Hydrolysis of molybdenum and tungsten alkoxides: sols, powders and films

• Published in: Journal of non-crystalline solids 1990, Vol.124 (2), p.155-166
• Main Authors: Yanovskaya, M.I, Obvintseva, I.E, Kessler, V.G, Galyamov, B.Sh, Kucheiko, S.I, Shifrina, R.R, Turova, N.Ya
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/0022-3093(90)90258-N

Hydrolysis of molybdenum and tungsten alkoxides of the two series MO(OEt) 4 and MO 2(OEt) 2 (M = Mo, W) has been studied. Hydrolysis products and the partially hydrolyzed solutions have been characterized by means of X-ray diffraction, IR, electron spectroscopy and small-angle X-ray scattering. Preparation of stable sols is reported and their structures are discussed in terms of a fractal model. While ‘tungsten solutions’ may be described as typical polymeric sols, ‘molybdenum solutions’ should be regarded as particulate sols. The reason for this difference has its origin in the structures of alkoxides and mechanisms of their hydrolysis. Sols were used for the preparation of electrochromic and photochromic films by spin-coating techniques. A coloration mechanism is discussed in terms of the percolation model. Some properties of the composite structures WO 3TiO 2, n-SiWO 3 are also reported.