Are you performing powder diffraction by milling your nanotubes or are your samples still on the substrate ?

I agree with Christopher - if the ZnO-nanotubes are still fixed on the substrate, then a predominant (preferred) orientation of the tubes is not unlikely - such phenomena are observed in many cases for nanorods, nanowires or nanotubes.

So if you remove the ZnO from the substrate, mill them in a mortar and re-investigate them with XRD, then you should normally see the (002) reflection.

Good luck, Dirk

Thanks ,

The samples transport to carbon tap as support before removing the AAO template and take it to XRD equipment

Is it likely that the original structure was preserved during removal of the template? How do you remove the template? But it may happen that the ZnO sticks on the carbon tape in a preferred manner ...

One additional comment - do you have access to a scanning electron microscope with sufficient resolution? If so, I would strongly recomment some SEM investigations ...

Dirk could be correct here, but I have also seen preferred orientation in other thin film materials dependant upon the substrate used and the orientation is usually caused by the interface between the two different materials.

Why don't you try a different substrate, say NaCl for example, then float your nanotubes off using either warm water or acetone and see if the XRD from these gives you similar results.

It may also be worth using TEM in diffraction mode to analyse your structure and see if this matches your XRD results from both sample sets.

Thanks a lot,

After deposing of ZnO/ALD on AAO and because the thickness of template is thin around 1-1.5 um ,so to avoid damage the ZnO/AAO during template removing with NaOH solution I put carbon tap on the surface and then the ZnO will stick on it and I checked it in SEM to sure the ZnO is available not remove ,then I checked in XRD .AlsoI used ZnO /AAO /Si without used carbon tap but the same results in XRD .

I have checked in TEM ,the results indicated the polycrystalline from SAED but unfortunately I did not obtain the orientations because there is errors in software .

Dear all

I can sent you images of ZnO which checked in SEM

If you have a 'standard calibration' on the TEM, the most obvious being a thin gold film, you can then use this to work out your relative camera length and then knowing your accelerating voltage and resulting wavelength, you can use written calculations to work out the d-spacings and thus the indices of the diffraction rings (or spots).

Do the same for XRD, do hand written calculations for the peaks you have to calculate your d-spacings and lattice parameters, only start refining using software when you are sure you have a good idea of what is there.

Too many people dive in with software nowadays - my old Professor always swears by using hand written calculations until he knows what is there, then he would ask for validation or verification by means of software analysis.

By all means upload your SEM images - have you any images of your SADP's you got from TEM ??

Thank you very much,The TEM here not perfect ,and I put here the images of SEM ,XRD and TEM

SEM

TEM

About the TEM measurment I can not use it by my self there is a another person do that

but about XRD I can calculate the orientations from the peaks

It does look like preferred orientation of the growth of the nanotube. I have done a bit of reading around - you have the [100] peak at ~31 and the [101] at ~36 but you are missing the [002] suggesting a preferred a-plane orientation.

Have a look at this to see what I'm trying to explain by choice of substrate and how it affects orientation (which is why I'm suggesting a different substrate earlier), I know ZnO has this property (as it forms Wurtzite or Zincblende) structures.

See this link and the attached paper....

http://www.hindawi.com/isrn/nanotechnology/2012/372505/

Thanks a lot ,yes you right I have all the orientions of ZnO but missing (002) this this my problem .Do you know before , I synthesized ZnO thin film from thermal solution and the product was powder and checked it in XRD there was (002)

but know I working with ALD and AAO but I did not (002) in XRD spectra

Thank you ,I will read the link and the article I hope will find the solution .

Detecting & Quantifying Preferred Orientation! This is perhaps the best case you could make for obtaining 2D diffractograms as opposed to the ubiquitous 1D equatorial diffractogram using a 0D scintillation/point detector. I'm still reading through all the comments.

Great question Samar! Excellent display of data. Best way to leverage collective intelligence.

[email protected]

Cheers Ravi - always nice to see constructive comments. I've examined Wurtzite and Zincblend structures using the the Icsd database. I think Ive got this one correct and it needs a different substrate to identify the issue. This is certainly interesting but needs more work.

Dear Ravi ,Thank you very much ,your comment is encourage me.

Dear Christopher ,thank you and I am reading the artich and the linke of ZnO that advised me read ,but the substrate and method are different ,I chenged the substrate by using Si with connected template I mean AAO on Silcon and I have checked in XRD also the 002 not indicated.may be the ALD method ?

I think it may be possible that it is a property of the nanotube itself, as if you look at your XRD I am fairly sure you have a small (intensity) reflection for the [103] plane - your pattern is only missing the [002] reflection which is indicative of preferred growth orientation - this could be due to the nanotube possessing both short range order and possibly long range order which results in a superlattice effect - I have seen this occur in magnetic alloys (where say for a bcc structure the [110] reflection is missing but the [220] is present indicating a lattice of double the normal parameter).

Here is a standard diff pattern for ZnO, yours is not dissimilar, just the one reflection difference.

It would be interesting is you repeat the XRD but go to much higher angles, i.e. up to 150 degrees and see if you can see the [004] reflection - as this would indicate a superlattice reflection.

Maybe Ravi could suggest a technique here as it would seem that he may have more experience of quantifying the data.

Suggestion: Rotate the sample surface w.r.t. the incident beam and repeat XRD. If it is due to preferred orientation then you'll see the (002) reflection at some point. See the example of preferred orientation in Al foil:

http://www.flickr.com/photos/85210325@N04/7944785794/

Best is to use photographic film to capture the 2D XRD pattern with a "point source". (Assuming you do not have access to 2D detector). Ideally, the XRD should be conducted in the transmission Laue mode. However, if your substrate is thick then use the reflection geometry and you would be able to see the effect of any possible preferred orientation using photographic film. The most likely reason that the TEM diffraction pattern is not sensitive to the preferred orientation is due to the small sampling size (tear drop) in TEM compared with XRD.

http://www.flickr.com/photos/85210325@N04/7944785794/

Here are the two (Samar's & Chris') XRD patterns compared:

http://www.flickr.com/photos/85210325@N04/9686343070/

You seem to be saying that the ZnO was transferred to a Carbon tape? Is that correct? Then you need to run a XRD scan of just the tape alone as well. I must assume the XRD is done in the transmission mode.

1. What is the incident beam shape/size/conditioning?

2. Transferring the film will change the insitu strain state of the film.

http://www.flickr.com/photos/85210325@N04/9686343070/

I am so sorry late to answer ,because there is errors in software of my computer.

Dear Christopher yes ,you right may be that is property of nanotube ,yes there is a small (002) peak ,and I have in the spectra other ZnO orientations and always in all data XRD (101) is strong while 002 is very weak.

In last year I have fabricated ZnO nanowires as powder and checked it in XRD .you can see the spectra here there is peak of 002 compare, with my ZnO nanotubes

Dear Ravi good suggestions , the thickness of ZnO /AAO is around 1-2 um in fact not thicker .as I mentioned up I used Si with ZnO and the same results ,where I checked the samples in different XRD in Berlin and Ilmenau.

And

I will scan XRD of only tap as you suggested and I will extended the scan theta to more 100 ,in fact I do not have permission to check by myself.I give the samples and wait the data

Acquire 2D XRD data and quantify preferred orientation. Use a "known standard" (preferably internal) to calibrate XRD tool. When posting XRD data in 2-Theta, please include other experimental details such as (when possible):

1. Incident Beam wavelength/energy dispersion (monochromation apparatus) and angular dispersion (slit dimensions). I have to assume all displayed diffractograms are similar wavelength (Cu Target, with Ni filter?).

2. Optics/Geometry used. Preferrably the equipment used. Transmission/Reflection. Diffractometer dimensions i.e., radius, sample to detector slit distance. Photos with scale would help.

3. Counting statistics (to establish SNR Signal-to-Noise Ratio). I notice the SNR was low for Sample 1: ZnO above. Why?

4. Angular resolution (related to step size and slits used).

5. Diffraction pattern of mounting substrate without the sample.

6. Sampling size based on beam size on the sample and subsequent slits used.

7. What are the annotated peaks below 30 degrees?

8. What is AAO?

9. What is your substrate thickness?

10. Do you have photographic film in your XRD Lab? Or is it extinct? Ever used it?

yes ,you are rghit ,I will check new samples and ask them to calibrate XRD tool before scanning ,may be helpful .

My profile photo today September 6th, 2013 is an example of the details that may be computed with even a tiny "dental film". In our case we were using our 25mm diameter real time 2D XRD imaging system: http://www.flickr.com/photos/85210325@N04/8706645521/

FoV- Angular Field-of-View (2Theta 130 degrees);

SDD - Sample-to-Detector Distance 6.94mm;

Lead (Pb) Beam Stop Dimension 6mm;

Incident Beam Size of 1mm diameter, Cu K Alpha with Ni filter;

Detector resolution of around 80um per pixel;

Calibrated Image: http://www.flickr.com/photos/85210325@N04/7977700644/

http://www.flickr.com/photos/85210325@N04/8706645521/

Calibration is a lot more than "may be helpful". It is quintessential to the proper use of XRD. Usually, it is assumed. I'd encourage you to "trust but verify" (Daviriyay nu proviriyay - Russian, as Ronald Regan used to say).

I sure you are professional in XRD , and I know I need more and more to understand mechanism of XRD ,thank you very much

LinkedIn Group: XRD Imaging for Materials Microstructural QC

Really appreciate your thoughts. Please feel free to join and post your query & information in our group as well:

http://www.linkedin.com/groupItem?view=&gid=2683600&type=member&item=268765048&qid=a5e5de34-6f48-4fa0-8b0a-d84f2b90b5cb&trk=groups_most_popular-0-b-ttl&goback=%2Egmp_2683600

http://www.flickr.com/photos/85210325@N04/9686931306/

BTW Si is an excellent standard to use! Is your substrate poly or mono crystalline?

Thank you very much ,I have appreciated in LinkedIn Group

About my sample AAO is amorphous,but the ZnO/AAO /AlD is polycrystalline in order to improve the structure ,I changed the tempr.