Optical Property and Local Environment of Ni 2+ in Fluoride Glasses

Optical absorption and extended X-ray absorption fine structure (EXAFS) spectra were measured on series of ZrF 4 −BaF 2 −LaF 3, ZrF 4 −BaF 2 −MF−LaF 3 (M; Li, Na, K, Rb, or Cs) and AlF 3 −BaF 2 −CaF 2 −YF 3 glasses doped with Ni 2+ . The optical absorption spectra show that Ni 2+ ions in all the glasses exist in octahedral coordination sites with six F - ions. The values of ligand field strength, 10 Dq, were obtained from the optical absorption spectra, and Ni−F interatomic distances, r Ni-F, were determined by EXAFS analyses. The linear relationship between 10 Dq and r Ni-F is found and interpreted by simple ligand field theory. The compositional dependence of the 10 Dq and r Ni-F is discussed in terms of the basicity of glasses. We discuss the optical property and the local environment of Ni 2+ in the fluoride glasses in comparison with those of oxide glasses.