Recently I synthesised FAPbBr3 NCs. I took TEM of that material. At 100 nm it is showing really good homogeneously distributed NCs. But operators were unable to find any lattice fringes in my material. Is it possible that for some material we will not get any lattice fringes according to the charecteristics of the material?
Dear Deblina Das, Yes, it is possible not to observe lattice fringes in TEM images even with homogeneously distributed nanocrystals (NCs) at 100nm. The presence of lattice fringes can depend on various factors, including the material's characteristics, crystal structure, defects, and imaging conditions. In some cases, specific materials may not exhibit clear lattice fringes due to their unique properties.
Alvena Shahid ma'am thank you so much for your time and the answer.I really appreciate it. Thank you so much again.
Hello,
lattice fringes are a diffraction phenomenon.
Your sample (NC) must be (i)crystalline and (ii) in a proper position (BRAGG position).
The spacing of the fringes will be in the order of the lattice spacing (i.e in the Angstroem range).
You need very high magnification (HRTEM mode) to see it (see Fig. 5 here:
Article Removal of heavy metals (Co, Cr, and Zn) during calcium–alum...
)You'll need images of much higher magnification (single crystallite or less) as the images shown.
Stefan Baunack Thank you so much for your advise professor. I took images at 10 nm also but there is no fringes. Do you think we need to take pictures in 5nm scale to see the fringes? I am attaching image at 10 nm magnification also.
Dear Deblina Das, the technical quality of your your images is not sufficient.
The TEM must be set to HR mode and carefully adjusted.
In the paper I linked the image width (Fig 5d) is let say 20 nm @ 700 pixels (in the figure): 28 pm/pixel.
Your image TEM10nm.jpg is 50 nm wide! In your image you have ca. 170 pm/pixel.
Your goal is to measure distances of some Angstroem (=100 pm).
(i) The magnification (or image width) is important (image width < 20 nm).
(ii) The number of pixels is important (Nowadays a CCD camera should have 1024 pixels or more)
(iii) The images should be recorded and shown in uncompressed format (TIF or PNG). JPG is not recommended (JPEG, quality: 90, subsampling ON (2x2)) because it can introduce artifacts.
Stefan Baunack Thank you so much professor for the explanation. I will keep this in mind next time.
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