The local field distribution of in transition metal fluoride glasses investigated by electron paramagnetic resonance

Publisher Website
Google Scholar
Abstract
The EPR spectra of in two transition metal fluoride glasses (PZG and PBI) have been extensively studied as functions of temperature, concentration and microwave frequency (S, X, K and Q bands). The marked changes observed in the EPR spectra with temperature and concentration imply the existence of pairs of ions. The spectra of isolated ions were obtained at low temperature for samples with low doping concentration. Isolated ions are characterized by a fine-structure -parameter distribution within the range . The simulations of these spectra are computed with a Czjzek fine-structure parameter distribution (this solution prohibits the existence of axial symmetry sites). It indicates a decrease of the number of geometrical constraints compared to those for and (octahedral coordination in a fluoride medium), in agreement with the higher coordination numbers. -ion sites are found to be more distorted in PZG than in PBI, suggesting that the glass network has an influence on the polyhedron distortion amplitude.