Dear friend Ilhan Danaci

I hope this message finds you well. I wanted to follow up on your recent observation regarding the shift of the XRD (002) peak from 26° to 23° in your single-walled carbon nanotube (SWNT) samples. This is an intriguing result, and I believe a systematic exploration could help uncover the underlying causes.

To guide our discussion, I’ve outlined several key questions:

What is the significance of the (002) peak in XRD analysis of SWNTs, and how does it relate to interlayer spacing and structural arrangement?

Could structural changes—such as interlayer expansion from oxidation or functionalization—be responsible for the observed shift?

Is it possible that synthesis or treatment processes introduced defects or turbostratic disorder, thereby affecting the XRD pattern?

How might tube–tube interactions or changes in bundle morphology influence the peak position?

Could sample preparation or residual strain have played a role in altering the lattice parameters?

Are there relevant studies or literature reports that document similar shifts under comparable conditions?

I’d appreciate your insights on these points, especially regarding any recent treatments or preparation methods used. If you have supporting data or references, please share them at your convenience. This will help us pinpoint the most likely factors contributing to the shift.

Looking forward to your thoughts.

Best regards,

kaushik

Dear Ilhan Danaci

The shift of the (002) peak to around 2θ ≈ 23° in your SWNT samples is indeed interesting and has been occasionally reported in the literature. A shift of the (002) peak to lower angles indicates an increase in the d-spacing, as described by Bragg’s law: nλ=2dsinθ

This is typically attributed to an expansion of the inter-tube (interlayer) distance. Chemical treatments such as oxidation, acid treatment, or functionalization can introduce oxygen-containing groups onto the tube surfaces, increasing repulsive forces between tubes and thus widening the spacing.Additionally, structural disorder introduced during or after synthesis can lead to turbostratic stacking, where the tubes are less regularly packed. This disorder can also cause the (002) peak to broaden and shift to lower angles in the XRD pattern.Based on your observations, the shift of the (002) peak is most likely due to increased inter-tube spacing and/or structural disorder. The sample’s processing history (e.g., acid treatment, oxidation, or functionalization) can further enhance this effect. You may consider supporting these findings with additional characterization techniques such as Raman spectroscopy or TEM to confirm the presence of disorder or changes in tube spacing.

Relevant literature you may cite:

• AL MASUD, M. A., & CHOWDHURY, M. A. H. (2019). ANALYZING THE EFFECT OF ANNEALING TEMPERATURE ON THE CRYSTALLINE PARAMETERS OF ZnO NANOPARTICLES.
• Steele, J. A., Solano, E., Hardy, D., Dayton, D., Ladd, D., White, K., ... & Toney, M. F. (2023). How to GIWAXS: grazing incidence wide angle X‐ray scattering applied to metal halide perovskite thin films. Advanced Energy Materials, 13(27), 2300760.
• Yeh, J. W., Chang, S. Y., Hong, Y. D., Chen, S. K., & Lin, S. J. (2007). Anomalous decrease in X-ray diffraction intensities of Cu–Ni–Al–Co–Cr–Fe–Si alloy systems with multi-principal elements. Materials chemistry and physics, 103(1), 41-46.
• Bindu, P., & Thomas, S. (2014). Estimation of lattice strain in ZnO nanoparticles: X-ray peak profile analysis. Journal of Theoretical and Applied Physics, 8(4), 123-134.

Best regards.

Thank you very much for your answer, Hocam. I will look into it in detail.

Ilhan Danaci, in your original question, you include

"The SWNTs are [pristine / acid-treated / oxidized / functionalized — please select the one matching your process]." (brackets in original)

It looks like you used AI to assist with writing your question - which is fine; it is AI generated answers that are so annoying! - but forgot to go back and specify this. Telling us whether the samples in question are pristine, acid-treated, oxidized, or functionalized would make possible much better answers.

BTW, I find it mysterious that Kaushik's answer would get two recommendations, since it is just an AI generated restatement of the question!

Thank you for your warning. Yes, I received support with the translation and writing of the text. That part was overlooked. The samples were analyzed by XRD as pure SWNT.

Ah, so as you read over the responses above, you can focus on the factors that refer to things introduced during synthesis and skip over factors contributed by functionalization, oxidation (unless oxidation could occur due to unintended oxygen presence due to leaks or impurities).

Yes, we can do it the way you said. I corrected the question accordingly.