like i have made NiO/ZnO nanocomposite then how can differentiate that it is composite or doping is occurring on the basis of XRD.
In principle:
1) A nanocomposite is a multiphase solid material, and hence the XRD pattern should show diffraction peaks assignable to (at least) two crystaline solids; for instance NiO (NaCl structure type) and ZnO (wurtzite).
2) A doped material should show only the diffraction peaks corresponding to the major
component; for instance those of the wurtzite-type structure in the case of Ni-doped
ZnO, which would be slightly shifted (See, e.g. the enclosed article)..
Note however that, depending on the chemical composition (percentage of NiO and ZnO) and the temperature (and time) at which the sample was treated, several of the above phases may appear (simultaneously) in the final product.
In principle:
1) A nanocomposite is a multiphase solid material, and hence the XRD pattern should show diffraction peaks assignable to (at least) two crystaline solids; for instance NiO (NaCl structure type) and ZnO (wurtzite).
2) A doped material should show only the diffraction peaks corresponding to the major
component; for instance those of the wurtzite-type structure in the case of Ni-doped
ZnO, which would be slightly shifted (See, e.g. the enclosed article)..
Note however that, depending on the chemical composition (percentage of NiO and ZnO) and the temperature (and time) at which the sample was treated, several of the above phases may appear (simultaneously) in the final product.
In case of nanoparticles the base of xrd peaks are broad owing to their small size.
I agree with prof. Carlos, but there are some exceptions to this rule.
1. Your material is a solid solution, but the crystal lattice has a high concentration of defects. Then the effects of broadening can "mask" the peak's shift, so you won't be able to discern exactly whether you have pure compound or solid solution.
2. Your material is a composite, but the particles of the second phase are either extremely small (for example, atomic clusters in mechanochemically synthesized pseudo-alloys) or are in a small number (less than 2-5%). XRD won't usually be able to detect such phases.
So if you have doubts, perform TEM with SAED - the resolution is orders of magnitude smaller.
Dear Pooja,
Have you compare your XRD pattern of your samples with the known pattern from crystallographic database? I think you can check it first.
Good luck
In case of doping the XRD pattern will shift for the host, (without any extra pattern from dopant material) but in case of composite or alloy you will get XRD pattern for all the material in that sample.
Alloy or composite just mixture of materials, so you will see xrd pattern for all the materials.
Doping is replacement of atoms in original matrix, so you will see alteration in XRD pattern of matrix material. There will be no doped material's pattern.
Dear Pooja,
A nanocomposite is a mixture of different material with different phases, and doping is also a mixture of differential material but single phase, hence the XRD pattern should show diffraction peaks related to all the phases for nano-composities but in case of doping peak shift is observed from the host material. Further, peak broadening for both the cases is mostly depends upon particle size (some other reason also possible ).
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