Electron and nuclear densities of a pyrochlore, Y2Sn2O7 studied by the maximum entropy method

Electron and nuclear density distributions of the stoichiometric pyrochlore , Y2Sn2O7 are obtained by the Maximum Entropy Method (MEM) using synchrotro n and neutron powder diffraction data. It is recognized from the MEM electr on density distribution that there exist relatively strong covalency betwee n Sn-0(2) atoms to form Sn2O6 sublattice and weak covalency between Y-O(1) atoms to form Y2O sublattice. There is no covalent bond linkage between the se two sublattices. From the nuclear densities, it is found that the therma l vibrations of Y and Sn atoms parallel to both the Y-O(1) and Sn-O(2) bond directions are rather restricted.