The solid solution (Fe0.81Al0.19)(H2PO4)3 with a strong hydrogen bond

Single crystals of the solid solution iron aluminium tris(dihydrogenphosphate), (Fe_0.81Al_0.19)(H₂PO₄)₃, have been prepared under hydrothermal conditions. The compound is a new monoclinic variety (γ‐form) of iron aluminium phosphate (Fe,Al)(H₂PO₄)₃. The structure is based on a two‐dimensional framework of distorted corner‐sharing MO₆ (M = Fe, Al) polyhedra sharing corners with PO₄ tetrahedra. Strong hydrogen bonds between the OH groups of the H₂PO₄ tetrahedra and the O atoms help to consolidate the crystal structure.