Crystalline electric fields in hydrated Co 2+ salts

Abstract

The theoretical expressions for the magnetic susceptibility and anisotropy of Co²⁺ ion in hexahydrated salts have been derived on the basis of Abragam & Pryce’s theory and compared with the experimental results for three Tutton salts. Agreement with experiment is very good provided it is assumed that for each salt the value of the asymmetric field separation A varies with temperature. It appears that the magnitude of A depends more upon the alkali radicals than upon the acid radicals. The value of the spin-orbit coupling coefficient ζ in Co²⁺ salts is practically the same as the free ion value, indicating very little overlap between the 3d-Co²⁺ and s. and p-O^2- charge clouds. The cubic and anisotropic field parameters G, H and I are different for divalent Co²⁺ and trivalent V³⁺, as is to be expected.