scholarly journals Transmission Electron Microscopy Study of Cascade Collapse in Copper During in- Situ Ion- Irradiation at Elevated Temperatures

1997 ◽  
Vol 504 ◽  
Author(s):  
T. L. Daulton ◽  
M. A. Kirk ◽  
L. E. Rehn

ABSTRACTThe basic mechanisms driving the collapse of point defects produced in collision cascades are investigated by transmission electron microscope (TEM) characterization of defect microstructures produced in fcc-Cu irradiated with low-fluences of heavy (100 keV Kr) ions at elevated temperature (23–600°C). Areal defect yields are determined from direct TEM observation of the total defect production integrated over the duration of the in-situ ion-irradiation. They are unequivocally demonstrated to decrease with increasing lattice temperature. This decrease in defect yield indicates a proportional decrease in the probability of collapse of cascade regions into defects of size where visible contrast is produced in a TEM.

2008 ◽  
Vol 14 (S2) ◽  
pp. 1020-1021
Author(s):  
YJ Park ◽  
SH Han ◽  
HN Kim

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008


2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Dnyaneshwar S. Gavhane ◽  
Heleen van Gog ◽  
Balu Thombare ◽  
Gaurav Lole ◽  
L. Christiaan Post ◽  
...  

AbstractThermally induced structural transformation of 2D materials opens unique avenues for generating other 2D materials by physical methods. Imaging these transitions in real time provides insight into synthesis routes and property tuning. We have used in situ transmission electron microscopy (TEM) to follow thermally induced structural transformations in layered CoSe2. Three transformation processes are observed: orthorhombic to cubic-CoSe2, cubic-CoSe2 to hexagonal-CoSe, and hexagonal to tetragonal-CoSe. In particular, the unit-cell-thick orthorhombic structure of CoSe2 transforms into cubic-CoSe2 via rearrangement of lattice atoms. Cubic-CoSe2 transforms to hexagonal-CoSe at elevated temperatures through the removal of chalcogen atoms. All nanosheets transform to basal-plane-oriented hexagonal 2D CoSe. Finally, the hexagonal to tetragonal transformation in CoSe is a rapid process wherein the layered morphology of hexagonal-CoSe is broken and islands of tetragonal-CoSe are formed. Our results provide nanoscopic insights into the transformation processes of 2D CoSe2 which can be used to generate these intriguing 2D materials and to tune their properties by modifying their structures for electro-catalytic and electronic applications.


2005 ◽  
Vol 20 (7) ◽  
pp. 1837-1843 ◽  
Author(s):  
R. Anton

In a specially equipped transmission electron microscope (TEM), Ni particles were vapor deposited onto thin films of amorphous carbon (a-C), and subsequent reactions with the carbon support were observed at elevated temperatures. Particles deposited at temperatures around 370 °C developed a graphite shell at above 600 °C and subsequently spread and graphitized the substrate. This activity was enhanced by hydrogen. The speed of graphitization significantly increased during spreading of the metal, which is attributed to the concomitant increase of the length of the reaction front, as well as to a purifying effect of hydrogen. It is concluded that the driving force for spreading of the Ni is the interdiffusion and catalytic conversion of carbonto graphite at the reaction front. Particles deposited at 500 °C remained inactive at670 °C. This is probably due to the formation of a rather stable carbidic or graphitic interlayer during deposition.


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