Pulsed Neutron Diffraction Studies on Lanthanide(III)Hydration in Aqueous Perchlorate Solutions

Abstract

AbstractPulsed neutron diffraction measurements are reported on 2 molar aqueous solutions of Pr3 + , Nd3 + , Tb3 + , Dy3 + , Tm3 + , and Yb3+ in D2O at room temperature. The first order difference technique on isomorphous ions is used to derive the metal ion pair correlation functions in these systems. The metal-oxygen and metal-deuterium distances and the hydration numbers are determined. The data indicate that the hydration number changes from ~ 10 for the lighter ions to ~8 for the heavier ones in the series. The water dipole is orientated on the average at an angle of 10 ~ 20 degrees to the metal-oxygen vector; these values are significantly smaller than those found for mono- and di-valent ions. The present results are compared with other results from neutron diffraction with isotope substitution, X-ray diffraction, and extended X-ray absorption fine structure.