Lamellar, MCM-
41 and MCM-48 periodic porous silicates (SI-) are
obtained under basic conditions by the cooperative
organization of anionic solution silicate species and
cationic surfactant mo1~es.2*9.14,1$16,S1u7c~h a mechanism2
is expected to work for other oxides as well, if the
pH, counterions and solvent are chosen appropriately to
adjust the geometry and charge density of the metal oxide
polyanions in solution balanced against surfactant charge
and packing requirements. Thus, we were able to synthesize
a lamellar tungsten oxide (dlw = 28.3 A) at pH
above 9, and a mixture of the lamellar and a hexagonal
phase (dlw = 40 A) at pH 4-8 using cationic surfactants,
as demonstrated by X-ray diffraction and TEM.Ig