Ligand hyperfine structure of EPR spectra of [Eu.sup.2+] ions in superionic Ca[F.sub.2] crystals

The electron paramagnetic resonance (EPR) spectra of the [Eu.sup.2+] ion in Ca[F.sub.2] crystals is investigated. In samples with [Eu.sup.2+] concentration equal to 0.1 and 0.01 mole %, additional splitting of the hyperfine structure lines is observed. The electron paramagnetic resonance spectrum is calculated with allowance for the ligand hyperfine interactions (LHFI), and the resulting line shape of the hyperfine structure is determined for the central finestructure transition. Comparing the calculated spectrum with the experimental one, we have determined the principal values of the LHFI tensor [T.sub.∥] = 18.44 MHz and Tj_ = -12.98 MHz and have carried out a comparative analysis of the values obtained with the results of other authors. Using nonlinear least squares fitting, we have determined the parameters of the partially resolved lines in the spectra. Keywords: solid electrolytes, superionic crystals, crystal field, spin Hamiltonian, EPR, fluorite, europium, defects.