EPR STUDY OF NI-3+ CENTERS IN CSCAF3

The EPR spectra of Ni3+ ions created by RT X-irradiation of CsCaF3 hav e 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 struct ure corresponding to the interaction with the six nearest neighbour fl uorines. The values of the superhyperfine parameters are A(parallel-to ) = 141x10(-4) cm-1 and A(perpendicular-to)=18X10(-4) cm-1. From the i sotropic 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 flu oroperovskites.