Defect Microstructure in Copper after Low Fluence Irradiation with 440-Mev Argon and 230-Mev Neon Ions

A saturation of the yield strength appears in the post irradiation hardening of copper irradiated with high energy heavy ions, in the range from 10(-3)-10(-2) dpa. The saturation value of the yield strength is significantly lower than that measured after irradiation with 14 MeV neutrons to comparable doses. To investigate the origin of this difference in behaviour, a detailed transmission electron microscope study of the post-irradiation defect cluster microstructure was undertaken. In specimens irradiated with 440 MeV Ar and 230 MeV ions up to 0.01 dpa the microstructure is composed by large dislocation loops (up to 25 nm), stacking fault tetrahedra (3 nm) and small defect clusters (< 2 nm). In the case of the Ar irradiation, the total defect density is 2.8 x 10(23) m(-3) at 10(-2) dpa. Of these, 40-50% are stacking fault tetrahedra, whereas only 1-5% are large loops. The total defect cluster concentration shows a (dose)(0.5) behaviour, with no saturation up to highest dose observed (10(-2) dpa)

In situ and LCSM study of mechanical stress in ruby induced by swift heavy ions

Accumulation of mechanical stress in Аl2O3:Сг crystals induced by high energy heavy ions has been studied by using in situ ionoluminescence and postradiation laser confocal scanning microscopy measurements. It was found that lattice defects created via high level electronic excitation lead to generation of high level compressive stresses even at moderate ion fluences, less than 1*10^12 cm^-2. The results obtained are discussed in the frame of model suggesting interaction of non overlapping highly stressed track regions with individual "Cr3+ piezosensors"

New method based on atomic force microscopy for in-depth characterization of damage in Si irradiated with 209 MeV Kr

Si was irradiated with 209 MeV Kr ions on an (010) oriented surface. Then atomic force microscopy (AFM) was used to measure the roughness on the adjacent (100) plane (the original wafer surface). The distance on this later plane is called "depth" as measured from the (010)/(100) edge. Good agreement is found in projected range values between AFM, spreading resistance (SR) data, and Monte Carlo (TRIM) simulation. Four distinct damage zones are found: zone A, dominated by electronic stopping effects; zone B, electronically assisted elastic collisions; zone C, dominant nuclear stopping; and zone D, defects created by the channeled fraction of the beam

Dominantly epitaxial growth of graphene on Ni (1 1 1) substrate

Graphene was grown on a Ni (1 1 1) thin layer, used as a substrate. The Ni layer itself was grown on singlecrystal sapphire (0 0 0 1). Carbon was deposited by chemical vapor deposition using a mixture of methane,argon and hydrogen at atmospheric pressure implementing a constant gas flow (4.8–5 l/min) varying boththe gas composition and the deposition temperature (900–980◦C) and cooling rate (8–16◦C/min) in thedifferent experiments. Formation of uninterruptedly grown epitaxial single layer graphene was observedover the Ni (1 1 1) thin film substrate. Epitaxial growth was proven through STM measurements. Electrondiffraction studies, also confirmed by STM, demonstrated that only one dominant orientation exists inthe graphene, both results providing evidence of the epitaxial growth. On top of the, continuous, largearea graphene flakes were also observed with sizes varying between 10 nm and 10 m. Most of the topflakes are turbostratically related to the continuous underlying epitaxial graphene layer. The formation ofthe graphene layer with constant dominant orientation was observed over millimeter wide areas. Largeareas (≈20–40 m in diameter) of continuous, epitaxial graphene, free of additional deposits and flakeswere obtained for the best set of growth parameters.16101sciescopu

In situ and LCSM study of mechanical stress in ruby induced by swift heavy ions

Accumulation of mechanical stress in Аl2O3:Сг crystals induced by high energy heavy ions has been studied by using in situ ionoluminescence and postradiation laser confocal scanning microscopy measurements. It was found that lattice defects created via high level electronic excitation lead to generation of high level compressive stresses even at moderate ion fluences, less than 1*10^12 cm^-2. The results obtained are discussed in the frame of model suggesting interaction of non overlapping highly stressed track regions with individual "Cr3+ piezosensors"