I am working on XRD analysis of the clay minerals from the sea sediments. My XRD pattern shows very high counts at the start of the XRD pattern (3 degree 2 theta) which is very unusual. The counts then slowly come down to normal values with increasing 2 theta angle. Also the XRD peaks are not very sharp. I checked the other clay minerals XRD patterns in various publications and find out that my XRD pattern has a problem. what might be the reason for such a high counts at the start of XRD pattern. Is the problem related to XRD machine or something wrong with my sample.
Thanks
Dear Muhammad Sarim ,
At such a low angle, 3o 2theta, the source (X-ray tube) directly aligns with the detector. It doesn't matter if in a theta-theta or theta-2theta configuration.
The direct detector irradiation is inevitable. If no reason indicates the necessity to star at such a low angle, standing at about 5o 2theta will promote a high decrease in the effect and reduce the direct detector's irradiation.
Concerning your sample, 4.5o 2theta is going to work very well.
The setup may use filters; however, the result is only partial; the best solution is to increase the starting angle.
Best regards,
WNM
Nothing wrong with your machine and clay samples. It always happens when clays do not contain high spacing minerals having values > 17/18 angstrom.
Dear Muhammad Sarim ,
At such a low angle, 3o 2theta, the source (X-ray tube) directly aligns with the detector. It doesn't matter if in a theta-theta or theta-2theta configuration.
The direct detector irradiation is inevitable. If no reason indicates the necessity to star at such a low angle, standing at about 5o 2theta will promote a high decrease in the effect and reduce the direct detector's irradiation.
Concerning your sample, 4.5o 2theta is going to work very well.
The setup may use filters; however, the result is only partial; the best solution is to increase the starting angle.
Best regards,
WNM
Wagner Da Nova Mussel Thanks you sir for such a detail answer. However, i just want share that on the same machine with same settings, i analyzed samples and there were no high counts. However that sample i prepared using a different method and chemicals...while this sample i have prepared with just using HCl, so i was thinking if it has something to do with the sample preparation method.
Dilip Kumar Pal Wagner Da Nova Mussel , This is XRD pattern from the same machine and same setting but sample prepared by a different method... here i have no high counts and also the peaks are so sharp
Dear Muhammad Sarim ,
Just adding some more discussion, the scattering and high count at a low angle are very close, comparing the previous and last experiment. Still present the detector irradiation effect.
Nevertheless, the peak intensity at about 12.5o 2theta has increased; it will relatively decrease the high counts at a low angle, bounce effect, (I12.5/I3 >> 1, now is higher) , which is still basically the same, about 10.000 counts.
Indeed, the use of HCl in sea sediment will eliminate several carbonated phases; they are immobilized by plankton. Most of them are amorphous due to the velocity of nucleation; the background will decrease by the scattering decrease.
Best regards,
WNM
Dear Muhammad Sarim
The reason is probably the presence of interstratified clay minerals of the illite-smectite type with a relatively low ordering. You can try saturating the sample with ethylene glycol.
Dalibor Matýsek Thank you professor for such a good suggestion. really appreciate it
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction