XRD will help you ID any preferred orientation in your sample.

Try Laue Transmission with some dental film, nothing fancy :-) Only a century or so old. I bet you, you have never ever in your life seen or heard of dental film use in the XRD lab, have you? A tool more advanced than many 2D XRD detectors and their use today.

https://www.flickr.com/photos/85210325@N04/10515372183/in/album-72157645018820696/

I think, it will be trivial to identify the preferred orientation especially from XRD especially in this case. Since, CNT are of C-species which has low atomic scattering factor. In most of the cases, the preferred orientation is observed clearly by significant variation in the intensity of Bragg peaks especially at higher angle. Hence, it may be bit difficult to exactly pin point the issue. (However, there may be some advanced detectors and also different geometry to resolve such things, rather than a normal 2-D detector frequently used in Lab source XRD (synchrotron source may be helpful)

Rather I  think Raman Spectroscopy, could  provide better information in such issues..

Never heard of Raman Spectroscopy and its use in quantifying "preferred orientation" yet. Please post some literature references or send PDF file to:

[email protected]

https://www.flickr.com/photos/85210325@N04/7944785794/in/album-72157632728981912/

Mauricio, precisas realizar tua pergunta um pouco mais especifica, o pessoal aqui pensa que estais falando de nanotubos de carbono ... Abracos.

Just perform XRD, then compare with the bulk patterns.

you might observe widening in the peaks, and this due to the low dimension of the nanostructures you have.  Consider also Scherrer formula and compare it to SEM images for consistence

regards

Hamad 

"I think, it will be trivial to identify the preferred orientation especially from XRD especially in this case."

Sure thing! If you just rotate the flat "powder" sample 90o about its surface normal and observe changes in relative intensity of the diffractogram, that  would indicate presence of "preferred orientation". However, quantifying it or determining ODF (Orientation Distribution Function) or texture coefficient are not "so trivial". Especially, using the conventional "spatially blind" equatorial scan linear diffractograms with a DINOSAUR 0D "pont counter".

Do review the following RG posts for examples of conventional diffractograms from CNT and more:

https://www.researchgate.net/post/Is_this_a_reasonable_way_to_eliminate_effects_of_sample_surface_misalignment_with_the_diffractometer_axis_Theta-2Theta_Diffractograms?_tpcectx=profile_questions

https://www.researchgate.net/post/Is_it_possible_to_quantify_texture_co-efficient_for_Aluminum_foil_02mm_200um_thick_using_transmission_Laue_XRD_Images?_tpcectx=profile_questions

OK, my sample is not a CNT, my simple is independent semiconductor nanotubes (tantalum oxide). The treatment may be considered the same? Thank you all.

What dimensions?

I think a major challange is the size of the nano tubes (also aspect ratio). I guess this is the same Ravi was asking for. If they are too small or anisotrop you do not get clear intensities which might be difficult to evaluate. Especially when the thickness of a coating is investigated and shows beside different thickness also a texture gradient. I would highly recommend to become familar with samples which show no gradient, which are no nano materials, and which have a simple preferred orientation. ODF determinationo is already under these circumstances very challanging and not straightforward. Only because there are programs it does not mean that one can simply use them. There are entire groups busy in this field for years or decades already, and this not because they have no idea how it works. In contrary!

The best would be to ask whether there is someone who already did it and who could support you by at least one measurement. Everything else will be (from my point of view) less efficient. You need to be excellent (!) in XRD, in nano materials, and in texture description. It is very unlikely that you can become this is 3-5 years. :-) 

the nanotubes have a height of 8-9 microns, and wall thickness of 40-45 nanometers.

Post available photographs and micrographs of your sample. How do you plan to prepare samples for XRD?

I suggest, pick up sample, if powder, with sticky side of some scotch tape right out of the container it is in for Laue transmission or reflection mode observations. At least, you won't  introduce any preferred orientation by "smearing" or "pressing" the powder. XRD is highly sensitive! Also consider SAXS measurements to cover all the potential ranges of Nanostructural periodicities.

If grown on flat substrates, XRR may help as well.

• the nanotubes have a height of 8-9 microns, and wall thickness of 40-45 nanometers. Got micrographs?
• semiconductor nanotubes (tantalum oxide). What substrate material?
• Got references?

So I would assume an anisotropic broadening of reflections since the coherence length is for all hkl different, i.e. your "grains" are highly different from being spheres. However, as long as your diameter is correct, it might work. If it is smaller you will observe very sharp but also very broadened peaks which are overlapping. The background determination becomes difficult since much of the background will be intensity of the broadened peaks. Another problem is the sample "prep", although I assume you are having layers, i.e. no powder at all. In case you have freestand nanotubes you will have a very strong [001] fiber texture, i.e. in Bragg-Brentano geometry you will observe only 00l reflections but nothing else. Therefore my question: what do you want to know exactly (if the preferred orientation is actually already clear)? Are the nanotubes not exactly perfect? Or do you expect some kind of single crystalline arrangement (coating on a single crystalline substrate?)  

I wonder if only with the data of X-ray diffraction I can discuss some preferred crystallographic preferred orientation, once I clearly detect the peaks. My problem is that my nanotubes lack substrates, so the variation of intensities of peaks may be due to random arrangement of the nanotubes. Knowing this, I can make this kind of discussion? Thanks,