High-resolution total neutron scattering, in conjunction with reverse Monte Carlo simulations, were used to examine the crystal structure of this vacancy-ordered oxide pyrochlore, Pb2Ru2O6O0.5, by analogy to proton ordering in the structures of ice. It was found that the vacancy and the O' ion were completely ordered, and that the average structure in the F¯43m space group described the vacancy ordering precisely. These results were complemented by an examination of the Pb2+ lone pair network using density functional electronic structure calculations, and acomparison of the low-temperature lattice-only heat capacity of Pb2Ru2O6O0.5' with that of other related pyrochlores.

Reverse Monte Carlo Neutron Scattering Study of the 'Ordered-Ice' Oxide Pyrochlore Pb2Ru2O6.5. D.P.Shoemaker, A.Llobet, M.Tachibana, R.Seshadri: Journal of Physics - Condensed Matter, 2011, 23[31], 315404