Dear all,
I have a prepared a material which belongs to the orthorhombic system (confirmed by XRD). I want to index the single crystalline data (obtained from SAED) of my material to orthorhombic system. Please suggest some idea...
Dear Mr. Natarajan Karikalan,
To understand to SAED pattern, you have to follow these three steps:
1) You have to understand the zone axis which has been considered during acquisition of corresponding SAED pattern.
2) Then with respect to (000) spot, you have to measure absolute value of angle among different diffraction spots.
3) Similarly, you have to measure the ratio of the distance among the different diffraction spots with respect to (000) spot.
Indeed you have to perform above three steps simultaneously and you will come to know the details of the crystallography of your specimen.
Hopefully, my answer will be useful for you.
Best wishes,
Anjan
Your SAED pattern represents a lattice plane in reciprocal lattice and contains a certain number of hkl which belong to the lattice plane [uvw]* , i.e. the lattice vector [uvw] is the normal vector to this plane. All hkl, i.e. reciprocal lattice vectors, are perpendicular to [uvw]. Crystallographically this means that uh+vk+wl=0.
The length of the lattice vectors represent the inverse value of dhkl which is linked via Braggs law with your X-ray powder diffractogram. From there you know which lattice parameters exists and you can calculate all lattice plane distances. If you now draw circles around 000 (center of your SAED pattern) considering the camera length you should be able to index respective or possibly all points available in your pattern. To simply this procedure usually SAED patterns show often a symmetry so that one can already estimate the type of [uvw]. On the other hand, if your spot pattern displays many points with short distances, hkl as well as uvw cannot have high indexes.
I am sure that you can find also very nice software which already do this automatically. I would recommend you Gu, Xinfu (cf. link).
https://www.researchgate.net/profile/Xinfu_Gu2
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