Methorics of Precipitation from Electrolytic Solutions as Revealed through Relationship between Concentrational Factors and Kinetics of Solid Phase Formation

For an explanation of the pecularities of precipitating systems they are treated as composed of five subsystems: (i) formation of complex species (simple and monomers, as well as polynuclears and polymers); (ii) embryonation (aggregates without core formation); (iii) nucleation and direct growth (the growing core); (iv) micellation (formation of primary particles with colloid individuality); and (v) secondary structures of micro and macro particles. It is assumed that the transition from ideal liquidus structures (ILS) to ideal solidus structures (ISS) usually proceeds through stages characterized by the development of methorical structures and textures (MS & T). Applying the method of continuous variation of concentration of precipitating components the characteristic four types of precipitation bodies (PB, as a plot of logarithm of concentration of the cationic component against anionic one) are used for description and discussion of experimental results. For illustration some contours of PBs are given (silver bromide; silver salts of fluoresceine group; uranyl phosphates; iron-III hydroxides, thorium hydroxides, hydroxides of lanthanides, all in aqueous solutions). In discussing the morphology of the precipitates obtained by »solution aging« or under the conditions of »homogeneous« precipitation, it was pointed out that the phenomena may be explained by taking into account the role of subsystems and the discontinuities caused by aggregation of submicrons into larger units