ZHU Zhiyong SUN Youmei JIN Yunfan LI Changlin HOU Mingdong LIU Changlong ZHANG Chonghong MENG Qinghua WANG Zhiguang CHEN Keqin. Positron lifetime study of SiO2 glass irradiated with high energy Ar ions[J]. Nuclear techniques, 2001, (6): 439-444.
ZHU Zhiyong SUN Youmei JIN Yunfan LI Changlin HOU Mingdong LIU Changlong ZHANG Chonghong MENG Qinghua WANG Zhiguang CHEN Keqin. Positron lifetime study of SiO2 glass irradiated with high energy Ar ions[J]. Nuclear techniques, 2001, (6): 439-444.DOI:
SiO 2 glass specimens were irradiated with 1.15GeV Ar ions at room temperature. Positron lifetime spectroscopy was applied to investigate the radiation induced microscopic changes. It was found that for the unirradiated specimen about 81% positrons annihilate from positronium (Ps) states. Free volumes of about 2.5nm in radius and distributed from 0.02—0.13nm 3 are found from the o-Ps lifetime. Under irradiation the free volume distribution function narrows down and the peak position shifts to lower value
which indicate the densification of the material. With increasing dose
the intensity of the second lifetime component increases whereas the intensity of the component corresponding to o-Ps decreases. This was attributed to the prefered annihilation of positrons with the radiation-ionized electrons wandering in free volumes.