scholarly journals Dependence of track etching kinetics on chemical reactivity around the ion path

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. A. Gorbunov ◽  
R. A. Rymzhanov ◽  
A. E. Volkov
Keyword(s):  
Chemical Reactivity ◽  
Quantitative Description ◽  
Sample Surface ◽  
Numerical Approach ◽  
Heavy Ion ◽  
Ion Trajectory ◽  
Track Etching ◽  
Wet Chemical ◽  
Kinetics Of ◽  
Account Variation

Abstract Etching kinetics of swift heavy ions (SHI) tracks in olivine is investigated in frame of experimentally verified numerical approach. The model takes into account variation of induced chemical reactivity of the material around the whole ion trajectory with the nanometric accuracy. This enables a quantitative description of wet chemical etching of SHI tracks of different lengths and orientations towards to the sample surface. It is demonstrated that two different modes of etching, governed by diffusion of etchant molecules and by their reaction with the material must be observed in experiments using techniques with different resolution thresholds. Applicability limits of the optical microscopy for detection of heavy ion parameters by measuring of the lengthwise etching rates of the ion track are discussed.

High-resolution observations of metastable γ’ precipitation in Al-15at.%Ag

1996 ◽  
Vol 54 ◽  
pp. 1004-1005
Author(s):  
N. V. Larcher ◽  
I. G. Solorzano
Keyword(s):  
Discontinuous Precipitation ◽  
Equilibrium Phase ◽  
Quantitative Description ◽  
Present Contribution ◽  
Α Phase ◽  
The Matrix ◽  
Aging Sequence ◽  
Matrix Precipitation ◽  
Considerable Detail ◽  
Kinetics Of

It is currently well established that, for an Al-Ag alloy quenched from the α phase and aged within the metastable solvus, the aging sequence is: supersaturated α → GP zones → γ’ → γ (Ag2Al). While GP zones and plate-shaped γ’ are metastable phases, continuously distributed in the matrix, formation of the equilibrium phase γ takes place at grain boundaries by discontinuous precipitation (DP). The crystal structure of both γ’ and γ is hep with the following orientation relationship with respect to the fee α matrix: {0001}γ′,γ // {111}α, <1120>γ′,γ, // <110>α.The mechanisms and kinetics of continuous matrix precipitation (CMP) in dilute Al-Ag alloys have been studied in considerable detail. The quantitative description of DP kinetics, however, has received less attention. The present contribution reports the microstructural evolution resulting from aging an Al-Ag alloy with Ag content higher than those previously reported in the literature, focusing the observations of γ' plate-shaped metastable precipitates.

CORRELATION BETWEEN ELECTRIC CHARGING OF THE SAMPLE SURFACE AND KINETICS OF OPTICALLY STIMULATED EXOELECTRON EMISSION (OSEE) FROM CRYOSOLIDIFIED NaCl SOLUTION

1990 ◽  
Vol 04 (03) ◽  
pp. 201-209
Author(s):  
A. GIEROSZYŃSKI
Keyword(s):  
Electric Fields ◽  
Surface Potential ◽  
Surface Region ◽  
Sample Surface ◽  
Exoelectron Emission ◽  
Nacl Solution ◽  
Emitter Surface ◽  
Emitter Layer ◽  
The Relationship ◽  
Kinetics Of

It was found that OSEE kinetics from electron bombarded cryosolidified NaCl solution, depend on electric charging of the sample surface. It was shown that from the relationship between the maximum surface potential and the parameters of OSEE kinetic, intensities of electric fields in the emitter layer could be estimated. It is supposed that nonhomogeneous electric fields existing in the emitter surface region, influence the emission levels responsible for the course of OSEE kinetics.

Phases Transformations in Laser Treated Hydroxyapatite Coatings

1998 ◽  
Author(s):  
X. Ranz ◽  
T. Aslanian ◽  
L. Pawlowski ◽  
L. Sabatier ◽  
R. Fabbro
Keyword(s):  
Titanium Alloy ◽  
Sample Surface ◽  
Optical Microscope ◽  
Thermal Fields ◽  
Hydroxyapatite Coatings ◽  
Titanium Alloy Substrate ◽  
Plasma Sprayed ◽  
Different Content ◽  
Kinetics Of ◽  
Xrd Method

Abstract The hydroxyapatite Ca10(PO4)6OH2 (HAP) was plasma sprayed onto titanium alloy substrate. The samples having thickness of about 150 µm ware sprayed in a way to obtain two different content of crystalline HAP: 25 an 30 %. The coatings ware subsequently submitted to laser treatment with the CO2 laser. The treatment was carried out with different laser powers and scanning velocities and resulting thereof sample surface temperatures and the kinetics of the thermal fields ware monitored with a pyrometer. The XRD method enabled verification of the crystallinity state of HAP, content of amorphous calcium phosphate and the content of foreign phases. Optical microscope was used to check the microstructure and the depth of laser modified zone.

Long-range electron–electron interaction and charge transfer in protein complexes: a numerical approach

2019 ◽  
Vol 21 (34) ◽  
pp. 18595-18604 ◽  
Author(s):  
David Gnandt ◽  
Thorsten Koslowski
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Protein Complexes ◽  
Numerical Approach ◽  
Pair Approximation ◽  
Electron Interaction ◽  
Coulomb Interactions ◽  
Electron Transfer Proteins ◽  
Thermodynamics And Kinetics ◽  
Kinetics Of

Coulomb interactions in large electron transfer proteins can be addressed within a pair approximation. They have a profound effect on the thermodynamics and kinetics of charge transport.

Comparison of the Chemical Reactivity and Bioactivity of Two Bioactive Glasses 47S6 and 48S4

2008 ◽  
Vol 396-398 ◽  
pp. 107-110 ◽  
Author(s):  
Hassane Oudadesse ◽  
M. Mami ◽  
R. Dorbez-Sridi ◽  
P. Pellen-Mussi ◽  
F. Perez ◽  
...  
Keyword(s):  
Mineral Composition ◽  
Chemical Reactivity ◽  
Rapid Quenching ◽  
Structural Basis ◽  
In Vitro Experiments ◽  
Layer Formation ◽  
Bioactive Glasses ◽  
Ionic Exchanges ◽  
Kinetics Of

This work is focused on the bioactive glasses obtained by melting and rapid quenching. Two glasses with mineral composition of: 47% SiO2 - 26% CaO - 21% Na2O - 6% P2O5 and 48% SiO2 - 30% CaO - 18% Na2O - 4% P2O5 were investigated. The aim of this study was to establish the kinetics of HCAp layer formation “in vitro” and to control the adhesion and proliferation cells of the two glasses in contact with osseous cells. Obtained results permit to evaluate their chemical reactivity and their bioactivity after immersion in the SBF-K9. Ionic exchanges between biomaterials and SBF liquid during the “in vitro” experiments highlight the differences of the chemical reactivity and bioactivity of 47S6 and 48S4. The structural basis for the effect of cristallinity on the rates of HCA formation in vitro in favour of glasses was also established. The melt derived 47S6 and 48S4 glasses offer to surgeons new compositions with different bioactivity kinetic that bioglassÒ 45S6 and can be adaptable in some other bony pathology.

Defect Etching of Non-Polar and Semi-Polar Faces in SiC

2007 ◽  
Vol 556-557 ◽  
pp. 243-246
Author(s):  
Sakwe Aloysius Sakwe ◽  
Yeon Suk Jang ◽  
Peter J. Wellmann
Keyword(s):  
Chemical Etching ◽  
Structural Defects ◽  
Surface Polarity ◽  
Applied Method ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Etching Parameters ◽  
Kinetics Of

Wet chemical etching using molten KOH is the most frequently applied method to reveal structural defects in SiC. Until now etching kinetics of SiC in planes different from the polar cplane has not been reported. In this paper we report on defect etching of SiC in non-polar faces. Using a calibrated KOH defect-etching furnace with possibilities to set accurate etching temperatures we have etched SiC samples of various orientations to (i) study defect occurrence and their morphologies (ii) set KOH defect etching parameters for SiC for these orientations and (iii) investigate etching kinetics in relation to anisotropy/surface polarity. For non-polar planes of the same orientations a comparison in etching kinetics and defect morphologies in crystals grown in different directions is presented.

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