Sun You-Mei

1 GeV Ar ions induced amorphization in garnet

Abstract Amorphization phenomenon of yttrium iron garnet (YIG) Y 3 Fe 5 O 12 induced by 1 GeV Ar ions irradiation at the temperature 195 K has been investigated by means of the sample-tilting X-ray diffraction (STD), optical absorption spectroscopy, Mossbauer spectroscopy and saturation magnetization measurement. The analysis results indicate that there exist a critical dose 1.0 × 10 14 ions/cm 2 and a threshold value of electronic energy loss S e = 2.9MeV/μm. Above both values the lattice constant a , the optical absorption coefficient α, and the fraction of the paramagnetic phase F p increase with the increase of electronic energy loss, but saturation magnetization decreases. For the first time, the nearly complete amorphous state was observed at S e = 8.3MeV μm with irradiation doses equal or more than 1.0 × 10 14 ions/cm 2 . It is found that the transformation from crystalline to amorphous state is a gradual process in which the electronic stopping power plays a main role and a certain dose is needed.

Preparation of Silver Nanowires in Ion-track Membranes

Polycarbonate (PC) membranes were irradiated with swift heavy ions and latent tracks were created along the ions′trajectories. Nanopores, diameters between 100 and 500 nm, were obtained after illuminating the membranes with UV light and etching in NaOH solution. Silver nanowires were produced in the etched ion-track membranes by electrochemical deposition. The morphology and crystallinity of the silver nanowires were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Under certain conditions (deposition voltage 25 mV, current density 1-2 mA·cm~(-2), temperature 50 ℃, electrolyte 0.1 mol·L~(-1) AgNO_3), single-crystalline silver nanowires with preferred orientation along the [111] direction can be synthesized.

IRRADIATION EQUIPMENT OF HIRFL

Abstract An irradiation equipment has been set up at the Heavy Ion Research Facility in Lanzhou (HIRFL). The irradiation equipment creates favourable conditions for developing non-nuclear science in China.

Surface morphology of GaN bombarded by highly charged 126 Xe q + ions

N-type GaN films bombarded with different highly charged 126Xeq+-ions（9≤q≤30） at room temperature was studied by atomic force microscopy. The experimental results show that when q exceeds the threshold value 18, remarkable swelling turns into obvious erosion in the irradiated area. On the other hand, surface disorder of GaN films strongly depends on the charge state q of ions, incident angle and ion influence, and the damage behavior of films is unrelated to the kinetic energy within the scope of experimental parameters（180 keV≤Ek≤600 keV）.For q=18, the surface morphology of the films almost does hot change at normal incidence, and at incidence angle of 30° relative to the film surface, there appears small-scale swelling in irradiated region and a low step forms between the irradiated and un-irradiated regions. For q 18, film surface is etched, forming a deep dump with a high step with the increase of ions influence. Unambiguous indentations relevant to the ion influence on the step appear. Furthermore, the step height is proportional to the ion influence approximately and is much higher for tilted incidence than normal incidence.