Crystal structures of paraelastic aluminum molybdate and ferric molybdate, β-Al2(MoO4)3 and β-Fe2(MoO4)3

The high-temperature crystal structures of β-Al(MoO4)3 and β-Fe2(MoO4)3, as determined by Rietveld refinements against time-of-flight neutron powder data, are described. Both phases crystallize in the orthorhombic scandium tungstate [Sc2(WO4)3] structure and consist of MO6 (M = Al, Fe) and MoO4 building blocks, fused together via MOMo bonds. Both materials have rearranged from their room-temperature monoclinic structures.