Analysis of the Structure of Tetragonal Oxygen Centers Associated with Yb3+ ions in the KMgF3 Crystal

Abstract

The parameters of the crystal field of the tetragonal oxygen center associated with a Yb3+ ion in the KMgF3 crystal found previously in a study of optical and ESR spectra are applied to analyze lattice distortions in the vicinity of the impurity ion and the O2- ion compensating for the excess positive charge. Within the super-position model, it was ascertained that the Yb3+ ion and the neighboring ions of fluorine and oxygen on the axis of the center shift significantly along the direction from the O2- ion to the Yb3+ ion during the formation of the tetragonal oxygen center. As this takes place, the distances of both (fluorine and oxygen) ions from the impurity ion increase. The four F- ions of the nearest octahedral neighborhood of Yb3+ that are arranged symmetrically in the plane perpendicular to the axis of the center slightly recede from the axis. © 2003 MAIK "Nauka/Interperiodica".