I have an intensity and 2θ data (10-80 degree) for n-type SiC which is having hexagonal structure. The sin2 θ values for first and second peaks are 0.098 and 0.422. I’m unable to see the standard values of a & c with calculations.
If I proceed with the assumption of hk0 (B.D. Cullity: Elements of X-Ray Diffraction) then I’m getting indices as 1000 and 2000. However, the orientation of the sample is .
Instead, when I went with 00l assumption which is not mentioned in that textbook, don’t know if my assumption is correct, then I’ll be getting indices as 0001 and 0002, but in this case, the obtained a and c values are not as that of standard values. (λ=1.54184 Å)
FYI: sin2θ = A(h2+hk+k2 ) + Cl2,
where A=λ2/(3a2 ) and C=λ2/(4c2)
If you have only the information from a 00l reflection you can only measure this. It is the same if you are looking on the front of a house and you need to determine the depth. It is impossible. The lattice parameter a only affects reflexes h00, hk0, hll, hhl and hkl.
As N. Dragoe pointed out, you can use free available programs which fit at least the lattice parameter c. And your last calculations assume for A that you would have a 110, and for C a 002 interference? Why? You only have 00l so that A is impossible to determine...?
You could go to a diffractometer which enables to measure texture. In your case preferably an instrument which docouples omega and theta, i.e., you could move your detector to an approximate 2theta position. The sample will be rotated by omega so that this plane is in reflection condition. Since now the normal can be still out of the plane given by the X-ray beam and the direction of the detector you need to rotate your sample around its normal (like for texture measurements). Then you should see intensity at a position phi (rotation angle). Since all angles (2theta, omega and also phi) won't be the optimum, you have to refine them step by step using the maximum intensity as criterion, i.e., you can process rocking curves or simply do the same as before but decreasing the step width. A 2D detector would make everything much easier of course.
If you have only the information from a 00l reflection you can only measure this. It is the same if you are looking on the front of a house and you need to determine the depth. It is impossible. The lattice parameter a only affects reflexes h00, hk0, hll, hhl and hkl.
As N. Dragoe pointed out, you can use free available programs which fit at least the lattice parameter c. And your last calculations assume for A that you would have a 110, and for C a 002 interference? Why? You only have 00l so that A is impossible to determine...?
You could go to a diffractometer which enables to measure texture. In your case preferably an instrument which docouples omega and theta, i.e., you could move your detector to an approximate 2theta position. The sample will be rotated by omega so that this plane is in reflection condition. Since now the normal can be still out of the plane given by the X-ray beam and the direction of the detector you need to rotate your sample around its normal (like for texture measurements). Then you should see intensity at a position phi (rotation angle). Since all angles (2theta, omega and also phi) won't be the optimum, you have to refine them step by step using the maximum intensity as criterion, i.e., you can process rocking curves or simply do the same as before but decreasing the step width. A 2D detector would make everything much easier of course.
Thanks Gert and Nita.
Yes, if I assume 00l, then it is impossible to determine A.
Is there any other way to calculate a and c manually for 00l reflections?
I also would like to know, if the described experiment is requisite to perform? Thanks.
Hi Nita,
Thanks.
Yes, I agree. As my sample (SiC) is having 000L orientation, and having only two peaks as mentioned in details but I'm not getting the mechanism involved in finding a & c. And how to proceed to calculate those parameters in this case. I also tried your software unfortunately unable to install it in my pc.
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