Since we synthesized nanoparticles Со in the surfactant solutions. They need to clean out the well of reagents and surfactant in alcohol and dried under vacuum. The XRD 2theta =44.1, 51.6, 75.81 are in good agreement with JCPDS No. 01-1255.

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Okay sir ..Thanks. And, I tried it by just coating colloidal NPs over Pyrex substrate. But did not get any obvious peaks.

See magnetite coated polypyrrole

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Thanks a lot sir for adding important knowledge to my account....But when I did nickel nanoparticles synthesis via colloidal route and, then XRD was able to show first two peaks..But in the case of Co-NPs, peaks did not appear. 

However, when I did EDX for both samples then it showed Co- and Ni- in both individual samples respectively.

So, my point is how surfactant and protecting agents are reason for blocking XRD not to show peaks?

Thank you,

Regards:

We need more accurate experimental data for this discussion.

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Yes sir.. Correctly said.

XRD can be used to identify crystalline samples. If the size of crystallites is very small the lines are extremely broad and can disappear, An electron diffraction (SAED) in microscope may be of some use in this case. Amorphous nanoparticles have a broad peak and typically can be used to identify a crystalline structure. If the coating is not crystalline XRD will show nothing. Additional spectroscopic data may ne required.

Correction:

Amorphous nanoparticles have a broad peak and typically cannot be used to identify a crystalline structure.