Transition Metal Oxide Gels and Colloids

Abstract

Gels and colloids are very widespread in nature. The familiar dessert jelly, the vitreous humor that fills the interior of the eye, marmalade, clays, india ink, milk, and blood serum are gels or colloids. They are also important intermediates in the manufacture of rubber and plastics, and are used in the laboratory for chromatography and electrophoresis. Gels and colloids have been studied for more than a century, and Graham (1861) is usually regarded as the founder of colloid science. Nevertheless, most of the physical chemistry of gels has been developed only during the last 40 years, mainly by Flory at Stanford University (1). These studies deal mostly with organic polymers. There is much less work on inorganic compounds (2) and, to our knowledge, this paper is the first attempt to review transition metal oxide gels and colloids. In that field, most of the work has been done by French groups during the last four years. The uniqueness of this work lies in its considering transition metal oxide gels as new materials having specific physical properties. A gel being a form of matter intermediate between liquid and solid, its electrical, optical, or magnetic properties could lead to new applications in the field of materials SCIence.