Electron and Nuclear Densities of a Pyrochlore, Y 2 Sn 2 O 7 Studied by the Maximum Entropy Method

Abstract

Electron and nuclear density distributions of the stoichiometric pyrochlore, Y 2 Sn 2 O 7 are obtained by the Maximum Entropy Method (MEM) using synchrotron and neutron powder diffraction data. It is recognized from the MEM electron density distribution that there exist relatively strong covalency between Sn-O(2) atoms to form Sn 2 O 6 sublattice and weak covalency between Y-O(1) atoms to form Y 2 O sublattice. There is no covalent bond linkage between these two sublattices. From the nuclear densities, it is found that the thermal vibrations of Y and Sn atoms parallel to both the Y-O(1) and Sn-O(2) bond directions are rather restricted.