Whether you see any lattice fringes at all, lattice fringes in one direction only or fringes along all directions (zone axis) depends on whether you satisfy Bragg's Law locally, i.e. on the orientation of the crystal with respect to the electron beam (viewing direction). The yellow marked grains seem close to major zone axes, while the red marked ones are tilted both towards the beam and towards each other. So, yes, they are all different grains. Because grains can partially overlap in 3D along the viewing direction and the sample thickness can vary locally, a direct interpretation in terms of grain boundaries is difficult.

Try to identify which phases and which lattice spacings could explain the measured data, taking into account you probably did not work at perfect eucentric height, zero defocus and did not calibrate the magnification using external standards, so errors will be typically up to ± a few %, depending on TEM type and quality of service technicians.

A good textbook I recommend is the one on HREM by the late John CH Spence.

Jason

The analysis of TEM photos of the periodic structures can be summarized as a harmonic analysis and a diffraction pattern can be used to determine lattice plane spacings using a Fourier transform. In TEM, a very thin specimen is irradiated by the electron beam, and to understand the imaging modes, it is necessary to understand the imaging system of TEM and to obtain high-resolution images containing lattice fringes. The interference of the scattered and the unscattered beam is generally used, and the spacings between the lattice fringes can be deduced. From the images you have given, the bright stripes are called lattice fringes, and they can appear in one or more directions. Also, if the specimen is very thin, these fringes can be said as the projection of tunnels between columns of atoms and the dark lines represent the atoms themselves. You must remember that when the specimen gets thicker, then a phase shift could occur, and if this happens, then the dark and bright fringes are interchanged.

Also, look the chaps -3 and 27 of the book- Transmission Electron Microscopy by CB Williams and CB Carter which would be helpful in understanding lattice fringes and phase change.

Dr. K

Jasson

TEM of the nanocrystalline thin film is like fingerprinting. It is a method to identify nanocrystals based on Fourier transforms of high-resolution TEM images. The primary characteristics of the fringes are the lattice spacing and the angle between intersecting lattice fringes to identify a nanocrystal and to make certain of the identity of the nanocrystal, the phase information in the Fourier transform of the image should be employed. Phase determination requires determining the origin of a unit cell in the crystal.

Note, try to read the book put out by Northwestern University "Practical Electron Microscopy and Database. The book gives very detailed information on lattice fringes and is very helpful in TEM image analysis.

Dr. K

Dear sir

(A) If you are sure that the sample consists of grains, then the yellow area is the area where the grains intersect

(B) It seems like "yellow" grain is oriented near zone axis, while "red" grain is oriented near double beam conditions (so that you can "see" only one set of planes). The interplanar spacing in "red" region is nearly equal to right interplanar spacing in "yellow" region

If you want to perform FFT analysis you can use ImageJ (or FiJi) or Gatan DigitalMicrograph with free license