I heard using XRD it is possible to measure dislocations density or observe them using TEM. I will appreciate if some one explain me how I can measure dislocation density?
I also heard that density of a material can be related to dislocation density, but as I measured the density it was not that much precise to be used in this concept.
Many thanks,
Hello,
XRD and TEM both can be used for dislocation density measurements in the material.
Read the document into the link: http://www.dtic.mil/dtic/tr/fulltext/u2/690901.pdf
Dear Ahmad,
Check the methods in these papers out:
Article The Deviation from Matthiessen's Rule and Electrical Disloca...
Article Dislocation density measurement by electron channeling contr...
Article Investigation of misfit dislocations in α-Fe2O3/α-Al2O3 inte...
Also check the document "Quantitative measurement of dislocation density of low carbon steel wire rods and wires" in my profile. The dislocation density was measured using TEM.
If I remember well, dislocations are kind of structure elements. If so, the structure elements volume anyone can measure using simple (or not simple) image processing software such as ImageJ. If you got picture, mark only dislocations, remove background and count how many you got on several pictures. How to use ImageJ is here: https://www.youtube.com/watch?v=js9ECPuoOwA and it looks not so complicated.
XRD and TEM both can be used for dislocation density measurements in the material, I have used TEM to measure it, however it is a cumbersome technique. Along with the above mentioned techniques Raman spectroscopy can also be used to measure it.
Are you sure density of a material is related to dislocation density? Density is a material property, but dislocation is line defect not volume.
Hello,
XRD and TEM both can be used for dislocation density measurements in the material.
Read the document into the link: http://www.dtic.mil/dtic/tr/fulltext/u2/690901.pdf
In TEM, Weak-beam Dark-field image can be used to estimate the localized density of dislocation in the range of 108cm-2 to 1010cm-2, if the density is relatively uniform in the film.
It depends on the material you are studying and the likely dislocation density. For semiconductor materials with a low dislocation density one can use chemical etchants and use optical microscopy to count the etch pits. At higher densities one can use SEM cathodoluminescence to count dark spots resulting from recombination of carriers at the defects or electron channeling contrast. At higher densities, plan view TEM is probably best.
Dear all,
As I see many answers are according to 'how to obtain picture' and I feel lost in all above. That is why I got answer:
- @Malur Srinivasan it means that picture taken with TEM gives value, such as 0,7 disslocation/10nm^3 ???
- @Ram Krishna XRD will give you value?
- @Marcin Nawrocki: 'High Resolution X-Ray Diffraction with triple-axis geometry' and other mathematical transformation? If so, what software you using?
- @Jialiang Huang, Weak-beam Dark-field (?) will give image, but how to measure dislocation density?
- @Andrew G Norman: SEM cathodoluminescence will give picture, TEM - the same. So how to measure dislocation density?
It is possible to measure density in volume or only on surface because dislocation got only 2 dimensions?
Marcin Nawrocki, thanks a lot for clarification! Looking at answers I had feeling that missed some of important (and basic) knowledge according to structure characterization.
@Ram Krishna: http://aluminium.matter.org.uk/content/html/eng/default.asp?catid=98&pageid=-1065050486
For materials that processed like deformed, theoreticaly it can be used.
within the XRD analysis, several peaks will be appeared, which peak should be selected to compare the FWHM values? for Mg alloy, I saw the expected trend in the first peak (2Theta=32.2o). As it can be seen in the attached file, the extruded sample has a more broaded peak comparing to Pressed sample (extruded followed by press).
I also wanted to ask if texture change will not affect the peaks width values?
EBSD can be used to determine Geometrically Necessary Dislocation. It's possible to generate GND map by using Mtex (matlab texture toolbox) or ATOM software base on EBSD data. In case of Mtex below demo can help you.
https://mtex-toolbox.github.io/files/doc/GND_demo.html
Florina Violeta Anghelina please tell me how can i calculate dislocation density
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction