Structural trends in Bi containing pyrochlores: The structure of Bi2Rh2O7 − δ

The room temperature structure of Bi2Rh2O7 − δ has been refined from neutron powder diffraction data, λ = 1.8857 Å, cubic Fd 3̄m, a = 10.2763(1) Å, V = 1085.23 Å3, Z = 8, Rp = 0.040, Rwp = 0.054, Rexp = 0.035 for 45 reflections. The structure is of a pyrochlore type with the oxygen position parameter of 0.3317(4) where there are both bismuth and oxygen vacancies. The anion vacancies are in the 8b O′ site. The structure is compared with that of a number of other Bi containing pyrochlores.