Theoretical study of trigonal Fe3+ center in SrCl2:Fe3+ system

The presence of Fe3+ centers with trigonal symmetry in chlorinated SrCl2 crystal is an interesting phenomenon. By diagonalizing the complete energy matrices for a d(5) configuration ion in a trigonal ligand-field and simulating the EPR low-symmetry parameters D and (a - F) simultaneously, the local lattice structure around trigonal Fe3+ center in SrCl2:Fe3+ system has been studied. It is shown that Nistor et al. s viewpoint about replacement is right, but the Cl- ion along (III) axis around the Fe3+ center is replaced not by an O2- ion but by some negative ion with effective charge to be less than that of Cl- ion. Our results indicate that when the ratio of the effective charge of the negative ion to that of Cl- ion is 0.8 as well as the distortion angle of the upper triangle is Delta theta= -4.682 degrees, the EPR parameters D and (a-F) can be explained satisfactorily. (c) 2005 Elsevier Ltd. All rights reserved.