Elucidating “screw dislocation”-driven film formation of sodium thiosulphate with complex hierarchical molecular assembly

2017 ◽  
Vol 204 ◽  
pp. 251-269 ◽  
Author(s):  
Deepak Dwivedi ◽  
Katerina Lepkova ◽  
Thomas Becker ◽  
Matthew R. Rowles
Keyword(s):  
Screw Dislocation ◽  
Materials Science ◽  
Chemical Elements ◽  
Film Formation ◽  
Hierarchical Structures ◽  
Molecular Assembly ◽  
Surface Films ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Sodium Thiosulphate

Sodium thiosulphate (Na2S2O3) films were synthesized on carbon steel substrates through solution deposition, and a film formation growth mechanism is delineated in detail herein. Dislocation-driven film formation took place at the lower concentration of Na2S2O3 (0.1 M) studied, where screw dislocation loops were identified. Interestingly, we observed the co-existence of screw dislocation spiral loops and hierarchically-ordered molecular assembly in the film, and showed the importance of hierarchical morphology in the origin of screw dislocation. The screw dislocation loops were, however, distorted at the higher studied concentration of Na2S2O3 (0.5 M), and no hierarchical structures were formed. The mechanisms of film formation are discussed in detail and provide new insights into our understanding regarding morphology of the hierarchical molecular assembly, screw dislocation loop formation, and the role of chemical elements for their development. The main crystalline and amorphous phases in the surface films were identified as pyrite/mackinawite and magnetite. As sodium thiosulphate is widely used for energy, corrosion inhibition, nanoparticle synthesis and catalysis applications, the knowledge generated in this study is applicable to the fields of corrosion, materials science, materials chemistry and metallurgy.

Point Defect Absorption and Dislocation Loop Formation at Grain Boundaries in Hvem-Irradiated Zr and Its Alloys:1. Influence of Solute Addition

1985 ◽  
Vol 43 ◽  
pp. 350-351
Author(s):  
R.A. Herring ◽  
M. Griffiths ◽  
M.H Loretto ◽  
R.E. Smallman
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Point Defect ◽  
Reactor Core ◽  
Solute Concentration ◽  
Nuclear Industry ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Component Material ◽  
Impurity Interaction

Because Zr is used in the nuclear industry to sheath fuel and as structural component material within the reactor core, it is important to understand Zr's point defect properties. In the present work point defect-impurity interaction has been assessed by measuring the influence of grain boundaries on the width of the zone denuded of dislocation loops in a series of irradiated Zr alloys. Electropolished Zr and its alloys have been irradiated using an AEI EM7 HVEM at 1 MeV, ∼675 K and ∼10-6 torr vacuum pressure. During some HVEM irradiations it has been seen that there is a difference in the loop nucleation and growth behaviour adjacent to the grain boundary as compared with the mid-grain region. The width of the region influenced by the presence of the grain boundary should be a function of the irradiation temperature, dose rate, solute concentration and crystallographic orientation.

X-ray mapping without STEM

1994 ◽  
Vol 52 ◽  
pp. 508-509
Author(s):  
Judith M. Brock ◽  
Max T. Otten
Keyword(s):  
Life Science ◽  
Materials Science ◽  
Chemical Elements ◽  
Full Description ◽  
Scanning System ◽  
Elemental Distribution ◽  
X Ray ◽  
Transmission Electron ◽  
Distribution Of Elements ◽  
Made In

A knowledge of the distribution of chemical elements in a specimen is often highly useful. In materials science specimens features such as grain boundaries and precipitates generally force a certain order on mental distribution, so that a single profile away from the boundary or precipitate gives a full description of all relevant data. No such simplicity can be assumed in life science specimens, where elements can occur various combinations and in different concentrations in tissue. In the latter case a two-dimensional elemental-distribution image is required to describe the material adequately. X-ray mapping provides such of the distribution of elements.The big disadvantage of x-ray mapping hitherto has been one requirement: the transmission electron microscope must have the scanning function. In cases where the STEM functionality – to record scanning images using a variety of STEM detectors – is not used, but only x-ray mapping is intended, a significant investment must still be made in the scanning system: electronics that drive the beam, detectors for generating the scanning images, and monitors for displaying and recording the images.

The Chemical Bond Across the Periodic Table: Part 1 – First Row and Simple Metals

2020 ◽  
Author(s):  
Gabriel Freire Sanzovo Fernandes ◽  
Leonardo dos Anjos Cunha ◽  
Francisco Bolivar Correto Machado ◽  
Luiz Ferrão
Keyword(s):  
Physical Chemistry ◽  
Chemical Bond ◽  
Materials Science ◽  
Chemical Elements ◽  
Orbital Theory ◽  
Solid State Physics ◽  
Band Theory ◽  
Van Der Waals Clusters ◽  
Earth Systems ◽  
Chemical Content

<p>Chemical bond plays a central role in the description of the physicochemical properties of molecules and solids and it is essential to several fields in science and engineering, governing the material’s mechanical, electrical, catalytic and optoelectronic properties, among others. Due to this indisputable importance, a proper description of chemical bond is needed, commonly obtained through solving the Schrödinger equation of the system with either molecular orbital theory (molecules) or band theory (solids). However, connecting these seemingly different concepts is not a straightforward task for students and there is a gap in the available textbooks concerning this subject. This work presents a chemical content to be added in the physical chemistry undergraduate courses, in which the framework of molecular orbitals was used to qualitatively explain the standard state of the chemical elements and some properties of the resulting material, such as gas or crystalline solids. Here in Part 1, we were able to show the transition from Van der Waals clusters to metal in alkali and alkaline earth systems. In Part 2 and 3 of this three-part work, the present framework is applied to main group elements and transition metals. The original content discussed here can be adapted and incorporated in undergraduate and graduate physical chemistry and/or materials science textbooks and also serves as a conceptual guide to subsequent disciplines such as quantum chemistry, quantum mechanics and solid-state physics.</p>

Effect of Formation and Growth of Dislocation Loops and Cavities on Low-Temperature Swelling of Irradiated Uranium-Molybdenum Alloys

1998 ◽  
Vol 540 ◽  
Author(s):  
J. Rest ◽  
G. L. Hofman ◽  
I. I. Konovalov ◽  
A. A. Maslov
Keyword(s):  
Low Temperature ◽  
Rate Theory ◽  
Subgrain Structure ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Molybdenum Alloys ◽  
Fission Gas ◽  
Swelling Mechanism ◽  
Test Reactor ◽  
Low Irradiation

AbstractScanning electron photomicrographs of U–10 wt.% Mo irradiated at low temperature in the Advanced Test Reactor (ATR) to about 40 at.% burnup show the presence of cavities. We have used a rate-theory-based model to investigate the nucleation and growth of cavities during low-temperature irradiation of uranium-molybdenum alloys in the presence of irradiation-induced interstitial-loop formation and growth. Our calculations indicate that the swelling mechanism in the U–10 wt.% Mo alloy at low irradiation temperatures is fission-gas driven. The calculations also indicate that the observed bubbles must be associated with a subgrain structure. Calculated bubble-size-distributions are compared with irradiation data.

The Effect of a Thin Sample on the Extended Defect Evolution in Si+ Implanted Si

1997 ◽  
Vol 490 ◽  
Author(s):  
Jing-Hong Li ◽  
Kevin S. Jones
Keyword(s):  
Dislocation Loop ◽  
Ex Situ ◽  
Dissolution Process ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Thin Sample ◽  
Extended Defect ◽  
Defect Evolution ◽  
Annealing Study

ABSTRACTThe annealing kinetics of implant damage in Si+ implanted Si has been investigated using in-situ and ex-situ annealing of transmission electron microscopy (TEM) samples prepared prior to annealing. The defect evolution at 800°C was studied for a Si wafer implanted with Si+ at 100keV to a dose of 2×1014 cm-2. This implant was above the sub-threshold loop formation threshold allowing one to study simultaneously the {311} defect dissolution and dislocation loop nucleation and growth. In order to study the effect on the defect evolution of using a thin sample for an in-situ annealing experiment, a pair of samples, one thick and one thinned into a TEM sample, were annealed in a furnace simultaneously. It was found that the presence of a second surface 2000Å below the implant damage did not affect the extended defect evolution. For the in-situ annealing study it was found that the {311} dissolution process and sub-threshold dislocation loop formation process was not affected by the TEM electron beam at 160kV as long as an 800°C furnace pre-anneal was done prior to in-situ annealing. The dissolution rate of the {311} defects was used to confirm the TEM holder furnace temperature. The results of both the in-situ the {311} defects is released during the 311 dissolution process and 30% comes to reside in dislocation loops. Thus, the loops appear to contain a significant fraction of the total interstitial concentration introduced by the implant.

The detection of submicroscopic lattice defects in aluminium utilizing a vacancy supersaturation

1969 ◽  
Vol 314 (1516) ◽  
pp. 129-141 ◽  
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Lattice Defects ◽  
Supersaturated Solution ◽  
Dislocation Loops ◽  
Single Slip ◽  
Quench Temperature ◽  
Decoration Technique

The conditions under which submicroscopic defects can be revealed due to decoration by the precipitation of vacant lattice sites from a supersaturated solution have been investigated in aluminium. It is shown that quench temperature, specimen purity and other conditions have to be so chosen that the nucleation of self-sinks is minimized while an adequate vacancy supersaturation is maintained. The conditions for the optimum visibility of defects revealed in this way have been studied primarily by observing the variation in the density of rows of dislocation loops along <110> directions. This decoration technique has been used in quenched single crystals deformed in single slip to show that these rows and also narrow faulted dislocation dipoles with their long axes in the <110> direction form along the specific <110> direction predicted from a hypothesis involving the dragging of a jog by a moving screw dislocation.

scholarly journals The type identification of dislocation loops by TEM and the loop formation in pure Fe implanted with H+*

2011 ◽  
Vol 60 (3) ◽  
pp. 036802
Author(s):  
Huang Yi-Na ◽  
Wan Fa-Rong ◽  
Jiao Zhi-Jie
Keyword(s):  
Dislocation Loops ◽  
Loop Formation

Defect fine Structures as observed by in situ experiments

1990 ◽  
Vol 48 (4) ◽  
pp. 458-459
Author(s):  
H. Saka
Keyword(s):  
Tensile Stress ◽  
Materials Science ◽  
External Stress ◽  
Dislocation Loops ◽  
Irradiation Creep ◽  
In Situ Experiment ◽  
In Situ Experiments ◽  
Fine Structures ◽  
Edge Dislocations

An in-situ experiment in an electron microscope is now a well established and useful technique in materials science. In this review recent contributions of in-situ experiments, especially of straining and heating experiments, to materials science will be high-lighted.The earlier works have been reviewed by Saka and Imura.It is believed that an external stress gives rise to an anistropy in the rate at which point defects are absorbed by edge dislocations; this mechanism is considered to explain the irradiation creep. A combined in situ tensile/irradiation experiment in a HVEM has been carried out to study effects of applied stress on the growth of dislocation loops. Fig. 1 shows typical microstructures of Ag irradiated at 403K for 10 min with 1MV electrons in the absence (a), and in the presence of an external stress of 5.5 kg/mm2 (b). Frank loops of interstial type, formed by electron irradiation, grew more rapidly in the direction of the external tensile stress than in the others. These results show that an external tensile stress has a profound effect on climb rates of Frank loops of interstitial type. However, detailed analysis of the results indicates that there is a considerable discrepancy between experiment and theory.

A study on sink strength of dislocations through analyses of loop formation process under defect concentration gradient

1990 ◽  
Vol 48 (4) ◽  
pp. 528-529
Author(s):  
Kiyomichi Nakai ◽  
Chiken Kinoshita
Keyword(s):  
Void Formation ◽  
Nucleation And Growth ◽  
Dark Field ◽  
Sink Strength ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Dark Field Microscopy ◽  
Zr Alloy

The behavior of point defects around sinks has been greatly investigated for evaluating their bias effects on void formation and swelling. It is, however, laborious to estimate sink strength connected with the bias, because it depends greatly on the sink character. In the present paper the sink strength for interstitials is confirmed through analyses of nucleation and growth process of dislocation loops around characterized dislocations under electron irradiation.A Nb-40.0wt.%Zr alloy having the interface between bcc structures of βNb and βZr phases was irradiated with 1MeV electrons in the JEM-1000 high-voltage electron microscope at the HVEM Laboratory, Kyushu University.The orientation relationship between βNb and βZr phases follows the cube/cube, and the interfaces are. The interface dislocations run parallel to [111] and at a regular interval and respectively have Burgers vectors of b = 1/2 and 1/2[111]. Misfit between the phases as well as distance between interface dislocations are also confirmed by dark-field microscopy, trace analysis and electron diffraction.

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