A MEAN RADIUS FOR THE FIRST COORDINATION SHELL IN LANTHANIDES

A mean radius R̄ for the first coordination shell of lanthanides in solids is defined in terms of Morrison's local polarizability model, substituting the shifts of the Slater and spin-orbit parameters by their observed phenomenological values. The results obtained agree within 10% with the measured ion-nearest neighbors' distances in rare-earth compounds. We used our definition of a mean radius to predict the average Eu3+-nearest ligand's distance in new luminescent polymer electrolytes. The values found for different concentrations of Eu3+ (2.3-2.7 Å) are compatible with known data for europium. © 1994 American Institute of Physics.