MOLECULAR-DYNAMICS-BASED ANALYSIS OF THE ABSORPTION-SPECTRA OF ND3-DOPED NA+ BETA''-ALUMINA( )

The polarized absorption spectra of Nd3+-doped Na+ beta''-alumina have been treated theoretically for five neodymium concentrations. The per turbing crystal field, needed in the Judd-Ofelt analysis, is calculate d from a molecular-dynamics simulation for each composition. Oscillato r strengths and Judd-Ofelt intensity parameters are calculated using a point-charge model at each time step in the simulation for each of th e Nd3+ ions in the simulation box. A study of the effect of the dynami cs of the system on these parameters was also made. The theoretical re sults thus obtained are compared to experiment. It is shown that the a bsorption spectra can be explained essentially on the basis of the spe cial structural situation of the Nd3+ ions in these materials.