Here the HRTEM image is enclosed in which at two places a kind overlapping is observed.
Can we consider it moire fringe? And if it is what may be reason for occurrence.
you can use Gatan DigitalMicrograph, and select the area you want by using FFT then convert to a layers so then you can obviously measured the d spacing you select.
Some time ago we have found a peculiar example of the moire fringes, which in a number of papers was misinterpreted as a new structure, have a look:
https://www.researchgate.net/publication/12745288_Origin_of_Threefold_Periodicity_in_High-Resolution_Transmission_Electron_Microscopy_Images_of_Thin_Film_Cubic_SiC?fulltextDialog=true&ev=prf_pub_xaddfulltext
Article Origin of Threefold Periodicity in High-Resolution Transmiss...
your image shows a number of lattice fringes and actually two examples of moire fringes (the coarser fringes) that are both due to a superposition of lattice fringes from different cystals. They can be explained by multiple diffraction. With g1=1/d1 and g2=1/d2 the moire-fringe spacing in real-space is 1/(g1+g2)=(d1*d2)/(d1+d2) where you should use the corresponding vectors in the above formula.
Dear Thomas
off course superposition of fringes are there. how can i find corresponding vectors?
measure the spacings d1 and d2 of the superimposed lattice fringes and the angle theta between them. Then the moire spacing is d1*d2*cos theta/ square root [(d1^2+d2^+2*d1*d2*cos theta)]. Thomas
Dear colleagues, I'd like to bring to your kind attention a more complicated problem, namely that of curved fringes which seem to be of moire type (please, see the attached HRTEM images). I found on the web some indications on that the curved moire are due to the mechanical stress between the two superposed crystals, but not found a text describing in detail the procedure of treating and measuring the characteristic parameters in this situation. Could you, please, help me about:
1. how to settle for sure that my curved (seemingly) moire fringes are actually this kind of fringes;
2. the procedure of measuring the parameters involved in the image formation of my curved moire fringes;
3. where could I find a text, on web, hopefully freely accessible, to learn about the stress determination on the ground of similar HRTEM images to that posted herewith. I am holding more similar HRTEM images.
Thank you.
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