Laser spectroscopy of defect chemistry in CaF2:Er3+

Abstract

Alkaline earth fluoride crystals doped with trivalent lanthanide ions have been studied as model systems for the solid state defect equilibria important in all solids. Problems have arisen in these systems because the behavior does not agree qualitatively with the expected behavior. Most explanations attribute the problems to competing defect equilibria which were previously not considered. In this paper, we have measured the concentrations of all the lanthanide defect sites as a function of both annealing temperature and dopant concentration. Clusters are seen to be an important part of these defect equilibria and could be contributing competing equilibria. At high annealing temperatures, however, the site distribution simplifies so there can be no competing equilibria and yet the anomalous behavior remains. Nonideality effects must be responsible for this behavior.