Determining the position of a dopant in a crystal lattice, specifically whether it occupies a tetrahedral or octahedral site, involves a combination of experimental techniques and theoretical calculations.

Exp: XRD, Neutron Diffraction, EXAFS, EPR.

Theoretical: DFT and MD

Use software tools for XRD refinement (e.g., GSAS, FullProf) and EXAFS analysis (e.g., IFEFFIT, Artemis) to extract detailed structural information.

X-Ray Diffraction (XRD): This technique analyzes the crystal structure by measuring the X-ray scattering pattern. By comparing the obtained pattern with simulations or reference data for the undoped material, subtle changes caused by dopant position can be identified. Shifts in peak positions or intensities can indicate changes in bond lengths and atomic positions, potentially revealing the dopant site.

Rajalakshmi Rajendran This is a good question. I will give you the answer by giving a practical example. Suppose you have marbles of different sizes, Put them all in a box, and then shake the box. How will they arrange it?

So according to me, dopant atoms can occupy tetrahedral or octahedral positions depending on the place where they can stabilize the crystal, i.e., minimize the crystal energy. The term "Minimizing the energy" means where the repulsion between the electron clouds of atoms is at its minimum and maintains charge neutrality.Only from the theoretical calculation, people can suggested where dopand can go inside the crystal structure. Doping means that dopant atoms are lesser in number as compared to the other atoms. So dopants will adjust to the already-existing crystal structure( i.e., without doping). E.g., in the case of Ni doped Co3O4, Ni occupies the tetrahedral sites, while Co occupies the octahedral sites.

To confirm,the crystal structure, you have to do the XRD and match those peaks with JCPDS data whereas XPS can give give you the ratio of different atoms present.

XRD or neutron diffraction will NOT be sensitive enough if the dopant level is as low as would be technologically relevant for doping (ppm). You would need a technique that can chemically identify the dopant atoms and so isolate their signal from that of the surrounding matrix , e.g. NMR, Raman, EELS etc, and then look at their local microstructural environment. As a rule of thumb, ions with sp3 configuration will most likely go to tetrahedral and trivalent ions to octahedral sites (in oxides). Single of bivalent atoms are more likely to form point defect complexes.