ELECTRO-OPTICAL STUDY OF OXIDE DISPERSIONS AND THEIR STABILIT

Oxide/solution interface is with the clear origin of the surface charge, obtained through ionization of surface hydroxyl groups. The oxide particles produced by flame hydrolysis present fractal aggregates built from nearly spherical particles with constant diameter (AI₂O₃, SiO₂). In the process of acid hydrolysis particles with well defined form (spheres, rods, ellipsoids) and high monodispersity could be obtained (α-Fe₂O₃, α-β-FeOOH). Different types of oxides are investigated by the means of electric light scattering. An information on the electric surface properties of oxide/solution interface as well as in presence of various additives, particles dimensions and fractal structure is obtained. The process of slow coagulation in presence of bivalent electrolyte and surface active substance is studied electrooptically. The change of dynamic electric behaviour (induced dipole moment) in the processes of interaction is followed. Some considerations are made on the nonequillbium electric properties of the interface and the connection with suspension stability.