To the structure of the trigonal center of Yb3+ ion in hexagonal perovskite crystal RbMgF3

EPR and optical spectra are used for the analysis of distortions of a crystal lattice in the vicinity of an impurity ion Yb3+ of trigonal symmetry in RbMgF3 crystal. Within the framework of the superposition model, it is established that three F- ions of the nearest-neighboring octahedron, located symmetrically along the threefold axis of the trigonal center, move away from the impurity ion and have considerable angular deviations from the symmetry axis of the center. The next three F- ions, which enter the other octahedra, shift towards the paramagnetic ion and, on the contrary, come a bit closer to the axis.