Novel Use of Molecular Dynamics Simulation in Studying Structure-Property Relationships in the Solid Infrared Laser Medium Naf-Er3+ /Y-Alumina

X-Ray diffraction studies have been made of the crystalline luminescent material Na+-E$+ p”-alumina for three different erbium ion concentrations; equivalent to 100, 72 and 26% substitution of Na’ ions (Na, +,,-&ErXMgfilll 7, for x = 0.56, 0.40 and 0.1 4, respectively, and y = 2/3). The results form thereafter a structural basis for molecular dynamics (MD) simulations, which, in turn, are used to calculate crystal-field parameters needed for Judd-Ofelt analyses of the optical absorption spectra. The Er3+ ions behave somewhat differently from other rare-earth ions in the Na+ p”-alumina host in that they can occupy two different sites in the conduction plane. Judd-Ofelt intensity parameters are calculated using a point-charge model for different concentrations and temperatures, and agree well with experimentally determined parameters. This agreement is because the local instantaneous distortions around the rare-earth ions are properly accounted for when using atomic positions taken from an MD simulation.