电镀纳米镍缺陷的正电子研究

Defect study of electrodeposited nanocrystalline Ni by positronannihilation technique

用正电子寿命谱研究了电镀纳米镍（～２０ｍｍ）中的微观缺陷，分析了缺陷中的氢对正电子寿命的影响。实验结果表明：界面存在单空位大小的自由体积、６－１０个空位大小的自由体积和微孔洞三类缺陷；纳米镍在５００℃真空退火２ｈ后，中间寿命和最长寿命的强度不受影响，表明中间寿命和最长寿命所对应的缺陷具有很好的热稳定性。

Defects in electrodeposited nanocrystalline Ni and the effect of hydrogen on the positron lifetime have been studied by the positron annihilation technique. There exist three kinds of defects at the interface, i. e. the free volumes with a monovacancy, a cluster of 6-10 vacancies and a micro-void, respectively. It is found that the moderate and longest lifetimes will not be affected when the nano-Ni is annealed at 500℃ in vacuum for 2h, which suggests that the defects related to these lifetimes show surprisingly great thermal stability.