elasticity, plasticity or dislocation problems.
文摘奥氏体不锈钢是超临界水冷堆的堆内构件的候选材料之一,本文实验以奥氏体不锈钢AL-6XN为对象,研究了氢离子辐照对奥氏体钢微观结构的影响.在290℃和380℃下用100keV的H+2辐照,辐照剂量分别为0.5dpa和1.0dpa(displacement per atom).在290℃下,随辐照剂量增加,位错环平均直径从3.8nm增加到5.6nm,数密度略有下降.在380℃下辐照,产生了大尺寸位错环,随着剂量增加,位错环平均直径和数密度显著增加.实验结果表明,氢离子辐照AL-6XN不锈钢产生的缺陷主要是位错环,随辐照剂量增加,产生的位错环尺寸增大,提高辐照温度有利于位错环的迁移和聚集长大.
基金supported by the National Natural Science Foundation of China(Grant Nos.61275040,60976046,and 61021003)the National Basic Research Program of China(Grant No.2012CB934200)
文摘The effects of ion doses on the properties of boron implanted Si for n-type solar cell application were investigated with doses ranging from 5×10^14cm^-2 to 2×10^15cm^-2 and a subsequent two-step annealing process in a tube furnace.With the help of the TCAD process simulation tool, knowledge on diffusion kinetics of dopants and damage evolution was obtained by fitting SIMS measured boron profiles. Due to insufficient elimination of the residual damage, the implanted emitter was found to have a higher saturation current density（J0e） and a poorer crystallographic quality. Consistent with this observation, V oc, J sc, and the efficiency of the all-implanted p^＋–n–n^＋solar cells followed a decreasing trend with an increase of the implantation dose. The obtained maximum efficiency was 19.59% at a low dose of 5×10^14cm^-2. The main efficiency loss under high doses came not only from increased recombination of carriers in the space charge region revealed by double-diode parameters of dark I–V curves, but also from the degraded minority carrier diffusion length in the emitter and base evidenced by IQE data. These experimental results indicated that clusters and dislocation loops had appeared at high implantation doses, which acted as effective recombination centers for photogenerated carriers.
