EPR STUDY OF NI-3+ CENTERS IN CSCAF3

The EPR spectra of Ni3+ ions created by RT X-irradiation of CsCaF3 have been measured at 15 K. They can be described by an isotropic Zeeman term with an effective S=1/2 and g=4.183 and the superhyperfine structure corresponding to the interaction with the six nearest neighbour fluorines. The values of the superhyperfine parameters are A(parallel-to) = 141x10(-4) cm-1 and A(perpendicular-to)=18X10(-4) cm-1. From the isotropic part of these superhyperfine parameters we have estimated the distance between the central ion and the ligands. The value obtained has been compared with the results for Ni3+ in other isostructural fluoroperovskites.