Hyperfine structure of Cr⁵⁺ EPR spectra in X‐irradiated potassium halide crystals doped with CrO and Ca²⁺

Abstract

The hyperfine structure has been investigated in the EPR spectra of X-irradiated KCl:CrOz-, Ca2+ and KBr: CrOz-, Ca2* crystals. Preliminarily spectra were simplified by means of heating the crystals up t o 400 K for KC1 and 440 K for KBr, that destroys the less stable Cr0i-e V i centers. It is ascertained, t h a t principal directions of 9-and Atensors do not coincide, and principal A-values are determined. Calculations, making use of the experimental meanings of 9-and A-tensor components, showed, that the degree of distortion of oxygen tetrahedra in CrOi-. Ca2+ . V: centers is almost the same in both KCl and KBr crystals; besides, these calculations suggest the existence of a strong covalent bonding between the central Cr5+ ion and four oxygen ligands in (3-034-ions.