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By analyzing the EPR spectra of Fe(3+) ion in the fluorinde glasses, the local lattice structures around impurity Fe(3+) ion in MF(3):Fe(3+) (M = Al, Ga) systems have been studied by means of diagonalizing the complete energy matrices of the electron-electron repulsion, the ligand-field and the spin-orbit coupling for a d(5) configuration ion in a trigonal ligand-field. Both the second-order and fourth-order EPR parameters D and (a-F) are taken simultaneously in the structural investigation. The results indicate that the local lattice structure around octahedral Fe(3+) center has an expansion distortion for Fe(3+) in MF(3):Fe(3+) (M = Al, Ga). The expansion distortion may be ascribed to the fact that the radius of Fe(3+) ion is larger than that of Al(3+) ion and Ga(3+) ion, and the Fe(3+) ion will push the fluoride ligands upwards and downwards, respectively. The local lattice structure parameters R = 1.927 A, theta = 55.538 degrees for Fe(3+) in AlF(3):Fe(3+) and R=1.931 A, theta = 56.09 degrees for Fe(3+) in GaF(3):Fe(3+) are determined, respectively, and the EPR spectra of the MF(3):Fe(3+) (M = Al, Ga) systems are satisfactorily explained. (C) 2009 Elsevier B.V. All rights reserved.