An empirical relationship describing the radial dependence of the non-dipole part of the anisotropic constant for the ligand hyperfine interaction in alkaline-earth fluorides was proposed. This relationship was used for calculating the distances between the magnetic ion and the F ions involved in its nearest environment. The results of the calculations were in good agreement with the values obtained by other methods for both cubic and tetragonal F centers in these crystals. The distances from the magnetic ion to different groups of non-equivalent fluorine ions of the nearest environment in Yb3+ trigonal centers of SrF2 and BaF2 were determined. It was found that the Yb3+ ion was slightly displaced along the trigonal axis away from the compensating F ion.

A Method for Estimating the Local Lattice Distortions Near a Magnetic Ion from Ligand Hyperfine Parameters - Yb3+ Trigonal Centers in SrF2 and BaF2. T.A.Gavasheli, D.M.Daraseliya, D.L.Dzhaparidze, R.I.Mirianashvili, O.V.Romelashvili, T.I.Sanadze: Physics of the Solid State, 2006, 48[1], 58-62