Computer Simulation of Point Defects in Hexagonal Close Packed Metals

1988 ◽  
Vol 141 ◽  
Author(s):  
Eduardo J. Savino ◽  
Ana M. Monti
Keyword(s):  
Harmonic Approximation ◽  
Site Occupancy ◽  
Lattice Relaxation ◽  
Pair Interaction ◽  
Interstitial Site ◽  
Lattice Parameter ◽  
Rigid Sphere ◽  
Perfect Lattice ◽  
Spline Fitting ◽  
The Stability

AbstractPair interaction potentials have been developed by spline fitting cubic functions to reproduce perfect lattice properties. The lattice symmetry is taken as hcp with the rigid sphere c/a ratio and a cut-off distance between second and third neighbor is assumed. The lattice parameter, elastic constants and vacancy formation energy of Mg, Ti and Zr are consistently fitted by the potentials. We have calculated the lattice relaxation predicted by these potentials for the vacancy, and self interstitial in an otherwise perfect hcp lattice. The stability and dynamics of those defects are studied within the quasi-harmonic approximation. The interstitial site occupancy in hcp lattice and the vacancy and interstitial diffusion are discussed.

Electronic Structure of Li-Impurities in ZnSe.

1989 ◽  
Vol 163 ◽  
Author(s):  
T. Oguchi ◽  
T. Sasaki ◽  
H. Katayama-Yoshida
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Local Density ◽  
Lattice Relaxation ◽  
Interstitial Site ◽  
Functional Approach ◽  
Tetrahedral Interstitial Site ◽  
Total Energies ◽  
The Stability ◽  
Impurity Sites

AbstractElectronic properties of ZnSe with a Li impurity are investigated with use of the local-density-functional approach. The electronic structures are calculated for different impurity sites by taking the neighboring lattice relaxation into account. By comparing their total energies, the stability of the Li impurity in ZnSe is discussed. It is proposed that the Li impurity at the substitutional Zn site might be unstable to the tetrahedral interstitial site with an ionization of Li and a vacancy at the Zn site.

Effect of Additives on the Phase Equilibria Related to the E21-Fe3AlC Intermetalic Compound with Carbon Atom at the Interstitial Site

2002 ◽  
Vol 753 ◽  
Author(s):  
Hiroaki Ishii ◽  
Seiji Miura ◽  
Tetsuo Mohri
Keyword(s):  
Lattice Constant ◽  
Lattice Misfit ◽  
Interstitial Site ◽  
Lattice Parameter ◽  
The Body ◽  
Study Phase ◽  
Two Phase ◽  
Octahedral Interstitial Site ◽  
The Stability ◽  
Alloys And Compounds

ABSTRACTThe structure of E21 is a derivative of L12 structure with an interstitial carbon in the body center or the octahedral interstitial site. In the Fe-Al-C ternary system E21-Fe3AlC intermetallic is known to precipitate in γ-austenite alloys. For the high temperature application, the stability of microstructure is a key issue and the control of the lattice misfit is essential. By adding some elements to Fe-Al-C alloys, the lattice constant can be controlled, and enhancement of the stability of γ-austenite + E21-Fe3AlC two phase structure is expected. In this study, phase stability and lattice parameter of E21 phase in the (Fe-Mn)-(Al-M)-C system (M=Si, Ge) are investigated. In both systems, no significant changes in microstructures were observed within the composition range of concern. The lattice constant of E21-Fe3AlC phase, however, does not show decrease with the addition of Si or Ge. This result is different from what was expected. By WDS analysis, it was revealed that Si tends to distribute mainly in γ phase, and Ge concentrates in E21-Fe3AlC phase. It was found that the lattice constants of E21 phases are very close to those of L12 structure estimated from the atomic radii of constituent elements which are evaluated from those in binary alloys and compounds. The distribution behavior of Si and Ge can be related to tolerance factor which strongly affects the stability of phases.

MÖSSBAUER STUDY OF HYDROGEN DIFFUSION AND INTERSTITIAL SITE OCCUPANCY IN57Co : PdHxAND57Fe : PdHx

1979 ◽  
Vol 40 (C2) ◽  
pp. C2-635-C2-638
Author(s):  
F. Pröbst ◽  
F. E. Wagner ◽  
M. Karger ◽  
G. Wortmann
Keyword(s):  
Hydrogen Diffusion ◽  
Site Occupancy ◽  
Interstitial Site ◽  
Mössbauer Study

Discovery of an Environmentally Friendly Water-Soluble Luminous Material with Interstitial Site Occupancy

2021 ◽  
Vol 9 (7) ◽  
pp. 2717-2726
Author(s):  
Jinyu Wang ◽  
Tianchun Lang ◽  
Shuangqiang Fang ◽  
Tao Han ◽  
Mingsheng Cai ◽  
...  
Keyword(s):  
Site Occupancy ◽  
Environmentally Friendly ◽  
Interstitial Site ◽  
Water Soluble

scholarly journals Crystallographic, Energy Gap, Photoluminescence and Photo-Catalytic Investigation of Cu Doped Cd0.9Zn0.1S Nanostructures by Co-Precipitation Method

2021 ◽  
Author(s):  
P. Raju ◽  
Joseph Prince Jesuraj ◽  
S. Muthukumaran
Keyword(s):  
Crystallite Size ◽  
Energy Gap ◽  
Wavelength Region ◽  
Lattice Parameter ◽  
Precipitation Method ◽  
Optical Absorbance ◽  
Stability Measurement ◽  
Cubic Structure ◽  
The Stability ◽  
Co Precipitation

Abstract The controlled synthesis of Cd0.9Zn0.1S, Cd0.89Zn0.1Cu0.01S and Cd0.87Zn0.1Cu0.03S nanostructures by simple chemical co-precipitation technique was reported. The XRD investigation confirmed the basic CdS cubic structure on Zn-doped CdS and also Zn, Cu dual doped CdS with no secondary/impurity related phases. No modification in cubic structure was detected during the addition of Zn/Cu into CdS. The reduction of crystallite size from 63 Å to 40 Å and the changes in lattice parameter confirmed the incorporation of Cu into Cd0.9Zn0.1S and generation of Cu related defects. The shift of absorption edge along upper wavelength region and elevated absorption intensity by Cu doping can be accredited to the collective consequence of quantization and the generation of defect associated states. The enhanced optical absorbance and the reduced energy gap recommended that Cd0.87Zn0.1Cu0.03S nanostructure is useful to enhance the efficiency of opto-electronic devices. The presence of Cd-S / Zn-Cd-S /Zn/Cu-Cd-S chemical bonding were confirmed by Fourier transform infrared investigation. The elevated green emissions by Cu incorporation was explained by decrease of crystallite size and creation of more defects. Zn, Cu dual doped CdS nanostructures are recognized as the possible and also efficient photo-catalyst for the removal dyes like methylene blue. The enhanced photo-catalytic behaviour of Zn, Cu dual doped CdS is the collective consequences of high density electron-hole pairs creation, enhanced absorbance in the visible wavelength, surface area enhancement, reduced energy gap and the formation of novel defect associated states. The stability measurement signified that Cu doped Cd0.9Zn0.1S exhibits superior dye removal ability and better stability even after 6 repetitive runs with limited photo-corrosion.

A Brief Introduction to Alloy Phase Chemistry Determination under EPMA/SEM-EDS Conditions and its Applications

2012 ◽  
Vol 706-709 ◽  
pp. 2450-2455 ◽  
Author(s):  
Zhi Fang Peng ◽  
Li Sheng Cai ◽  
Ying Ying Dang ◽  
Lei Zhao ◽  
Fang Fang Peng ◽  
...  
Keyword(s):  
Site Occupancy ◽  
Lattice Parameter ◽  
Structure Property ◽  
Heat Resistant Steel ◽  
Surrounding Matrix ◽  
Structure Property Relationships ◽  
Precipitated Phases ◽  
Phase Chemistry ◽  
Physical Quantities ◽  
Accurate Quantification

A so called multiphase separation method (MPSM) is proposed to quantitatively separate precipitated phases from their surrounding matrix phase in chemistry for bulk alloy/steel samples under EPMA/SEM-EDS measurement conditions. Applied examples to comparisons of the results through the MPSM with the values either cited or obtained via other analytical means relevant are indicative of the feasibility, accuracy as well as applicability of the MPSM, which deal with chemistry, amount, lattice parameter, elemental partitioning, atomic-site occupancy and stability of precipitated phases of either superalloy or heat-resistant steel samples analyzed. Successful applications of the MPSM not only show a significant improvement for difficulties in accurate quantification in phase chemistry under the EPMA/SEM-EDS measurement conditions but also provide with a useful and helpful tool to determine some other important physical quantities in alloys and steels, which make it possible to quantitatively and more widely evaluate structure-property relationships of the materials investigated through analyzing their bulk samples under EPMA/SEM-EDS measurement conditions.

An analogy of interstitial site occupancy and hydrogen induced disproportionation of Zr 1−x Ti x Co ternary alloys

2017 ◽  
Vol 42 (12) ◽  
pp. 8089-8097 ◽  
Author(s):  
Ram Avtar Jat ◽  
Ripandeep Singh ◽  
Subhasis Pati ◽  
P.U. Sastry ◽  
A. Das ◽  
...  
Keyword(s):  
Site Occupancy ◽  
Interstitial Site ◽  
Ternary Alloys

Prediction of site occupancy of C15 Laves phase at finite temperature based on quasi-harmonic approximation model

2018 ◽  
Vol 96 ◽  
pp. 33-40 ◽  
Author(s):  
Zhenyi Wei ◽  
Yixu Yang ◽  
Jinchang Huang ◽  
Bo Wu ◽  
Baisheng Sa ◽  
...  
Keyword(s):  
Finite Temperature ◽  
Harmonic Approximation ◽  
Site Occupancy ◽  
Laves Phase ◽  
Approximation Model

The effect of Ru on Ti50Pd50 high temperature shape memory alloy: a first-principles study

MRS Advances ◽  
2019 ◽  
Vol 4 (44-45) ◽  
pp. 2419-2429 ◽  
Author(s):  
R. G. Diale ◽  
R. Modiba ◽  
P. E. Ngoepe ◽  
H. R. Chauke
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Lattice Parameter ◽  
Heat Of Formation ◽  
Partial Substitution ◽  
Martensitic Transformation Temperature ◽  
Functional Theory ◽  
Equilibrium Lattice Parameter ◽  
Strengthening Element ◽  
The Stability

ABSTRACTThe stability of the Ti50Pd50-xRux alloy was investigated using first-principles density functional theory within the plane-wave pseudopotential method. Firstly, the Ti50Pd50 gave equilibrium lattice parameter and lowest heats of formation in better agreement with experimental data to within 3%. The heat of formation decreases with an increase in Ru concentration, consistent with the trend of the density of states which is lowered at the Fermi level as Ru content is increased which suggests stability. It was also found that from the calculated elastic constants the structures showed positive shear modulus above 20 at. % Ru, condition of stability. Furthermore, the addition of Ru was found to strengthen the Ti50Pd50-xRux system at higher concentrations. The thermal coefficients of linear expansion for the Ti50Pd31.25Ru18. 75 are higher at low temperature, and that the TiPd-Ru system tends to expand more at low content of 18.75 at. % Ru than at higher content. Partial substitution of Pd with Ru was found more effective as a strengthening element and may enhance the martensitic transformation temperature of the Ti50Pd50 alloy.

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