Electron paramagnetic resonance studies of divalent cobalt ions in some chloride salts

Abstract

EPR measurements of the ground state g-values of Co2+ ions at sites of trigonal symmetry in CdCl2, CdBr2, CsCdCl3, MgCl2 and K4CdCl6 are reported. Two distinct axial EPR spectra are observed in CsCdCl3, corresponding to the two crystallographically inequivalent Cd2+ sites. In the case of K4CdCl6 one axial spectrum and a second spectrum of lower symmetry are observed. All of the other crystals display single axial spectra. A superposition model analysis of the crystal-field parameters for CdCl2:Co2+ gives intrinsic parameter values of B2=-11000 cm-1 and B4=-4060 cm-1. These values are employed in a calculation of the crystal fields for Co2+ ions in CsCdCl3, K4CdCl6 and CsMgCl3, using the empirical superposition model for nearest-neighbour interaction and the point-charge model for contributions from more distant ions.