Atomic-scale understanding of structural relaxation in simple and complex borosilicate glasses

2007 ◽  
Vol 75 (9) ◽  
Author(s):  
S. Sen ◽  
T. Topping ◽  
P. Yu ◽  
R. E. Youngman
Keyword(s):  
Structural Relaxation ◽  
Atomic Scale ◽  
Borosilicate Glasses

Atomic‐Scale Mechanisms of Densification in Cold‐Compressed Borosilicate Glasses

2021 ◽  
Author(s):  
Kuo‐Hao Lee ◽  
Yongjian Yang ◽  
Linfeng Ding ◽  
Benedikt Ziebarth ◽  
Mark J. Davis ◽  
...  
Keyword(s):  
Atomic Scale ◽  
Borosilicate Glasses

scholarly journals Atomic-scale mechanism of internal structural relaxation screening at polar interfaces

2018 ◽  
Vol 97 (18) ◽  
Author(s):  
Mingqiang Li ◽  
Xiaoxing Cheng ◽  
Ning Li ◽  
Heng-Jui Liu ◽  
Yen-Lin Huang ◽  
...  
Keyword(s):  
Structural Relaxation ◽  
Atomic Scale

Effects of chemical composition on the structural relaxation in ternary Zr-Cu-Al bulk glassy alloys studied by EXAFS and positron annihilation techniques.

2011 ◽  
Vol 1300 ◽  
Author(s):  
A Ishii ◽  
S Mineno ◽  
A Iwase ◽  
Y Yokoyama ◽  
T J. Konno ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Positron Annihilation ◽  
Free Volume ◽  
Structural Relaxation ◽  
Alloy System ◽  
Atomic Scale ◽  
Hypoeutectic Alloy ◽  
Positron Annihilation Lifetime ◽  
Glassy Alloys ◽  
Composition Ratios

ABSTRACTMechanical properties and thermal stability of bulk glassy alloys depend on their chemical composition ratios, although their detailed local structures especially around free volume have not been clarified yet. In order to know the origin of property dependence on alloy composition in Zr-Cu-Al ternary bulk glassy alloys in a view point of atomic scale, positron annihilation lifetime, coincidence Doppler broadening (CDB) and EXAFS (extended X-ray absorption fine structure) measurements have been employed for eutectic Zr50Cu40Al10 and hypoeutectic Zr60Cu30Al10 bulk glassy alloys before and after structural relaxation by annealing below glass transition temperature Tg.The result of CDB experiment, which represents the electron momentum distribution around free volume, shows that significant atomic reordering around free volume does not take place by the annealing in each alloy. Besides, CDB ratio profiles for each alloy suggest that the fraction of Zr atom around free volume does not match the chemical composition of each alloy system. Change in positron lifetime, which is proportional to the size of free volume, during annealing for hypoeutectic alloy almost remains unchanged.

Structural relaxation mechanisms in hydrous sodium borosilicate glasses

2018 ◽  
Vol 497 ◽  
pp. 30-39 ◽  
Author(s):  
H. Behrens ◽  
U. Bauer ◽  
S. Reinsch ◽  
P. Kiefer ◽  
R. Müller ◽  
...  
Keyword(s):  
Structural Relaxation ◽  
Borosilicate Glasses

Structure and migration of planar defects in crystals observed in atomic scale

1978 ◽  
Vol 36 (1) ◽  
pp. 284-285 ◽  
Author(s):  
H. Hashimoto ◽  
Y. Sugimoto ◽  
Y. Takai ◽  
H. Endoh
Keyword(s):  
Electron Microscope ◽  
Rotation Angle ◽  
Crystal Surface ◽  
Electron Gun ◽  
Atomic Scale ◽  
Present Observation ◽  
Twist Boundary ◽  
Optical Magnification ◽  
Zinc Crystal ◽  
And Migration

As was demonstrated by the present authors that atomic structure of simple crystal can be photographed by the conventional 100 kV electron microscope adjusted at “aberration free focus (AFF)” condition. In order to operate the microscope at AFF condition effectively, highly stabilized electron beams with small energy spread and small beam divergence are necessary. In the present observation, a 120 kV electron microscope with LaB6 electron gun was used. The most of the images were taken with the direct electron optical magnification of 1.3 million times and then magnified photographically.1. Twist boundary of ZnSFig. 1 is the image of wurtzite single crystal with twist boundary grown on the surface of zinc crystal by the reaction of sulphur vapour of 1540 Torr at 500°C. Crystal surface is parallel to (00.1) plane and electron beam is incident along the axis normal to the crystal surface. In the twist boundary there is a dislocation net work between two perfect crystals with a certain rotation angle.

Resolution in the scanning tunneling microscope

1991 ◽  
Vol 49 ◽  
pp. 488-489
Author(s):  
R. J. Wilson ◽  
D. D. Chambliss ◽  
S. Chiang ◽  
V. M. Hallmark
Keyword(s):  
Scanning Tunneling Microscope ◽  
Fundamental Principle ◽  
Atomic Scale ◽  
Lateral Resolution ◽  
Scanning Tunneling ◽  
Electronic Noise ◽  
Vertical Resolution ◽  
Tunneling Microscopy ◽  
Spatial Profile ◽  
Theoretical Analyses

Scanning tunneling microscopy (STM) has been used for many atomic scale observations of metal and semiconductor surfaces. The fundamental principle of the microscope involves the tunneling of evanescent electrons through a 10Å gap between a sharp tip and a reasonably conductive sample at energies in the eV range. Lateral and vertical resolution are used to define the minimum detectable width and height of observed features. Theoretical analyses first discussed lateral resolution in idealized cases, and recent work includes more general considerations. In all cases it is concluded that lateral resolution in STM depends upon the spatial profile of electronic states of both the sample and tip at energies near the Fermi level. Vertical resolution is typically limited by mechanical and electronic noise.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

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