19F ENDOR measurements of transferred hyperfine interactions in CsCdF3:Gd3+and CsCaF3:Gd3+

Abstract

The transferred hyperfine interaction parameters have been measured at 4.2K by ENDOR for five shells of 19F neighbours around Gd3+ in CsCdF3:Gd and CsCaF3:Gd. The parameters for the octahedrally coordinated ligands are rather different from those previously determined from the transferred hyperfine structure of EPR spectra at 300K by Buzare and co-workers (1977). The authors' own EPR measurements show that the separations of the transferred hyperfine-structure lines are rather smaller than those predicted using the ENDOR data. They are only just consistent for CsCdF3, and they are slightly outside the estimated uncertainty of the EPR data for CsCaF3. There is no evidence of temperature dependence of the separation of the transferred hyperfine-structure lines in the EPR spectrum. Local distortions are deduced from 19F second-shell parameters and these distortions and the ligand-shell parameters are compared with those for octahedrally coordinated 19F ligands in CaF2 and CdF2.