reported the crystal structure of montgomeryite.
It is monoclinic with space group (C2/c), (a = 10.023(1),
b = 24.121(3), c = 6.243(1)A˚ ), ˇ 91.55(1)◦, clusters per unit cell Z = 2.
The structure consists of chains of corner-linked octahedral (AlO6)
clusters which are topological and geometrically equivalent to
the chains in vauxite, Fe2
2+(H2O)4[Al4(OH)4(H2O)4(PO4)4]·4H2O.
According to Moore and Araki [4] the (AlO6) octahedra are
linked by the (OH)-ligands and are alternatively in cis- and
trans-configurations. The octahedral (AlO6) clusters octahedral
chain and associated tetrahedral (PO4) clusters can be written as
[Al4(OH)4(PO4)6]10−; for vauxite, it is [Al4(OH)4(H2O)4(PO4)4]4−.
These units are proposed to be underlying features of the 2 structures
with the more weakly bonded cations intercalated in the
remaining spaces. In montgomeryite, the (PO4) tetrahedra bridge to
equivalent chains along the c-axis, forming slabs parallel to
{0 1 0},
which is the direction of perfect cleavage. The Mg atoms are disordered
and occupy only half of its available sites.
reported the crystal structure of montgomeryite.It is monoclinic with space group (C2/c), (a = 10.023(1),b = 24.121(3), c = 6.243(1)A˚ ), ˇ 91.55(1)◦, clusters per unit cell Z = 2.The structure consists of chains of corner-linked octahedral (AlO6)clusters which are topological and geometrically equivalent tothe chains in vauxite, Fe22+(H2O)4[Al4(OH)4(H2O)4(PO4)4]·4H2O.According to Moore and Araki [4] the (AlO6) octahedra arelinked by the (OH)-ligands and are alternatively in cis- andtrans-configurations. The octahedral (AlO6) clusters octahedralchain and associated tetrahedral (PO4) clusters can be written as[Al4(OH)4(PO4)6]10−; for vauxite, it is [Al4(OH)4(H2O)4(PO4)4]4−.These units are proposed to be underlying features of the 2 structureswith the more weakly bonded cations intercalated in theremaining spaces. In montgomeryite, the (PO4) tetrahedra bridge toequivalent chains along the c-axis, forming slabs parallel to{0 1 0},which is the direction of perfect cleavage. The Mg atoms are disorderedand occupy only half of its available sites.
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