Superhyperfine interaction in the trigonal center BaF2 : Gd3+ and the lattice distortion analysis in the vicinity of the impurity ion

The constants of the superhyperfine interaction of Gd3+ with the F-19 nucle ar spins in the first four coordination shells were determined from the END OR spectra of a trigonal BaF2 : Gd3+ center. These data were used for analy sis of the crystalline lattice distortions in the vicinity of the impurity ion. It was found that the largest displacements of fluorine nuclei occurre d in the vicinity of the ion compensator and the impurity ion. To calculate the anion positions within the first coordinate shell, whose electron-nucl ear interaction with Gd3+ depends considerably on chemical bonds in the Gd3 +F8- complex, an empirical model is used for the isotropic constants of the superhyperfine interaction of Gd3+ with fluorine nuclei in cubic centers, with allowance made for the impurity ion polarization. (C) 2001 MAIK "Nauka /Interperiodica".