you can use the lineprofile Tool both for HR images and diffraction patterns. Use as many diff spots  or atom columns as possible. However XRD is much more precise

Hello,

both line profile and FFT are very convenient, but still you should remember that on HRTEM analysis you are analyzing only a very small area and if your sample is powder one you should check also electron diffraction for lower magnifications. This should assure you that you are investigating real structure and not some artifacts. 

Normally I'm using FFT, measuring two opposite reflexes and I'm calculating spacing from d=2/L equation. This should give you spacing in nm with minimal error. It's always safe to check what uncertainty give moving L line with one pixel, especially when you have two materials with similar lattice spacing. Afterwards, I'm double checking the result with line profile which is more direct way of measuring, but less precise...

Hi, calibrate your diffraction pattern und measure the distance as shown in the attached screanshots (you can also use ImageJ):

Thank you All, i already calibrated my diffraction patterns  ( in attached screenshots). that mean my lattice is : 1.5-0.5/4 = 0.25 nm?

More or less, try to focus a little bit more precisely, and when you are in underfocus (like on this picture) you have black atoms, so it's better to measure not from peak to peak, but in-betweens :) peak is a greater intensity, which in this case is a white interference halo around atoms...

Oh so, you ask for HRTEM and not for electron diffraction!? I think the quality is nice because the specimen is not so easy, but you can use for evaluating the FFT and then you work in the reciprocal space with the unit 1/nm:

If you are dealing with HRTEM micrographs and you intend to do FFT, please be careful when identifying directions and lattice constants, because of possible structure overlay. This can make Moire pattern to appear and such effect can be very confusing...

Hi Volker Klemm,

How to interpret lattice parameters from this image as it is having no. of closed peaks and and of variable heights.