My suggestion is not to forget the basics.. always:
Powder diffraction: the term "powder" indicates a specimen that contains a large number of monocrystalline domains covering most orientations and diffracting incoherently. To meet those requirements with a finite beam, this means that the grains should be sufficiently small... So, yes X-ray diffraction can work on bulk materials.
TEM vs SEM vs XRD.. why people NEVER consider how much of the specimen they sample? With microscopy you are sensitive to the single grain but you would never survey enough to represent statistically your specimen! With diffraction you survey enough grains to guarantee that your sampling is representative for the specimen, but you can't identify the singular grain unless it has a large enough volume.
So the answer to the original question largely depends on what's the aim of the microstructure analysis and what type of specimen you have/what the requirements are (very small, film, crystalline, nondestructive measurement) .
For instance, if you want to measure the dislocation density in a heavily milled powder, diffraction is the only viable alternative (provided you use the proper tools), If you need to get information on the grain size of n ingot you would probably use the light microscope. If you need to find out what carbides/precipitates you have in an alloy you'd probably go for TEM...
...so the more general the question, the broader the answer!
PS for those who talked about amorphous and diffraction.. just notice that if you take a wide enough pattern, do some polishing and a Fourier transform you obtain the Pair Distribution Function... You can extract information on the structure and partly on the microstructure from it (if you are lucky)!
SEM: Microstructural aspects near to surface (up to few submicrons)
TEM: Detailed analyses including other defects i.e. dislocations,stacking faults etc.
Diffraction of different modes (e.g. DF image BF image ) for different phases, defects etc.
X-Ray: Only diffraction
X-Ray studies will be help to determine the crystalline amorphous nature.
XRD: studies if the sample has a crystalline or amorphous nature. If the sample is crystalline you can study its microstructure as well as its crystal imperfections.
SEM: study the surface morphology and microstructural aspects near to surface only.
TEM: study the details of the sample and its crystal imperfections.
I have already posted this link but the information there can help you to understand the aim of each technique
http://www.ammrf.org.au/myscope/
All the three techniques are used for structural studies but each one has its advantages and limitations. X- ray diffraction can be used on powdered specimen, bulk material as well as in thin film form.Fraction of crystallinity of different phases for example amorphous and crystalline phase, can be assessed by X - ray diffraction. TEM can also be used for structure determination by electron diffraction but TEM can be done only in films which are transparent to electrons.Thickness should be less than 100nm.However, there are some advantages of TEM as it can give informations about defects in crystalline films. SEM is used for the surface morphology and particle size determination
SEM: this technique will give you information about the structure of the surface of the material you are studying. This is because the image that you see on the screen is formed from the electrons that 'rebound' (let me use this non scientific word) on the surface of the material you are studying.
TEM: in this case you will also have information about the structure of your material. In this case, you receive information about that structure from the electrons that pass through your sample, so the image in the screen is formed from the electrons that pass through the sample.
X-ray: while SEM and TEM give you information about the structure of the material, an X-ray analysis gives information about the crystallographic structure, so you can determine if the material is amorphous or not, If it is not, you can determine its microstructure.
While in both SEM and TEM you can study a bulk material, you need to use powder to perform an X-ray analysis.
Hope this helps!
My suggestion is not to forget the basics.. always:
Powder diffraction: the term "powder" indicates a specimen that contains a large number of monocrystalline domains covering most orientations and diffracting incoherently. To meet those requirements with a finite beam, this means that the grains should be sufficiently small... So, yes X-ray diffraction can work on bulk materials.
TEM vs SEM vs XRD.. why people NEVER consider how much of the specimen they sample? With microscopy you are sensitive to the single grain but you would never survey enough to represent statistically your specimen! With diffraction you survey enough grains to guarantee that your sampling is representative for the specimen, but you can't identify the singular grain unless it has a large enough volume.
So the answer to the original question largely depends on what's the aim of the microstructure analysis and what type of specimen you have/what the requirements are (very small, film, crystalline, nondestructive measurement) .
For instance, if you want to measure the dislocation density in a heavily milled powder, diffraction is the only viable alternative (provided you use the proper tools), If you need to get information on the grain size of n ingot you would probably use the light microscope. If you need to find out what carbides/precipitates you have in an alloy you'd probably go for TEM...
...so the more general the question, the broader the answer!
PS for those who talked about amorphous and diffraction.. just notice that if you take a wide enough pattern, do some polishing and a Fourier transform you obtain the Pair Distribution Function... You can extract information on the structure and partly on the microstructure from it (if you are lucky)!
I just want to remind about couple things about "X-rays":
1. Not always powder diffraction is best for XRD. M
Bulk metallic (and other multigrained) specimens can be polished and rotated in their holder - to imitate conditions of powder diffraction. Also balk specimens are used to study texture of specimens.
2. Also "X-ray" study may mean EDS (WDS) - examination of atomic composition of specimen.
I believe this presentation should help you with a basic understanding of SEM and TEM.
http://www.wsi.tum.de/Portals/0/Media/Lectures/20082/cb899e9b-2deb-4cb9-bfd5-344821c84fe9/electron_microscopy_forster.pdf
Good luck!
That's a very broad question. It really depends on what aspects of micro-structure you are interested and the type of material you are studying. Could you be more specific. I notice most posts refer only to diffraction with x-rays. There are many many other techniques: Imagining (tomography, topography, holography, CDI, 3DXRD, DCT...), spectroscopic techniques (Fluorescence, XAFS, XANES...), small angle scattering, reflectivity (for multilayers or thin films), magnetic scatteriing,.....
TEM and SEM can be used for microstructural examination. Whereas SEM is helpful to study surface features and is best utilized for fracture surface studies to distinguish between ductile and brittle fracture, TEM is more suited for in-depth analysis of precipitates, dislocations, imperfections inside the material. Bulk sample can be used for SEM studies but a thin film of material is required for TEM study as electron beam has to pass through the material to reveal internal structure.
XRD is best suited for study of nature of phases/ microstructure and their crystal structure.
Normal X-ray diffraction method examine large area and collect the statistical information over the measured area, TEM and SEM usually collect local information, TEM needs specimen preparation to reduce the thickness below 100nm, TEM investigates inside while SEM studies the surface.
I agree with Lawrence here its a broad question and really depends on what you want to obtain: the details. The fundamental difference is of course photons versus electrons and their different interaction and consequently different penetration depth (depends on energy of course). Diffraction information can be obtained in both electron microscopies TEM and with backscattered electrons in the SEM. In general X-Ray Lab sources have medium intensity and illuminate quite large areas, average over the sample, and so are not so amenable to microscopy investigations. This is not the case with Synchrotron sources which can have spot sizes of micron and below and high intensity. Both transmission and scanning methods are available. In addition these can be combined with spectroscopic techniques e.g. fluorescence (also available in electron microscopies) and also XANES (chemical state information) by scanning the X-Ray energy (similar information is obtainable by energy loss in the TEM).
However as above it really depends on what the questions are and of course the instruments available.
That's too bad since Vindor's comments were obvious at best and wrong at worst. Why would you post just to say you agree with someone anyway? Either you have something to add to the discussion or you don't (perhaps because someone else has already posted it, in which case just move on.
Let me breakdown what is wrong with Vindor's post:
"TEM and SEM can be used for microstructural examination. Whereas SEM is helpful to study surface features and is best utilized for fracture surface studies to distinguish between ductile and brittle fracture,
SEM is best utilized to determine between ductile and brittle fracture? I think what he means is: That's that only thing I've used it for.
TEM is more suited for in-depth analysis of precipitates, dislocations, imperfections inside the material.
I have no idea what is meant by in-depth, but TEM is suited for a whole lot more than that, and is not even best suited for precipitates. Imperfections? That's a pretty vague.
Bulk sample can be used for SEM studies but a thin film of material is required for TEM study as electron beam has to pass through the material to reveal internal structure.
I can't argue with this.
XRD is best suited for study of nature of phases/ microstructure and their crystal structure.
Really?
Please people, if you don't have a firm grasp of the subject matter of the question please refrain from answering, and even more please refrain from repeating previous wrong or correct answers, and please please don't just post I agree with what he said. It does not further the discussion and is basically spam.
If you are interested in particle size, then both will give required information. SEM concentrates more on the surface of the sample with some depth by means of scattering whereas TEM works on transmission mode. Accuracy can be made high in the case of TEM and it is very useful in understanding the defects. XRD gives data in reciprocal space. Electron diffraction is possible with SEM and TEM
Usage of XRD, SEM and TEM depends mainly on nature of the information that we are interested.
Read the question! It says X-ray not XRD. Read my post .... how many of the x-ray methods that I listed give you information about reciprocal space?
Browsing through the answers a few minor details which I would add: if we speak about different probes one should perhaps include neutrons, even it is a bit exotic.
Besides the mentioned techniques, issues with field of view, penetration depth etc. I think one of the properties of X-rays is that at least technically it allows for studying a sample in a hierarchical manner, i.e. from macro to micro and perhaps even beyond.
SEM is used for topographical, compositional and morphological characterisation while TEM is used for studying internal structure and of course composition. XRD is used to study nature of phases/ microstructure and their crystal structure..
agree with Palvinder Kaur, SEM give you inlformation about surface features of you sample. It also can give you elemetal composition of your sample surface/bsub surfface when combineed with EDAX (sometimes also termed as EDS). TEM uses the electron beans goes throug hyour sample to form the image, so that it gives information inside your sample, such as composition and phasestructure. TEM has higher resolution than SEM, thus you can use it for analysing finer structure. TEM also provide elecronic diffaction from which you can obtain the crystalline structrure of your sample at the sacle as small as a few nanometres. XRD is only sueful for crystalline materials. From the XRD patterns, you can identify the crystal structure or different phases of crystalline materials in your sample. For example, you can find the deffraction peaks for iron and nickel in your alloy, or you can also use it to identify different crystlline phases in pure matters when they are treate in different conditions.
If Mateo & Larry are in, I'm in in :-)
Here's my "two bit". Hope it furthers the discussion and is not just gratuitous!
In the table below "DARC topography" and "Conventional RC" would fall under XRD methods. The contemporary spatial resolution limit of XRD is 1-5um per Pixel size on the detector. Much more details may be added to the table below. Constructive comments (including criticism) and suggestions would be great. Obviously, I missed AFM! I'll fix the table once I study the input to this content rich discussion thoroughly. Any suggestions or comments to help enhance the table of info below would be deeply appreciated.
Here is a link to the LinkedIn discussion on this matter. Please review and share. This is a fundamental yet important topic to pontificate on, in my opinion :-)
https://www.linkedin.com/groupItem?view=&gid=2683600&item=5963674379723251714&type=member&commentID=discussion%3A5963674379723251714%3Agroup%3A2683600&trk=hb_ntf_COMMENTED_ON_GROUP_DISCUSSION_YOU_CREATED#commentID_discussion%3A5963674379723251714%3Agroup%3A2683600
In the table below:
1. DARC Topography is for 2D XRD Rocking Curve Topography.
2. RC is for conventional XRD rocking curve analyses using a 0D approach.
3. SEM, TEM, RBS, PL etc. you already know.
1. "XRD is only useful for crystalline materials." - The incorrect word is "only". XRD can be used for characterizing the Nanostructure of materials that may be gaseous, liquid, solid, amorphous, nanocrystalline, polycrystalline, monocrystalline, paracrystalline, pseudocrystalline, etc. As long as there is some periodicity/aperiodicity in the matter, it can be sensed by XRD techniques.
2. For some bizarre reason (I know not) the message of the incredible reciprocal space resolution possible with XRD has fallen on "deaf ears" among XRD utilizers. It is obvious a more effective method of propagating this century old good news in the community is needed. The message that Matteo, Larry and many others are sharing is privy to mostly those involved with esoteric XRD such as in the Synchrotron facilities. More applications with conventional XRD systems are needed for these methods to become ubiquitous and "desirable".
Dear colleage Xu,
Energy Dispersive X-ray Analysis (EDX) can be used to investigate the properties and compositions of a broad range of sample types. EDX is used for chemical identification of elements and their concentration.
X-Ray Diffraction (XRD) is used for Phase identification. It is used to identify spatial arrangements of atoms in crystalline phases.
In EDX, electrons knock out electrons from atoms, producing X-rays of characteristic wavelength. These X-Rays are then detected to identify the element from which they were produced. In XRD, X-rays of known wavelength are used to probe the structure of the material, using the lattice as a diffraction grating.
To perform an EDX you need an electron source. For XRD you need an X-ray source.
If you are looking for chemical composition, concentration gradients, or solute segregation, use EDX.
If you are looking for phase distribution, lattice strain fields or stored defect content, use XRD.
hope this helping
Have a very good day
Hi,
Electron microscope follows the same ideas of optical microscope, but uses electrons instead of light;“Lens” here are not the optical materials (like glass), but electrical field.
A Scanning Electron Microscope uses a beam of electrons to scan the surface of an object to create an image detailing the topography and composition of the object’s surface.
A Transmission Electron Microscope is used to magnify objects. It aims a beam of electrons onto the object to form a magnified image called a micrograph.
In SEM an electron beam is focused into a small probe and is rastered across the surface of a specimen.Several interactions with the sample that result in the emission of electrons or photons occur as the electrons penetrate the surface.These emitted particles can be collected with the appropriate detector to yield valuable information about the material.The most immediate result of observation in the scanning electron microscope is that it displays the shape of the sample.The resolution is determined by beam diameter.
In transmission electron microscopy (TEM), a beam of highly focused electrons are directed toward a thinned sample (
Dear Dr. Qihua Xu
Have a nice day and good times
SEM: gives you information about the structure of the surface of the material which you are studying. This is because the image that you see on the screen is formed from the electrons that 'rebound' (let me use this non scientific word) on the surface of the material you are studying.
TEM: in this case you will also have information about the structure of your material. In this case, you receive information about that structure from the electrons that pass through your sample, so the image in the screen is formed from the electrons that pass through the sample.
X-ray: while SEM and TEM give you information about the structure of the material, an X-ray analysis gives information about the crystallographic structure, so you can determine if the material is amorphous or not, If it is not, you can determine its microstructure.
good Luck
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