Electron-Hole Excitation Induced Softening in Boron Carbide Based Superhard Materials

2021 ◽  
Author(s):  
Yi He ◽  
Yidi Shen ◽  
Bin Tang ◽  
Qi An
Keyword(s):  
Boron Carbide ◽  
Superhard Materials ◽  
Electron Hole ◽  
Hole Excitation

scholarly journals Dislocation-mediated shear amorphization in boron carbide

2021 ◽  
Vol 7 (8) ◽  
pp. eabc6714 ◽  
Author(s):  
Kolan Madhav Reddy ◽  
Dezhou Guo ◽  
Shuangxi Song ◽  
Chun Cheng ◽  
Jiuhui Han ◽  
...  
Keyword(s):  
Boron Carbide ◽  
Structural Transition ◽  
Activation Volume ◽  
Structural Evolution ◽  
Dislocation Nucleation ◽  
Superhard Materials ◽  
Rate Dependent ◽  
Transmission Electron ◽  
Lower Activation ◽  
Underlying Mechanisms

The failure of superhard materials is often associated with stress-induced amorphization. However, the underlying mechanisms of the structural evolution remain largely unknown. Here, we report the experimental measurements of the onset of shear amorphization in single-crystal boron carbide by nanoindentation and transmission electron microscopy. We verified that rate-dependent loading discontinuity, i.e., pop-in, in nanoindentation load-displacement curves results from the formation of nanosized amorphous bands via shear amorphization. Stochastic analysis of the pop-in events reveals an exceptionally small activation volume, slow nucleation rate, and lower activation energy of the shear amorphization, suggesting that the high-pressure structural transition is activated and initiated by dislocation nucleation. This dislocation-mediated amorphization has important implications in understanding the failure mechanisms of superhard materials at stresses far below their theoretical strengths.

Blueshift of the TO Phonon Resonance in GaAs by Femtosecond Electron-Hole Excitation

2020 ◽  
Author(s):  
K. Reimann ◽  
A. Ghalgaoui ◽  
M. Woerner ◽  
T. Elsaesser ◽  
C. Flytzanis ◽  
...  
Keyword(s):  
Electron Hole ◽  
Hole Excitation

scholarly journals Bipolaron formed through electron-hole excitation

2020 ◽  
Vol 96 (2) ◽  
pp. 025801
Author(s):  
Chen-Huan Wu
Keyword(s):  
Electron Hole ◽  
Hole Excitation

Composite superhard materials containing boron carbide

2007 ◽  
Vol 29 (6) ◽  
pp. 340-343 ◽  
Author(s):  
A. A. Shul’zhenko ◽  
D. A. Stratiichuk ◽  
M. G. Loshak ◽  
L. I. Aleksandrova ◽  
G. S. Oleinik ◽  
...  
Keyword(s):  
Boron Carbide ◽  
Superhard Materials

Frequency Upshift of the Transverse Optical Phonon Resonance in GaAs by Femtosecond Electron-Hole Excitation

2020 ◽  
Vol 125 (2) ◽  
Author(s):  
Ahmed Ghalgaoui ◽  
Klaus Reimann ◽  
Michael Woerner ◽  
Thomas Elsaesser ◽  
Christos Flytzanis ◽  
...  
Keyword(s):  
Optical Phonon ◽  
Transverse Optical ◽  
Electron Hole ◽  
Hole Excitation

Phonon-Induced Electron–Hole Excitation and ac Conductance in Molecular Junction

2016 ◽  
Vol 85 (4) ◽  
pp. 043703 ◽  
Author(s):  
Akiko Ueda ◽  
Yasuhiro Utsumi ◽  
Hiroshi Imamura ◽  
Yasuhiro Tokura
Keyword(s):  
Molecular Junction ◽  
Electron Hole ◽  
Hole Excitation ◽  
Ac Conductance

Current Status of Solid-State X-Ray Systems

1985 ◽  
Vol 43 ◽  
pp. 158-161
Author(s):  
Martin Peckerar ◽  
Anastasios Tousimis
Keyword(s):  
Solid State ◽  
Electric Fields ◽  
Spectral Lines ◽  
Current Status ◽  
Mobile Charge ◽  
Electron Hole ◽  
X Ray ◽  
Sensing Systems ◽  
Transmission Electron ◽  
Electron Microscopes

Solid state x-ray sensing systems have been used for many years in conjunction with scanning and transmission electron microscopes. Such systems conveniently provide users with elemental area maps and quantitative chemical analyses of samples. Improvements on these tools are currently sought in the following areas: sensitivity at longer and shorter x-ray wavelengths and minimization of noise-broadening of spectral lines. In this paper, we review basic limitations and recent advances in each of these areas. Throughout the review, we emphasize the systems nature of the problem. That is. limitations exist not only in the sensor elements but also in the preamplifier/amplifier chain and in the interfaces between these components.Solid state x-ray sensors usually function by way of incident photons creating electron-hole pairs in semiconductor material. This radiation-produced mobile charge is swept into external circuitry by electric fields in the semiconductor bulk.

A correlation of CL emissions from Penrith sandstone with elemental distributions obtained by simultaneous SEM-CL and EDS analysis

1995 ◽  
Vol 53 ◽  
pp. 392-393
Author(s):  
Paul J. Wright
Keyword(s):  
Optical Microscope ◽  
Electron Gun ◽  
High Electron ◽  
Collection System ◽  
Electron Hole ◽  
Depositional Processes ◽  
Eds Analysis ◽  
Distribution Mapping ◽  
Backscattered Electron ◽  
Electron Imaging

Most industrial and academic geologists are familiar with the beautiful red and orange cathodoluminescence colours produced by carbonate minerals in an optical microscope with a cold cathode electron gun attached. The cement stratigraphies interpreted from colour photographs have been widely used to determine the post depositional processes which have modified sedimentary rock textures.However to study quartzose materials high electron densities and kV's are necessary to stimulate sufficient emission. A scanning electron microscope with an optical collection system and monochromator provides an adequate tool and gives the advantage of providing secondary and backscattered electron imaging as well as elemental analysis and distribution mapping via standard EDS/WDS facilities.It has been known that the incorporation of many elements modify the characteristics of the CL emissions from geological materials. They do this by taking up positions between the valence and conduction band thus providing sites to assist in the recombination of electron hole pairs.

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