J. Rocha et al., SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF MICROPOROUS YTTRIUM AND CALCIUM SILICATES, JOURNAL OF PHYSICAL CHEMISTRY B, 102(24), 1998, pp. 4739-4744
The synthesis and structural characterization of AV-1 (Aveiro micropor
ous solid no. 1), the first synthetic microporous yttrium silicate con
taining stoichiometric amounts of framework sodium (and yttrium) catio
ns, are reported. AV-1, Na2K2Y2Si16O38. 10H(2)O, possesses the structu
re of the rare mineral montregianite. The synthesis and structural cha
racterization of AV-2, an alkali calcium silicate hydrate (ideal compo
sition HKCa2Si8O19.6H2O) analogue of the rare mineral rhodesite, are a
lso reported. The structures of AV-1 and AV-2 are characterized by the
same type of double silicate layers, but important differences exist
with respect to the constitution of the octahedral layers and channel
species. AV materials have been characterized by a range of techniques
, viz., scanning electron microscopy (SEM), powder X-ray diffraction (
XRD), Si-29 and Na-23 single- and triple-quantum (3Q) magic-angle spin
ning (MAS) NMR spectroscopy, Fourier transform spectroscopy (FTIR), an
d thermogravimetric analysis (TGA).