Electronics properties of ZnSe nanotube with substitutional impurity atoms - A first-principles investigation

A theoretical study of isolated and doubly-clustered impurities is presented for the electronic excitations in a carbon nanotube lattice. Using a matrix operator formalism and a tight-binding model where the interactions between atoms take place via nearest-neighbor hopping, the properties of the excitations are deduced. A geometry consisting of long, single-walled carbon nanotubes is assumed with the defects introduced in the form of substitutional impurity atoms, giving rise to the localized electronic modes of the nanotube as well as the propagating modes of the pure (host) material. The impurities are assumed to be in a low concentration, having the form of either a single, isolated defect or a small cluster of two defects close together. A tridiagonal matrix technique is employed within a Green’s function formalism to obtain the properties of the discrete modes of the system, including their frequencies and localization. The numerical examples show a dependence on the nanotube diameters and on the relative spatial configurations of the impurities. The results contrast with the previous studies of line impurities since there is no translational symmetry along the longitudinal axis of the nanotubes in the present case.

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Properties of Iron Atoms at Grain Boundaries in Fe and Fe72Al28

MRS Proceedings ◽

10.1557/proc-527-273 ◽

1998 ◽

Vol 527 ◽

Cited By ~ 3

Author(s):

O. Schneeweiss ◽

I. Turek ◽

J. Čermák ◽

P. Lejček

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Single Crystals ◽

First Principles ◽

Magnetic Moments ◽

Emission Mössbauer Spectroscopy ◽

First Principles Calculations ◽

Hyperfine Parameters ◽

Impurity Atoms ◽

Atomic Spacing

ABSTRACTLocation of diffused 57Co atoms in single crystals, bicrystals and polycrystals of pure iron and Fe72Al28alloy were investigated by means of emission Mössbauer spectroscopy. To interpret the results, first principles calculations of iron atom magnetic moments and hyper-fine field were carried out. From comparison of M6ssbauer spectra of single crystals with those of bicrystals and polycrystals, an information about grain boundary positions occupied by diffusing atoms is obtained. It is shown that about 5% of the diffusing atoms at the {112} grain boundary of iron are located at the positions either having impurity atoms in the nearest neighbourhood or characterized by larger atomic spacing in comparison with the bulk. In the Fe72Al28 a dominating portion of diffusing atoms have different surrounding than in grain volume. An enrichment of grain boundaries by aluminum could explain their hyperfine parameters.

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First-principles investigation of dual substitutional impurity-induced electronic structural modulation of PbTe on cationic and anionic sites

Acta Materialia ◽

10.1016/j.actamat.2013.07.021 ◽

2013 ◽

Vol 61 (17) ◽

pp. 6428-6442 ◽

Cited By ~ 2

Author(s):

X.G. Wang ◽

J. Liu ◽

L.M. Peng

Keyword(s):

First Principles ◽

Anionic Sites ◽

Substitutional Impurity ◽

Structural Modulation

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The stability and diffusion properties of foreign impurity atoms on the surface and in the bulk of vanadium: A first-principles study

Computational Materials Science ◽

10.1016/j.commatsci.2013.08.011 ◽

2014 ◽

Vol 81 ◽

pp. 191-198 ◽

Cited By ~ 15

Author(s):

Ling Gong ◽

Qiulei Su ◽

Huiqiu Deng ◽

Shifang Xiao ◽

Wangyu Hu

Keyword(s):

First Principles ◽

Impurity Atoms ◽

First Principles Study ◽

The Stability ◽

And Diffusion ◽

Diffusion Properties

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Interaction of two substitutional impurity atoms in an hcp crystal

Low Temperature Physics ◽

10.1063/1.3388846 ◽

2010 ◽

Vol 36 (4) ◽

pp. 360-362 ◽

Cited By ~ 1

Author(s):

V. I. Belan ◽

A. I. Landau

Keyword(s):

Substitutional Impurity ◽

Impurity Atoms

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Effect of Impurities on the Electronic Structureof Grain Boundaries and Intergranular Cohesionin Tungsten

MRS Proceedings ◽

10.1557/proc-291-109 ◽

1992 ◽

Vol 291 ◽

Cited By ~ 1

Author(s):

Genrich L. Krasko

Keyword(s):

First Principles ◽

High Strength ◽

Interatomic Interaction ◽

Competition Effect ◽

Impurity Atoms ◽

Intergranular Embrittlement ◽

Effect Of Impurities ◽

Site Competition ◽

Semi Empirical ◽

Segregation Of Impurities

ABSTRACTThe cohesion of a grain boundary (GB) is believed to be the controlling factor limiting theductility of high-strength metallic alloys, and particularly W. Intergranular embrittlement isusually associated with segregation of impurities at the GBs. Impurities present in ppmconcentrations can result in a dramatic decrease in plasticity. This paper reviews recent results onboth semi-empirical and first-principles modelling of the energetics and the electronic structuresof impurities on a Σ3 (111) GB in W. Our calculations have shown that impurities, such as N, O,P, S, and Si weaken the intergranular cohesion resulting in “loosening” the GB. The presence ofB and C on the contrary, enhances the interatomic interaction across the GB. The so-called site-competition effect should play an important role affecting impurity distribution in W GBs.Among the impurities analyzed, B in the GB has the lowest energy, and thus would tend todisplace other impurity atoms from the GB. Microalloying with 10-50 ppm B may be an effectiveway of improving tungsten's ductility. These results are important for understanding thefundamental physics of intergranular embrittlement.

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Application of Channeling to Defect Studies in Crystals

MRS Proceedings ◽

10.1557/proc-2-117 ◽

1980 ◽

Vol 2 ◽

Author(s):

W. K. Chu

Keyword(s):

Defect Density ◽

Bond Distance ◽

Crystal Defects ◽

Structural Defects ◽

Substitutional Impurity ◽

Structure Information ◽

Surface And Interface ◽

Impurity Atoms ◽

Light Ions ◽

Fast Light

ABSTRACTChanneling of fast, light ions in crystals has been widely used as a tool for studying crystal defects. Backscattering yield measurement on ions incident along major axial or planar crystalline directions provides information on the depth distribution of the structural defects in the first few microns. The channeling technique in defect detection is not as sensitive as Transmission Electron Spectroscopy, nor is it accurate in measuring the absolute numbers of defect density. Channeling measurements can give only an indication of the degree of lattice disorder. It is possible to distinguish one type of defect from another by carefully studying the energy dependence of the dechanneling. The dechanneling interpretation is not always unique, and in practice it is difficult to obtain structure information through that method. Despite these negative qualities, channeling is an attractive and unique method in certain defect studies. For example, it is sensitive for studying the lattice location of impurity atoms at substitutional or interstitial sites. Clustering of substitutional impurity atoms will show a displacement of the impurity atoms from lattice sites due to the change of bond distance. Channeling is sensitive for measuring impurity displacement as small as 0.1A°. This has been demonstrated in the study of arsenic clustering formation in Si. Interfacial relaxation and contraction in a multi-layered structure made by molecular beam epitaxy has been detected by dechanneling along various axial directions. Channeling study on surface and interface structures has developed over the past few years. In this paper, I will use examples to illustrate the unique features of the channeling technique and its application to defect studies in single crystals.

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