Grain size measurement by XRD is not an accurate determination of particle size because the formula used is assumed as there is no strain at all (Schrer fromula). For accurate particle size measurement use TEM.

XRD sometimes gives ambigious data, plz check it by TEM

The most common problem on using XRD for particle size calculation is that the Scherrer equation uses the peak position and the peak FWHM. The FWHM of a diffraction peak can be affected by the particle size but also from the crystallinity of the materials. So during particle size calculations using Scherrer equation, samples containing particles with the same size but different cristallinity degrees can result in different particle sizes calculated by XRD.

All particle size measuring techniques have their advantages and drawbacks. By TEM for example there can be problems with contrast and sampling. Therefore I always do the measurments using two or more techniques knowing well the limitations of each one.

SAXS is also one of the better techniques to know the particle size distribution. it has advantages over XRD and TEM also i guess..

Can somebody please explain me in detail in calculating the grain size by UV-Visible technique?. Thanks in advance!!!

What kind of nanoparticles? Depending on the material, the models are quite different each other

As the collegue above said the models for particle size calculation from UVvis data can differ from compound to compound.

Infact, Grain size calculation theory takes into account the magnitude of the wavelengths of Xrays & UVis rays.

The size has tio be different other wise we would have also designed theory for IRwaves and Microwaves for grain size calculations. Only Xrays and it's modified techniques SAXS etc,. can provide accurate values for grain sizes. I am talking from the theoretical point of view.

Grain size measurement by XRD is not an accurate determination of particle size because the formula used is assumed as there is no strain at all (Schrer fromula). For accurate particle size measurement use TEM.

Either you may first calculate the strain in the sample using Hall-Williamson formula. It may give you an accurate particle size determination verified by TEM.

Because one of them or both are not suitable !!!

XRD have a lot of limitation in determining the particle size. For example in polycrystalline samples it will give the size of single grain. But more number of crystals may aggregate which can be clearly observable by TEM or HRTEM which is more better method. Moreover your calculation method , Wavelength taken etc are also important when calculating the particle size by your method.

As many of the scientists above mentioned, XRD measurements (Scherer Formula) can only give you an estimation of particle size. UV-VIS data can be used to do an estimation of the mean grain size too, but it's too difficult because you must be very careful about the model to be used. I have to agree that TEM measurements are the most common and safe way to measure the size of the nanoparticles!

TEM and FESEM are more accurate method to determine the particle size, XRD method exactly give crystallite size not particle size, in most of the cases crystallite size is differe from particle size, to many parameters should be consider for determining the accurate crystallite size by XRD mathod, thanks to Mr Rodolfo Ramos-González for giving ref to determine the grain size by uv visible

Renu Hada has right !

Thanks Prof. R. R. Gonzalez! and also thanks to Prof. Renu for his/ her comment!

thank you Dr. Rajendra Khairnar , Dr. VIPIN KUMA, Dr. RConstantin Gheorghies , Dr.Renu Hada Dr.Rodolfo Ramos-González, Dr.Gregory M. Matenoglou and Dr.Abhilash Karuthedath,Parameswaran

Dear Mr. Rodolfo Ramos could you sent this reference to [email protected] because i can not find it

please Dr Renu Hada can you show us the different between the grain size and crystallite size?

Dear Dr. Rodolfo Ramos could you sent this reference to me at [email protected]. I am unable to find it.

TEM is one of the best methods, but you have to be careful and examine several samples and several parts of the sample grid. We use field-flow fratiocination, which is an elution technique and gives size distribution of nanoparticles. see the following: Aggregation of Fullerol C60(OH)24 Nanoparticles as Revealed Using Flow Field-Flow Fractionation and Atomic Force Microscopy-(http://pubs.acs.org/doi/abs/10.1021/la102942b) and Detection, separation, and quantification of unlabeled silica nanoparticles in biological media using sedimentation field-flow fractionation-

(http://www.springerlink.com/content/r7118p2nt34424.).

You can contact me with specifications of your sample and I will see if it is possible to run it on our instrument for collaboration.

Have you ever tried with SAXS? I think its the best method as you gonna get the average particle size and most probable size with maximum accuracy and in a broad range of wave vector

Dear S. Pati , S Assemi thank you very much i will try, may be i examine by the TEM but we did not have SAXS

Best Regards

Mohammed

Mohammed you are welcome. If you are going to use TEM try to suspend your particles in deionized water otherwise the dried salt/surfactant can interfere with the image.

Thank you to all of you