A new modification of ReO₃-type MoO₃ and the deuterated intercalation compound from which it is derived: D_0.99M0O₃

The structures of D_o.₉₉MoO₃ and β′-MoO₃, both closely related to the ReO₃ structure, have been determined from neutron powder diffraction data and refined using the Rietveld technique. D_o.₉₉MoO₃ was prepared by a spillover reaction, and β′-MoO₃, a new modification of MoO₃, by heating this intercalate in oxygen at 200°C, driving off D₂O. The D_o.₉₉MoO₃ structure was refined as cubic (Im3, a = 7.622(1) A ̊) with deuterium statistically occupying two sites. There is evidence of ordering and reduction of the space group symmetry to at least Pm3. The structure of β′-MoO₃ was refined as monoclinic ( P2₁ n, a = 7.4245(1), b = 7.4783(1), c = 7.6897(1) A ̊, β = 90.090(2)°). β′-MoO₃ is isostructural with the room temperature monoclinic modification of WO₃.