Paramagnetic centers of vanadium and iron in Na-=SUB=-5-=/SUB=-AlF-=SUB=-2-=/SUB=-(PO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=- single crystal

Abstract

The orientation behavior of the EPR-transitions of uncontrolled V4+ (S=1/2) and Fe3+ (S=5/2) impurity centers in a Na5AlF2(PO4)2 single crystal doped with chromium has been studied. The parameters of the spin Hamiltonian of these centers are determined both in the laboratory (crystallographic) and in the local coordinate systems. Based on the fact of the existence of mixed vanadate-phosphates and taking into account the orientation of the principal axis V4+, it was concluded that vanadium replaced the position of phosphorus. The closeness of the principal axes of the fine structure tensors of the second and fourth ranks of Fe3+ centers to the F-F direction of the fluorine-oxygen octahedron surrounding the iron ion was found. Keywords: impurity ions, paramagnetic resonance, hyperfine interaction.