If in a lattice structure with lower symmetry, one atom is surrounded by atoms with different distances in the unit cell, what will be the the nearest neighbor distance and number of nearest neighbor, i.e., co-ordination number?
Typically, in a crystal with lower symmetry almost all the interatomic distances are different, take the case of FeVO4, the most stable phase at ambient conditions has P-1 symmetry. In this crystal is difficult to establish the nearest neighbor. Instead, it is defined the coordination which refers to the number of atoms that are linked to an atom. In the case of FeVO4, there are three inequivalent Fe atoms, one with coordination 5 and 2 with 6. While V atoms have the coordination of four.
Here is a paper of FeVO4
Article Stability of FeVO4 under Pressure: An X-ray Diffraction and ...
Regards
Sinhue Lopez, Thanks for the reply. I had an query regarding your answer. What are you meaning by inequivalent? Its srtucturally inequivalent or chemically?
Dear Santanu,
The crystal structure of a compound such as FeVO4 is defined by the lattice parameters (a, b, and c), angles (alpha, beta, and gamma), and the Wyckoff positions (WP), in this case there are three WP for Fe, three for V, and twelve for O. So, there are three inequivalent positions of Fe. That is regarding the structure. If you see the paper you will find that two Fe atoms has a coordination of six and the other one has a coordination of five. This means that the electronic structure will be different for FeO5 and FeO6 polyhedra.
Regards
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