ESR investigation of an ionized Mn2+-F centre pair in KMgF3

Abstract

When KMgF3:Mn is irradiated at room temperature, Mn2+-F-centre pairs are created. A subsequent UV bleach at 77K ionizes the F electron leaving an Mn2+-fluorine vacancy centre. The ESR spectrum associated with this centre exhibits a large crystal-field splitting with principal axes along the (100) directions. A small deviation from purely axial symmetry is explained by considering the distortion of the remaining five fluorine ions from their normal lattice positions. A pulse anneal study indicates that the Mn2+-fluorine vacancy centre dissociates at 185K.