We consider the ESR of Co2+ in different environments: in an regular octahedron (Co2+ in a MgO crystal), in a deformed octahedron (Co2+ in single crystals and powder samples of NH4NiPO4.6H2O) or in a trigonal bipyramid (Co2+ in powders of Co2(OH)PO4 and Co2(OH)AsO4). We study the effect of the non-cubic crystal fields in the ESR of Co2+ in the deformed octahedron, by employing the normal modes of this structure to simplify the systematic study of the effect of these fields. A similar study was done for the deformed trigonal bipiramid, and it was necessary to derive the normal modes of this complex that are relevant to our problem.
ESR; Crystal field
