Toward pillared metal sulfides:: Encapsulation and Rietveld structural characterization of the Al13O4(OH)24(H2O)127+ cluster into MoS2 and WS2

The synthesis of [Al13O4(OH)(24)(H2O)(12)](x)MS2 (x = 0.02-0.05, M = Mo; x = 0.02-0.055, M = W) was accomplished by a precipitative encapsulation technique using single layers of MS2. The products were characterized by powder X-ray diffraction, energy dispersive spectroscopy (EDS), thermal gravimetric analysis (TGA), Al-27 MAS-NMR, room temperature electrical conductivity measurements, and surface area measurements. Powder X-ray diffraction patterns show ism expansion of approximately 9.9 Angstrom Al-27 MAS-NMR indicates that the cluster is intact between the MS2 layers. One-dimensional electron density mapping and Rietveld refinement performed on the powder diffraction data show that the cluster is oriented with its C-3 symmetry axis perpendicular to the layers, The samples exhibit conductivity values from 3 to 14 S/cm, TGA shows that the cluster is completely stable to 100 degrees C, and largely stable to 330 degrees C, Surface area measurements suggest that the space between the clusters is not accessible. (C) 1998 Academic Press.