Secondary electron imaging of YBa2Cu3O7-x high-Tc superconductors in Scanning Transmission Electron Microscope

1989 ◽  
Vol 47 ◽  
pp. 684-685
Author(s):  
D. R. Liu ◽  
D. B. Williams
Keyword(s):  
Electron Microscope ◽  
Secondary Electron ◽  
Scanning Transmission Electron Microscope ◽  
Superconducting Phase ◽  
Contrast Imaging ◽  
High Tc ◽  
Bright Contrast ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Imaging

The secondary electron imaging technique in a scanning electron microscope (SEM) has been used first by Millman et al. in 1987 to distinguish between the superconducting phase and the non-superconducting phase of the YBa2Cu3O7-x superconductors. They observed that, if the sample was cooled down below the transition temperature Tc and imaged with secondary electrons, some regions in the image would show dark contrast whereas others show bright contrast. In general, the contrast variation of a SEM image is the variation of the secondary electron yield over a specimen, which in turn results from the change of topography and conductivity over the specimen. Nevertheless, Millman et al. were able to demonstrate with their experimental results that the dominant contrast mechanism should be the conductivity variation and that the regions of dark contrast were the superconducting phase whereas the regions of bright contrast were the non-superconducting phase, because the latter was a poor conductor and consequently, the charge building-up resulted in high secondary electron emission. This observation has since aroused much interest amoung the people in electron microscopy and high Tc superconductivity. The present paper is the preliminary report of our attempt to carry out the secondary electron imaging of this material in a scanning transmission electron microscope (STEM) rather than in a SEM. The advantage of performing secondary electron imaging in a TEM is obvious that, in a TEM, the spatial resolution is higher and many more complementary techniques, e.g, diffraction contrast imaging, phase contrast imaging, electron diffraction and various microanalysis techniques, are available.

Fabrication of a Boersch phase plate for phase contrast imaging in a transmission electron microscope

2006 ◽  
Vol 77 (3) ◽  
pp. 033701 ◽  
Author(s):  
K. Schultheiß ◽  
F. Pérez-Willard ◽  
B. Barton ◽  
D. Gerthsen ◽  
R. R. Schröder
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Phase Contrast ◽  
Phase Contrast Imaging ◽  
Phase Plate ◽  
Contrast Imaging ◽  
Transmission Electron

scholarly journals Resolving hydrogen atoms at metal-metal hydride interfaces

2020 ◽  
Vol 6 (5) ◽  
pp. eaay4312 ◽  
Author(s):  
Sytze de Graaf ◽  
Jamo Momand ◽  
Christoph Mitterbauer ◽  
Sorin Lazar ◽  
Bart J. Kooi
Keyword(s):  
Metal Hydride ◽  
Phase Contrast ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Hydrogen Atoms ◽  
Volumetric Density ◽  
Transmission Electron ◽  
Metal Metal ◽  
Scanning Transmission ◽  
Differential Phase Contrast

Hydrogen as a fuel can be stored safely with high volumetric density in metals. It can, however, also be detrimental to metals, causing embrittlement. Understanding fundamental behavior of hydrogen at the atomic scale is key to improve the properties of metal-metal hydride systems. However, currently, there is no robust technique capable of visualizing hydrogen atoms. Here, we demonstrate that hydrogen atoms can be imaged unprecedentedly with integrated differential phase contrast, a recently developed technique performed in a scanning transmission electron microscope. Images of the titanium-titanium monohydride interface reveal stability of the hydride phase, originating from the interplay between compressive stress and interfacial coherence. We also uncovered, 30 years after three models were proposed, which one describes the position of hydrogen atoms with respect to the interface. Our work enables previously unidentified research on hydrides and is extendable to all materials containing light and heavy elements, including oxides, nitrides, carbides, and borides.

Sign in / Sign up

Export Citation Format

Share Document