Manifestation of quasi-symmetry of the cation sites of Gd2SiO5, Y2SiO5, and Lu2SiO5 in the spectra of the impurity ion Pr3+

The quasi-symmetry of the inequivalent cation sites in the crystals Gd2SiO5, Y2SiO5, and Lu2SiO5 is established on the basis of an analysis of the features of the low-temperature optical spectra of the impurity ion Pr3+. One type of cation site of the crystals Y2SiO5 and Lu2SiO5 manifests the quasi-symmetry of a distorted octahedron, and the other type, that of a distorted tetrahedron. The parameters characterizing the energy spectrum of the free Pr3+ ion in the crystalline field of the cation sites are determined. (C) 2001 American Institute of Physics.