[bucky_bowl]

Hi, I'm a UG student and have to sort some XRD data for an unknown zeolite for an assignment;

I got the raw 2-Theta data and have copied it into excel, done the necessary conversions to theta, radians, and calculated sin^2 theta, however, now i have got to the ratios but I am very confused by them as they follow none of the patterns we have been taught (only Centred and Centred lattice) so they should roughly represent 1.00 : 1.333 : 2.666 : 3.666 : 4.00 etc for a Centred lattice or contain a seven for an Centered lattice (1 : 2 : 3 : 4 : 5 : 6 : 7 : .  The results I have got are below:

1.00
2.682449273
3.69892407
5.41875245
6.419104221
8.177436474
9.189605228
10.90291509
11.90184901
13.62162501
14.66094947
16.34120808
17.34517667
19.112395
20.12382851
21.82431056
22.85882844
24.54839314
25.60511114
27.25726951
28.37213933
30.01477051
31.08488564
32.81537998
35.57746164
36.87609484

The reason I have to use them is that i have to work out hkl values from them and the results i have got do not work with any example we have been taught.  I am 100% positive that these results are correct and my calculations are correct as they were done with an example with the demonstrator's example.  I would be very grateful if someone could point me in the right direction as I'm currently pulling my hair out trying to understand them.

Thank you

[cth]

I am not sure why you calculated sin²theta.


If you take Braggs equation  lambda = 2d sin theta  and modify it to express d function of theta:
d = lambda / (2 sin theta)


Calculate all d values. The biggest value (so smallest theta) corresponds to  h k l = 1 0 0. Then you look for systematic extinctions to determine the lattice. You can calculate d ratios to find patterns you talked about.