EPR parameters and local lattice structure study of trigonal Fe3+ center in CsMgCl3 crystal

The EPR parameters and local lattice structure study of trigonal Fe3+ center in CsMgCl3 crystal has been performed on the basis of the complete energy matrices for a d5 configuration ion in a trigonal ligand field. It is indicated that the local lattice structure around a trigonal Fe3+ center has an elongation distortion along the crystalline c-axis, and the elongation magnitude of trigonal Fe3+ center is larger than that of the host Mg2+ ion. This may be ascribed to the fact that Fe2+ ion which exists in the as-grown CsMgCl3 crystal substitutes for Mg2+ ion. The Fe2+ ion whose radius is larger than that of host Mg2+ ion pushes the chlorine ligands upwards and downwards, respectively. Finally, the Fe2+ ion is changed into Fe3+ ion by X-ray irradiation. Simultaneously, for the trigonal Fe3+ center in the crystal, the local lattice structure parameters, R = 2.535 Å and θ = 50.314°, are determined from our calculation, and EPR parameters b20, b40, and b43 also get a satisfactory explanation.