All of these techniques have been used to report particle sizes. However, it is important to realize what "particle size" it is you want to measure and it is often beneficial to use cross characterization to characterize particle size. Imaging (TEM, SEM, and STEM) often correlate well with primary particle size or crystallite size. The problem with imaging techniques is that it is typically impossible to distinguish between agglomerates and aggregates if your particles are not completely dispersed prior to imaging. It can also be tedious to measure size distributions by imaging. XRD measurements will give you the average primary particle size if you have a nanocrystalline material. Thus, XRD will not provide a size distribution or tell you anything about agglomerates and aggregates. BET and density measurements can also be used to provide a rough approximation of the primary particle size.

Laser scattering or X-ray attenuation with a centrifuging force can be used to determine average particle sizes and particle size distributions. However, the results must be interpreted with caution. If the sample is not dispersed well, you will most likely be measuring an agglomerate size, which will depend on numerous aspects of sample preparation. If you are certain the particles are dispersed well, then you will be measuring the aggregate size. If the particle size matches the primary particle size, then you have a highly dispersed system essentially without aggregation. To use light scattering, you must also make sure that you do not have settling or your results will be skewed. The structure of the agglomerates or aggregates (porous or dense) can also skew results. As such, comparative analyses rather than absolute analyses are recommended. If there is a standard, I think it should be a guide rather than an exact procedure because the sample preparation necessary to properly disperse a sample can vary significantly from sample to sample. Sieving has also been used and will surely correspond to an agglomerate size. Keep in mind that the attractive forces that form agglomerates are greatest in air (for dry powders) than it is for powders dispersed in a fluid and can also vary with the specific fluid that you use and any dispersants that you add. It is useful to be familiar with the concepts of colloidal stability if you are not already, including coagulation and various dispersion mechanisms.

As quoted, sample preparation is an important step in order to get an reliable result. I would suggest the use of two or more techniques and compare their results. This exercise could help in getting a better idea about the particle size.

AFM can also be used for determining the particle size.

Here are some other related discussions:

RG:https://www.researchgate.net/post/Why_is_there_a_difference_in_the_crystalline_size_of_the_nanoparticle_as_measured_from_TEM_image_and_XRD_analysis_of_the_same_sample

LI:http://www.linkedin.com/groupItem?view=&gid=2683600&type=member&item=5878921266752163841&qid=9a9da5a7-ce8f-460e-9059-f931ca40c6e5&trk=groups_most_recent-0-b-ttl&goback=%2Egde_2683600_member_5878921266752163841%2Egmr_2683600

Particle Size Analysis Market - By Technology (Laser Diffraction, Dynamic Light Scattering, Imaging, Coulter Principle, Nanoparticle Tracking Analysis), by Emily Brown, Senior Research Analyst at IBN Group

https://www.linkedin.com/groupAnswers?viewQuestionAndAnswers=&discussionID=5873146218112110596&gid=2683600&goback=%2Egde_2683600_member_5878921266752163841%2Egmr_2683600%2Egde_2683600_member_5878921266752163841%2Egmr_2683600%2Egde_2683600_member_5878921266752163841#commentID_null

"sample preparation is an important step"! What precautions would you propose/recommend for precise results?

Particle size should not be equal to Crystallite size.... From XRD you will estimate the crytallite size not particle size.. because aggregated crystallites forms particle.....DLS/HRTEM is ideal for estimating particle size....

I think the best and simplest way is using SEM for both of micron and nano sized particles...

You are right sir.... However, when the particle size is enormously reduced (< ~10 nano meter) the long range symmetry of the motifs (periodic atomic position) are started to degrade and it is close to amorphous... XRD may not be ideal for that cases... HRTEM is highly favorable for such cases..

Yes, sample preparation is important. The steps I would take would obviously depend on the technique you intend to use, the size of the particles, and the dispersion mechanism that you intend to use (i.e. electrostatic, steric, etc.). It might also be important to understand your particle surfaces since it can have significant consequences on colloidal stability and dispersing.

HRTEM, TEM, SEM have all the same drawback in comparison with XRD, weak statistics and inability to resolve the "diffracting domain size". Practically, most prefer a combination of methods along with "known standards" for calibration.

In my opinion, the conventional practice of "severe deformation" (grinding) for XRD observations should be reassessed and in situ measurements should be promoted along with 2D diffractograms.

XRD using high frequency X-rays and Laser scattering could be used.

I think insead of going for SEM, you can use TEM or DLS to determine particle size.

I usually used two approach: Grain Size by XRD data and that you analyzed using Scherer equation and TEM is usually for calculate crystal size.

Yes Ken! You are correct. It gives an idea of the diffracting domain size with some emperical assumptions for their shape.

SAXS will also give you this size irrespective of the crystallinity of the "particles". It all depends on the periodicity.

first of all, the preparation method is important, because it help to find out the colloidal stability and dispersion. In the range 1nm th 10 nm crystalline size you should approach to HRTEM .

Vikas! "In the range 1nm to 10 nm crystalline size you should approach to HRTEM".

1. How would we define "crystalline size"? Is it the smallest coherently diffracting (scattering) domain size one could detect with the instrument/technique/wavelength and reciprocal space range utilized?

2. In the case of HRTEM, let us understand some of "the preparation" involved. What would be the typical time frame, tools and techniques needed to create such a HRTEM ready sample from the following (for example)? What cost per hour? What resolution?

i. Aluminum, Brass, or Ni foil. 200-500um thick.

https://www.flickr.com/photos/85210325@N04/8707355113/in/set-72157632728981912

ii. LaB6 "standard" powder. Max 90um measured with laser scattering by supplier.

https://www.flickr.com/photos/85210325@N04/7909734896/in/set-72157632724090465

iii. Kevlar fiber or other bulk fiber both conducting and non-conducting.

https://www.flickr.com/photos/85210325@N04/7975835813/in/set-72157632728981912

iv. GaAs, GaSb, SiC, TeO2 or Ge monocrystalline.

https://www.flickr.com/photos/85210325@N04/9430820747/in/set-72157635172219571

It would be awesome to calibrate the real time in situ XRD findings with HRTEM!

https://www.flickr.com/photos/85210325@N04/10659886546/in/set-72157645018820696

Stats @ 07:40hrs EST 6-9-14 10 contributors, 11 followers,

0 / 0 · 18 Answers · 110 Views

I just added 5 more topics to a total of 15. I'll send it for another "Share" spin around the networks and then observe stats.

XRD gives crystallite size not the particle size and not grain size

I agree with Natheer Basheer Mahmood. XRD is not a good method to predict particle size. However, sometime, it is in agreement with FESEM, HRTEM techniques to measure the particle size. It occurs when the particle sizes are homogenous.

In my opionion, 1，2，and 5 are the answers.

I agree with Kenneth: "... it should depend on what the scientific question is that requires analysis of powder particle size."

All these methods can be used depending on the question and samples. It is not to be expected that the same result comes out for all methods.

A not yet discussed technique is the cut and slice with the FIB. It is a very time-consuming process. It probably makes sense suitable for particle sizes from 40 nm to 2 micron. It is favorable that even agglomerates can be investigated and that the particle shape is insignificant (for example if you have plates, rods or Ellipsoids). The exact shape can be calculated by means of 3D-reconstruction. In some cases even a few cuts enough to get an idea of the sample. It is difficult however to make a statistical statement about the size distributions because it is too expensive.

limited of equipment, depending on scientific question, because it is too expensive.... it could be wrong if we used word 'approach'?

Small angle x-ray scattering (SAXS) is a fantastic method for measuring statistical distributions in particle size and shape as well as grain size and shape on length scales from 1 nm to 10 microns. Coherent Diffraction Imaging (CDI) is also a very useful tool. It's amazing how many people think that x-rays cannot tell you anything about particle size when in fact it is one of the most accurate methods.

XRD including SAXS & WAXS will reveal the entire Nano structural make-up of your sample provided we are able to decypher every minutia of the scattered signal without prejudice. I'm not there yet. But one must master Guinier's XRD in Crystals, Imperfect Crystals & Amorphous Bodies, A Classic from the 1950-1960's as a pre-requisite. A must have in your collection. Try EBay!

https://www.flickr.com/photos/85210325@N04/10515372183/in/set-72157645018820696

As Lawrence Margulies says Small angle X-ray scattering in good method for measuring the particle size and shape.

1) When you are able to find Angstrom sized particles and measure them, please invite me to your Nobel prize ceremony or you mental institution, whichever best applies.

2) Call me crazy, but a particle that is micron sized wouldn't seem to warrant being called a nano particle.

3) I think the appropriate answers have been given. I think you are over thinking the question, which is simply what techniques can determine particle sizes that approach the theoretical limit and which are not in the micron range or above (which I hope we can all agree are not nano particles).

Lost you there a bit Larry! Please elaborate. I suspect it is the old culprit semantics. Are you eluding to "particle size of Nano powders", a contradiction in terms perhaps? I should rephrase it perhaps to be unequivocal?

yes particle size. That was the original question, right? I don't see that particle size of nano powders is a contradiction in terms. It makes perfect sense to me.

Arnab! "when the particle size is enormously reduced (< ~10 nano meter) the long range symmetry of the motifs (periodic atomic position) are started to degrade and it is close to amorphous"

XRD may be used to characterize the Nano and Micro structure of materials ranging from crystaline to amorphous to liquids to gases in situ with modern tools and techniques. The resolution capabilities are improving leaps and bounds. Stay open-minded my friend! :-)

This seems as good a place to wrestle it down. I'll be glad to join any other discussions that you initiate. There are other RG discussion about this subject abounding in pontifcation without concensus. Only some agreement. It seems to depend on the field of study and the materials themselves. These are the terms that appear to be of interest: particle, grain, crystallite, diffracting domain, coherently diffracting domain.

Let's elevate this discussion to the next level, if you please.

I'd love to hear any definition of particle (in a materials sense, and not a particle physics sense) which would include angstrom size as a possibility.

Really? Are you really playing this game? Im not. 80 angstroms? I give up you win.

Ken & Larry! The sizes you folks are talking about are mind expanding. Obviously, both your experience and knowledge will help all of us open our minds to the "extreme sizes" that one could encounter in "real life". I'm aware of some very interesting Nano structural morphologies present in meteor remains. The folks at both the Smithsonian Institute and Argonne National Lab (APS) are actively studying such materials. We appreciate both your perspectives. Thanks for sharing!

Eventually, a mutually collaborative effort between Electron Microscopists and XRD Microscopists will crack the Nano structural enigma, in my opinion.

From my reading of several posts on RG regarding this subject, here are some of my current perspectives:

1. Particle: Could be crystalline, amorphous or a combination. Could also be an agglomerate of many constituents and morphologies?

2. Grain: Generally used by metallurgists and other materials scientists to denote materials separated by distinct "grain boundaries" (incoherent). Individual grains may contain sub-grain boundaries. This term is also used by others sometimes synonymously with "particle". "Grain boundary" in itself need to be defined to distinguish from sub-grain boundaries. Probably based on the net angular tilt somehow?

3. Coherently diffracting domain size: This would depend on the resolution of the observation technique. It would depend on the how low a small angle sub-grain boundary that one could resolve. Generally implies a 3D region in the material that is crystallographically "coherent" (identical or indistinguishable).

Help us try to put this Genie back in the bottle! Still open-minded!

Here is the other discussion on this matter:

https://www.researchgate.net/post/What_is_the_difference_between_crystallite_size_grain_size_and_particle_size?cp=re65_x_p2&ch=reg&loginT=jz5bVhks6TUIj27QcKvNjg26GxMOB1xTcWFlu4rx3I0%2A&pli=1#view=53a82db4d685cc002a8b45c9

I'd choose the TEM characterizations, although some nanoparticles are hard to be identified if calculating not precisely. Other methods are uncorrect more or less.

TEM by using Image J software & Powder X-ray by using Modified Scherer Equation.

Respected Kenneth M Towe

In my view by taking average dimension by TEM analysis.

With Best Regards

Interesting discussion!

Interesting discussion!

for 3D particles, size distribution could be measured using PSA.

But how about for 2D flakes like graphene oxide, should we use TEM?

Microscopy

Sieving

Sedimentation techniques

Optical and electrical sensing zone method

Laser light scattering techniques

Surface area measurement techniques

this link is useful

https://www.tcd.ie/CMA/misc/particle_size.pdf

regards

I want to distinguish between

A CRYSTALLITE is a single crystal in POWDER form.

and A GRAIN is a single crystal within a BULK/THIN FILM form.

SE micrographs have been used for starting powders, we often initially report the particle size, because we can't accurately determine whether the particle is one crystal or composed of many compacted single crystals. Then after XRD or TEM analysis we can usually say whether each particle is an agglomerate composed of smaller crystallites or whether each particle is a single crystallite.

Mainly by using TEM micrographs u can determine the particle size. But in some cases I see that by using XRD technique u can calculate the particle size { graphen oxide}