In materials science, a dislocation (line defect) represents a linear crystallographic defect within the crystal structure, which causes an abrupt change in the arrangement of atoms, which in turn influences several properties of materials. The dislocation density is a measure of the number of dislocations in a unit volume of a crystalline material usually having unit of lines per square meter (lines/m2).
Voids, pinholes, cracks, or inclusions like bulk defects are the macroscopic regions, where there are no atoms and which can be thought of as clusters of vacancies. Usually, bulk defect density has the unit of per cubic centimeter (cm-3).
However, I would be highly obliged if any scholar provides me articles or mathematical equations (if any) to relate the dislocation density to the bulk defect density.
Thanks in advance.
https://www.mdpi.com/1996-1944/12/24/4205/pdf
https://www.mdpi.com/1996-1944/12/13/2207/pdf
For the determination of the bulk dislocation density, it's better to go with the XRD/neutron diffraction-based technique. You may have a look at this article.
Hope this helps.
Dear Md Mahabub
The dislocation, i.e., line defect, density is the bulk defect density.
Naturally, there is a point bulk defects, i .e., interstitial and substitutional atoms .
Also, there is a planar (has 2-D) bulk defect, i.e., a stacking fault, in some solid metals and alloys.
https://www.mdpi.com/1996-1944/12/24/4205/pdf
https://www.mdpi.com/1996-1944/12/13/2207/pdf
A Comparative Study of Dislocations in HVPE GaN Layers by High-Resolution X-Ray Diffraction and Selective Wet Etching
Article A Comparative Study of Dislocations in HVPE GaN Layers by Hi...
Dear Dr. Md. Mahabub Alam Moon,
I suggest you to have a look at the following, interesting papers:
-Defects in Monocrystalline Silicon
Wilfried von Ammon, Andreas Sattler, Gudrun Kissinger
in: Kasap S., Capper P. (eds) Springer Handbook of Electronic and Photonic Materials. Springer Handbooks. Springer, Cham. https://doi.org/10.1007/978-3-319-48933-9_5 (2017)
Available at: https://link.springer.com/chapter/10.1007/978-3-319-48933-9_5#citeas
- Uprooting defects to enable high-performance III–V optoelectronic devices on silicon
Bioud, Y.A., Boucherif, A., Myronov, M. et al.
Nature Communications 10, 4322 (2019)
Available at: https://www.nature.com/articles/s41467-019-12353-9
Good work and best regards, Pierluigi Traverso
Dear Md. Mahabub Alam Moon, You say “In materials science, a dislocation (line defect) represents a linear crystallographic defect within the crystal structure, which causes an abrupt change in the arrangement of atoms, which in turn influences several properties of materials.”
In fact, your statement suppose more or less the notion of perfect crystal, but consider the cubic crystals:
The crystal structures are determined from their X-ray, electrons or neutrons diffraction patterns. The interpretation of these patterns uses the symmetry of the point groups where the atomic positions are considered as points. From this point of view, the atomic dissymmetry is ignored. However, from a strict geometrical approach with dissymmetric atoms, it is useful to underline that the cube would not be exhibited as a crystal structure. Indeed, in a cube there are four body diagonals, which link two by two, two opposite apexes. Yet there is no strictly periodic lattice built with non-spherical objects able to make identical the four diagonal of a hexahedron. If we search to build an arrangement with three equivalent directions; in a first step, we will put together the atoms in planes since we will stack up them, thus we can build three diagonals of the cube but the fourth has its properties determined by those of the three others. For example, it will be the easy direction of magnetization in some cubic magnetic compounds, a difficult difference to detect on a nom magnetic aspect. Nevertheless if we still observe cubic structures this comes from a small disorder, which is sufficient to maintain the cubic structure, the atomic dissymmetry being too small to generate a corresponding structure. From experiments the disorder is revealed in the mosaic structure of the crystals; Guinier thus conclude a discussion on the crystal perfection "In the majority of the cases, the ideally imperfect crystal is a better approximation than the perfect crystal" [A. Guinier, « Théorie et technique de la radiocristallographie », Dunod, Paris (1956) p.141. This book exists also in English]. See “Atoms and Crystal Structures” and “About of the limit of validity of the point groups' theory” on my site.
The possible mechanism of the defects can be attributed to the difference of periodicity in the motion of the different electrons of a same atom involved in the interactions or bonds between the atoms.
will be glad if these remarks will be helpful to clarify the question about the dislocations.
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