FTIR and Mossbauer investigation of a substituted palygorskite: Silicate with a channel structure

Crystal data and spectroscopic studies of a silicate with a channel structure were realized. The substituted palygorskite from Las Quijadas (San Luis), Argentina, was studied by X-ray S-BET, FTIR and Mossbauer spectroscopy. X-ray results clearly show that the investigated compound crystallizes in a monoclinic structure with space group C-2/m (C-2h(3), No. 12), and Z = 2. It is aluminium-rich and dioctahedral. Unit-cell parameters were determined using X-ray diffraction: a = 12.7 Angstrom, b = 17.9 Angstrom, c = 5.2 Angstrom, beta = 91.86 degrees. The Mossbauer results proved that the very small amount of Fe(III) ions substituting Mg in the sample are located at two structural sites in the lattice. Through the FTIR spectrum analysis a more reliable assignment was performed with respect to tetrahedra, octahedra, hydroxyl groups and water molecules. (C) 1997 Elsevier Science Ltd. All rights reserved.