Chuangxin Ma

Effects of the crystal structure on electrical and optical properties of pyrite FeS2 films prepared by thermally sulfurizing iron films

Based on experimental results and theoretical analysis effects of the crystal structure on the optical and electrical properties of pyrite FeS2 films produced by thermally sulfurizing iron films at various temperatures have been systematically studied. The results indicate that the crystal structure and some related factors, such as the crystallization and the stoichiometry, remarkably influence the optical and electrical performances of the pyrite films. It is also shown that the preferred orientation of the crystal grain plays a major role in determining the crystal structure and the optical and electrical properties of the pyrite FeS2 films. Also we find that it is the crystal grains, rather than the particles that exercise a decisive influence on the electrical performance of pyrite films

Positron beam studies of argon-irradiated polycrystal α-Zr

Doppler broadening spectroscopy was performed using a variable-energy positron beam to investigate the effect of defects induced by 150-keV Ar-ion-irradiated α-Zr bulk material. S parameter in the damaged layer of the as-irradiated sample induced by ion irradiation increased with the increasing implantation dose. Isochronal annealing between 350 and 800°C in vacuum studies was carried out to investigate the thermal stability of defects in the oxide surface and damaged layer for low-dose (1×1014cm2) and high-dose (1×1016cm2) irradiated samples. The results of S-W plot measured at different annealing temperatures showed that the positron-trapping center had changed. The Ar-decorated voids or vacancies, which formed in high-dose implantation samples by Ar ions combining with open-volume defects, are stable and do not recover until at high annealing temperatures. Comparing the annealing behavior of the high-dose and low-dose implantation samples show that the recovery process of open-volume defects such as va...

Depth discrimination method based on a multirow linear array detector for push-broom Compton scatter imaging

A depth discrimination method is devised based on a multirow linear array detector for push-broom Compton scatter imaging. Two or more rows of detector modules are placed at different positions towards a sample. An improved parallel-hole collimator is fixed in front of the modules to restrict their fields of view. The depth information could be indicated by comparing the signal differences. In addition, an available detector and several related simulations using GEANT4 are given to support the method well.