FTIR AND MOSSBAUER INVESTIGATION OF A SUBSTITUTED PALYGORSKITE - SILICATE WITH A CHANNEL STRUCTURE

Crystal data and spectroscopic studies of a silicate with a channel st ructure 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 compoun d 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-ce ll parameters were determined using X-ray diffraction: a = 12.7 Angstr om, b = 17.9 Angstrom, c = 5.2 Angstrom, beta = 91.86 degrees. The Mos sbauer results proved that the very small amount of Fe(III) ions subst ituting Mg in the sample are located at two structural sites in the la ttice. Through the FTIR spectrum analysis a more reliable assignment w as performed with respect to tetrahedra, octahedra, hydroxyl groups an d water molecules. (C) 1997 Elsevier Science Ltd. All rights reserved.