The TEM is the best technique for the analysis of size of the nanoparticles and has a higher resolution than SEM, which is basically used for the analysis of shape.

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Article Particle size distributions by transmission electron microsc...

The TEM is the best technique for the analysis of size of the nanoparticles and has a higher resolution than SEM, which is basically used for the analysis of shape.

Thank you for your valuable answer 😊

Dear Mr. Suthar, because the scale of these methods is different. SEM is usually used for surface morphology of the samples in form of power, pellet or film. But TEM is useful for studying the internal structure of the samples because of operating at high working potential, so TEM has higher resolution than SEM and agglomerations could be distinguished with this method especially in particles with smaller sizes.

Place your TEM grid in SEM.

You should see the same particles (with the same size, of course).

Difference in size is (most probably) due to difference in specimen preparation. Also you may have particles with a wide distribution on sizes. Then, if you use higher magnifications for TEM, you can see only area with smaller particles, while utilizing too low magnifications for SEM you will see only big particles. Anyway, It looks like you need to acquire a new set of pictures with TEM and SEM.

Dear Deepak Suthar

There is no difference in particle size measured by SEM or TEM.

By having a close look on the requirement of sample preparation, you will come to know that SEM sample is quite big (contains 100 s of nanoparticles) as compare to TEM (which need only few nanoparticles to be first spread on TEM Cu-grid). The difference in size you observed is actually not for the same particle but for different particles from the same sample. It is almost impossible to have all the particles of the same size in one sample. Thus if you pick the same particle and characterized it in both SEM and TEM you will see no difference in their size.

thank you very much for your valuable answer 😊

Beside all mentioned above, SEM measurement depends on an incident angle. While in TEM the electronic beam falls almost vertically on the sample.

Simply, particles exhibited by SEM images are actually agglomerations of small particles exhibited by TEM micrographs.

@ Ahmed A. Aboud

For particles it makes no difference at all (I mean "incident angle")

@ Adel Maher Wahba

And why agglomeration is seen only for SEM, not for TEM?

I don't know from your only question.

What is the size difference of your particles between the TEM and SEM?

do you take images of the same sample with the TEM and SEM, at the same magnification? And which magnification? SEM cannot be competitive with TEM for high magnification/resolution. The particle is blurry (so larger) in SEM while sharp (so small) in TEM. FEG-SEM is a better competitor.

And finally, have your microscopes been calibrated at different magnifications?

Generally the size should be approximately same in both case. The change is due separation of particle, individual and 3d appearance in TEM indicates like. However, in SEM only surface scanned which also includes the effects of agglomerations.

Probably because of lower accuracy in SEM analysis, you notice factions of two, three or ... as a single particle of larger size. So, when you notice microstructure via TEM, you're looking at particles of smaller size.

If you have an example to share will be helpful.

The instrument calibration may solve your problem.

There should not be a difference however, if your particles are not spherical there could be a difference due to the viewing angle. Otherwise insert a standard and check your calibration

agree with Grumsen

Actually not so... There may be a difference in specimen preparation as the particle distribution may not be the same/homogeneous in both cases. And the magnification range plays a major role in size analysis. Please verify and confirm the both magnification ranges.

Correct me if I am wrong, but for a given particle, assuming it is spherical, the interaction volume and edge effects from the secondary electrons emission would ideally make the same spherical particle appear a bit larger than its TEM counterpart image taken from the thickest section.

Generally, there is not any significant difference in size for both cases. A crystallite is a single crystal in powder form. The crystallite size commonly determined by TEM. However, the grain is either a single crystalline or polycrystalline material and is present either in bulk or thin-film form. During the processing, smaller crystallites come closer and grow to become larger due to kinetics. Therefore, in the most likely scenario, the grain may be equal or larger than a crystallite. And, the grain morphology is commonly determined by SEM (but not XRD or TEM). Therefore, Grain (ensemble of some crystallites and sometimes consists of a single crystalline material) => Crystallite (is the smallest and can be mono- or poly-crystalline).

In a TEM, a nearly parallel beam of electrons travels through a thin specimen, and the resulting image is magnified electron-optically by a series of electromagnetic lenses, the main one of which is the objective lens. That why Particles appear ∼3% larger in the SEM than in the TEM microscope.

Dear Gunel T. Imanova , you have come to astonishing conclusion. 3% because of objective lens!

In a Transmission Electron Microscope (TEM), the electron beam transmitted through the specimen. When it emerges from the specimen, the electron beam carries information about the structure of the specimen that is magnified by the objective lens system of the microscope. However, because the SEM image relies on surface processes rather than transmission, it is able to image bulk samples up to many centimeters in size and (depending on instrument design and settings).

Hum...

The question is very interesting and popular with 500 reads since June.

But we have not yet deciphered about the reason of this size difference because we still don't know the image acquisition setup with TEM and SEM.

Somehow i am agree with Gunel T. Imanova and Kamlesh Paswan . But due to interesting question i am not satisfied till now.

Thanks for this interesting question, in the SEM and TEM instruments, the desired materials are illuminated with high energy electron beams. In a SEM instrument, the beam is scanned over the sample, while in a TEM instrument, the beam passes through the sample. For this reason, a SEM image shows surface morphology and surface characteristics of the samples in form of powder or film, while a TEM image displays internal structure and real particle sizes because of operating at high working potential. The origin of the differences in the particles sizes obtained by SEM and TEM images can be understood from the step of sample supplying for these analyses. For an SEM analysis of powdered materials, some powders are usually utilized. The powder is stuck onto a SEM stub and it is coated by Au or other conductors for nonconductive materials. In the case of a TEM analysis, the desired material is usually suspended in a solvent by a high power ultrasonic instrument to spread the sample well. Then, the suspension put onto a TEM grid and let the solution air dry to obtain a thinly sliced sample. Therefore, the images obtained from TEM analysis has higher resolution and the agglomerations could be distinguished with this instrument, while in a SEM image, the agglomerated particles are usually observed with larger sizes. Hence, TEM analysis is the best technique to obtain the real sizes of materials in comparison with SEM analysis, which is difficult to study real particle sizes.

In the enclosed example, we fabricated TiO2/carbon dots nanocomposites by using commercial TiO2 P25 (from Degussa with the average size of nearly 25 nm) to deposit various amounts of C‑Dots over its surface. As clearly seen in Fig. 2a, the nearly spherical particles have agglomerated and the boundaries are evidently observed. During the sample supplying for the TEM analysis, the operator sonicated the sample in a solvent to spread over the grid. That is why, the real particle sizes are observed in Figs. 2(b, c).

Regards

Aziz Habibi-Yangjeh

The enclosed example is here.