for example In the carbon nanotubes decorated with metal nanoparticles, can guess or calculate the approximate value of metal from the peak intensity ratio?
There should be a relationship, but the question is how to get this relation.
When assuming the CNTs to be one phase and the metal NPs being a second phase (or as a composite consisting of two components) one should be able to solve this challenge by refinement techniques:
Experts in XRD refinement may comment in more detail.
You may solve this task by home made calibration samples, exhibiting well known mixtures of CNTs and metal NPs. There is no necessity to bind the NPs onto the CNTs. However I must admit that this is not an easy task.
Peace be up on you, your question's readers and all RG members.
There is a big difference between the "amount of matter" and the "thickness of matter" in the XRD spectrum. XRD instrument involve holder with certain dimensions, this is the important thing due to the penetration depth of XRD. As the XRD instrument holder is full with the focused material, this is enough and this is the critical amount of matter needed. It is differ from one instrument to other. The excess of the amount of matter more than the instrument's sample holder needed is useless.
You may need to process XRD many times for your matter if you prepare it many times by the same technique to check the structural stability, or to study the effect of preparation method.