Vacancy cluster-induced local disordered structure for the enhancement of thermoelectric property in Cu2ZnSnSe4

2021 ◽  
Author(s):  
Zhou Li ◽  
Weihui Zhang ◽  
Bingchuan Gu ◽  
Chenxi Zhao ◽  
Bangjiao Ye ◽  
...  
Keyword(s):  
Thermoelectric Property ◽  
Vacancy Cluster ◽  
Thermoelectric Performance ◽  
Vacancy Clusters ◽  
Disordered Structure ◽  
Local Disorder

Local disorder induced by vacancy clusters containing cation and intrinsic Se vacancies servers as thermoelectric performance booster in cation-deficient Cu2ZnSnSe4.

Large reduction of thermal conductivity leading to enhanced thermoelectric performance in p-type Mg3Bi2–YbMg2Bi2 solid solutions

2019 ◽  
Vol 7 (2) ◽  
pp. 434-440 ◽  
Author(s):  
Ting Zhou ◽  
Jun Mao ◽  
Jing Jiang ◽  
Shaowei Song ◽  
Hangtian Zhu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Thermoelectric Property ◽  
Solid Solutions ◽  
Thermoelectric Performance ◽  
Large Reduction ◽  
P Type

The thermoelectric property of YbMg2Bi2–Mg3Bi2 solid solution is studied.

Strain-Rate Dependence of Vacancy Cluster Size in Hydrogen-Charged Martensitic Steel AISI410 under Tensile Deformation

2017 ◽  
Vol 373 ◽  
pp. 171-175 ◽  
Author(s):  
Kazuki Sugita ◽  
Yasumasa Mutou ◽  
Yasuharu Shirai
Keyword(s):  
Strain Rate ◽  
Positron Lifetime ◽  
Tensile Deformation ◽  
Martensitic Steel ◽  
Vacancy Cluster ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Strain Rates ◽  
Vacancy Clusters ◽  
Positron Lifetime Spectroscopy

The strain-rate dependence of vacancy cluster sizes in hydrogen-charged martensitic steel AISI410 under tensile deformation was investigated using positron lifetime spectroscopy. The vacancy-cluster sizes in hydrogen-charged samples tended to increase with decreasing strain rates during the tensile deformations. The vacancy-cluster sizes significantly correlated to the tensile elongations to fracture. It was revealed that the presence of large-sized vacancy-clusters can cause the degradation of mechanical properties and followed by brittle fracture.

Deformation-induced vacancy-type defects in GaAs

1991 ◽  
Vol 69 (3-4) ◽  
pp. 298-306 ◽  
Author(s):  
P. Mascher ◽  
S. Dannefaer ◽  
D. Kerr
Keyword(s):  
Isothermal Annealing ◽  
Positron Lifetime ◽  
Total Concentration ◽  
Vacancy Cluster ◽  
Void Size ◽  
Shallow Trap ◽  
Vacancy Clusters ◽  
Positron Lifetime Spectroscopy ◽  
Average Size ◽  
Shallow Traps

Semi-insulating undoped GaAs was plastically deformed and then investigated by positron-lifetime spectroscopy. Strains between 0 and 40% and temperatures of deformation of 450, 500, and 600 °C were investigated, with detailed investigations carried out for the lowest temperature of deformation. Between 0 and 4% strain, a reduction of the grown-in vacancy response takes place simultaneously with a slight increase in vacancy cluster size to two or three vacancies. Between 4 and 6% strain a very substantial increase in vacancy production occurs but nearly all of these vacancies are clustered into voids with a radius of about 50 Å (1 Å = 10−10 m) and density in the order of 1013–1014 cm−3. The total concentration of vacancies necessary to produce these voids is 1017–1018 cm−3. This clearly shows that vacancies are formed upon deformation and that they are mobile at 450 °C. Upon further deformation to 20% strain, the overall defect concentration becomes so high that all positrons become trapped for which reason no absolute defect concentrations can be deduced. The dominant defect types can nevertheless be identified as voids (of average size of 20 Å), two- or three-vacancy clusters, and shallow traps. Isothermal annealing of 40% strained samples shows that heat treatment reduces the void concentration but increases the average void size, and results only in a small decrease in shallow-trap concentration. The shallow traps are likely the dislocation lines themselves and the small vacancy clusters appear to be associated with the dislocation lines.

Simulation of Vacancy Cluster Formation and Binding Energies in Single Crystal Germanium

2007 ◽  
Vol 994 ◽  
Author(s):  
Piotr Spiewak ◽  
Krzysztof Jan Kurzydlowski ◽  
Jan Vanhellemont ◽  
Piotr Wabinski ◽  
Krzysztof Mlynarczyk ◽  
...  
Keyword(s):  
Single Crystal ◽  
Cluster Formation ◽  
Vacancy Cluster ◽  
Growth Patterns ◽  
Binding Energies ◽  
Effective Surface ◽  
Vacancy Clusters ◽  
Molecular Dynamics Calculations ◽  
Weber Potential ◽  
Effective Surface Energy

AbstractResults are presented of the simulation of the properties of vacancy clusters in single crystal germanium. Classical molecular dynamics calculations based on a Stillinger and Weber potential were used in a theoretical investigation of different growth patterns of vacancy clusters Vi. The formation and binding energies of vacancy clusters have been studied in the range 1 ≤ i ≤ 35. The energetically favourable growth mode and an estimate of the effective surface energy was determined for a vacancy clusters containing up to 35 vacancies

Growth of Vacancy Clusters During Post-Irradiation Annealing of Ion Implanted Silicon,

1995 ◽  
Vol 396 ◽  
Author(s):  
A. van Veen ◽  
H. Schut ◽  
A. Rivera ◽  
A.V. Fedorov
Keyword(s):  
Cavity Growth ◽  
Positron Beam ◽  
Vacancy Cluster ◽  
High Dose ◽  
High Concentration ◽  
Vacancy Clusters ◽  
Dissociation Energies ◽  
Beam Analysis ◽  
Growth Barriers ◽  
Silicon Based

AbstractAnnealing experiments of deuterium implanted silicon have been performed while positron beam analysis was used for monitoring the cavity growth. The experiments indicate up to annealing temperature 500° C similar defect evolution for both the low dose of 1016 cm-2 as for a 3 times higher dose. At this temperature the deuterium stabilized vacancy clusters dissociate and only in the case of the high dose micro-cavities are formed. Monte Carlo simulations of vacancy cluster growth in silicon based on vacancy cluster dissociation energies, calculated with the Stillinger Weber potential, have been performed. The results indicate that for low initial defect concentrations vacancy clusters might be hindered to grow because the vacancy binding energy of the clusters does not increase monotonically with the cluster size. Only a high concentration guarantees that growth barriers will be overcome.

Temperature and Strain Rate Dependence of Deformation-Induced Point Defect Cluster Formation in Metal Thin Foils

2001 ◽  
Vol 673 ◽  
Author(s):  
K. Yasunaga ◽  
Y. Matsukawa ◽  
M. Komatsu ◽  
M. Kiritani
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Cluster Formation ◽  
Vacancy Cluster ◽  
Long Tail ◽  
Vacancy Clusters ◽  
Thin Foils ◽  
Lower Strain ◽  
Wide Range ◽  
Deformation Speed

ABSTRACTThe mechanism of plastic deformation in thin metal foils without involving dislocations was examined by investigating the variations in vacancy cluster formation during deformation for a range of deformation speeds and temperatures. The deformation morphology was not seen to change appreciably over a very wide range of strain rate, 10-4/s – 106/s, whereas the number density of vacancy clusters was observed to increase with increasing strain rate up to saturation value that is dependent on materials and temperature. The density of vacancy clusters decreased to zero with decreasing deformation speed. The strain rate at which the density of vacancy clusters begins to decrease was found to be proportional to the vacancy mobility, suggesting that the vacancies are generated as dispersed vacancies and escape to the specimen surfaces during slow deformation without forming clusters. A very long tail in the distribution of the density of vacancy clusters towards lower strain rates was reasonably attributed to the generation of small vacancy complexes due to deformation. These results give valuable information that can be used to establish new models for plastic deformation of crystalline metals without involving dislocations.

Diffraction Contrast of Small Vacancy Clusters in Silicon

1970 ◽  
Vol 28 ◽  
pp. 514-515 ◽  
Author(s):  
T. J. Magee ◽  
R. H. Morriss
Keyword(s):  
Electron Diffraction ◽  
Differential Equations ◽  
Vacancy Cluster ◽  
Dynamical Theory ◽  
Integration Scheme ◽  
Thin Sample ◽  
Vacancy Clusters ◽  
Diffraction Contrast ◽  
Exit Surface ◽  
The Many

Diffraction contrast profiles have been examined utilizing the two beam dynamical theory for a thin sample containing a spherical vacancy cluster. The differential equations describing electron diffraction amplitudes in an absorbing crystal have been given by Howie and Whelan and the strain parameter for a center of dilation in a semi-infinite solid has been derived by Mindlin and Cheng. Using a Runge-Kutta integration scheme, the contrast equations were solved numerically to yield the intensities of the transmitted and scattered beams at the exit surface of the foil. In all computations, the many beam 220 extinction distance of 723 Å was used in predicting contrast profiles.

Change in the Positron Annihilation Lifetime of Vacancy Clusters Containing Hydrogen Atoms in Electron-Irradiated F82H

2021 ◽  
Vol 1024 ◽  
pp. 71-78
Author(s):  
Koichi Sato ◽  
Yohei Kondo ◽  
Masakiyo Ohta ◽  
Qiu Xu ◽  
Atsushi Yabuuchi ◽  
...  
Keyword(s):  
Theoretical Calculation ◽  
Positron Annihilation ◽  
Room Temperature ◽  
Vacancy Cluster ◽  
Hydrogen Atoms ◽  
Positron Annihilation Lifetime ◽  
Vacancy Clusters ◽  
Hydrogen Charging ◽  
Trapping Effect ◽  
Before And After

The change in the positron annihilation lifetime (PAL) of vacancy clusters before and after electrolysis hydrogen charging was determined using PAL measurements in electron-irradiated F82H. The experimental change indicated 8 hydrogen atoms were trapped in vacancy clusters; whereas the theoretical calculation resulted in approximately 14 atoms. As the samples were left at room temperature for 5 min until the start of the PAL measurements, the de-trapping effect of hydrogen atoms was also considered; approximately 13 hydrogen atoms were captured at each vacancy cluster. The PAL decreased after annealing at 148 K, which could not be explained theoretically. Therefore, further experiments and discussions are needed to obtain a precise change in the PAL of vacancy clusters containing hydrogen atoms in F82H.

scholarly journals Numerical Interpretation of Hydrogen Thermal Desorption Spectra for Iron with Hydrogen-Enhanced Strain-Induced Vacancies

2020 ◽  
Vol 52 (1) ◽  
pp. 257-269
Author(s):  
Ken-ichi Ebihara ◽  
Yuri Sugiyama ◽  
Ryosuke Matsumoto ◽  
Kenichi Takai ◽  
Tomoaki Suzudo
Keyword(s):  
Thermal Desorption ◽  
Vacancy Cluster ◽  
Hydrogen Atoms ◽  
High Temperature Side ◽  
Vacancy Clusters ◽  
Static Calculation ◽  
Iron Specimen ◽  
Atomistic Calculations ◽  
Enhanced Strain ◽  
Temperature Side

AbstractWe obtained thermal desorption spectra of hydrogen for a small-size iron specimen to which strain was applied during charging with hydrogen atoms. In the spectra, a shoulder-shaped peak in the high-temperature side was enhanced compared with the spectra of the specimen to which only strain was applied. We also observed that the peak almost disappeared by aging processes at ≥ 373 K. Then, assuming that the shoulder-shaped peak results from hydrogen atoms released by vacancies, we simulated the thermal desorption spectra using a model incorporating the behavior of vacancies and vacancy clusters. The model considered up to vacancy cluster $${{V_9}}$$ V 9 , which is composed of nine vacancies, and employed the parameters based on atomistic calculations, including the H trapping energy of vacancies and vacancy clusters that we estimated using the molecular static calculation. As a result, we revealed that the model could, on the whole, reproduce the experimental spectra, except two characteristic differences, and also the dependence of the spectra on the aging temperature. By examining the cause of the differences, the possibilities that the diffusion of clusters of $${V_2}$$ V 2 and $${V_3}$$ V 3 is slower than the model and that vacancy clusters are generated by applying strain and H charging concurrently were indicated.

Multiscale Modeling of Helium-Vacancy Cluster Nucleation under Irradiation: A Kinetic Monte-Carlo Approach

2009 ◽  
Vol 1215 ◽  
Author(s):  
Tomoaki Suzudo ◽  
Masatake Yamaguchi ◽  
Hideo Kaburaki ◽  
Ken-ichi Ebihara
Keyword(s):  
Monte Carlo ◽  
Ab Initio ◽  
Point Defects ◽  
Kinetic Monte Carlo ◽  
Monte Carlo Model ◽  
Vacancy Cluster ◽  
Austenitic Steels ◽  
Vacancy Clusters ◽  
Dissociation Energies ◽  
Object Kinetic Monte Carlo

AbstractWe applied ab initio calculation and an object kinetic Monte Carlo modeling to the study of He-vacancy cluster nucleation under irradiation in bcc and fcc Fe, which are surrogate materials for ferritic/martensitic and austenitic steels, respectively. The ab initio calculations provided parameters for the object kinetic Monte Carlo model, such as the migration energies of point defects and the dissociation energies of He and vacancy to He-vacancy clusters. We specially focused on the simulation of high He/dpa irradiation such as He-implantation into the materials and tracked the nucleation of clusters and the fate of point defects such as SIAs, vacancies, and He atoms. We found no major difference of He-vacancy cluster nucleation between bcc and fcc Fe when we ignore the intracascade clustering even if the migration energies of point defects are significantly different between the two crystals.

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