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- Author or Editor: M. Palamaru x
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Abstract
The paper deals with a kinetic study of crystal growth in gelatin and agar gels, using a technique based on radioactive tracers.204TlCl,204TlBr,204TlI,60CoC2O4 and60CoH4C4O6 crystals in gels have been obtained. The global kinetic process of appearance of crystals has been found to be made up of two distinct stages: diffusion of the ions in the gel and crystallization, having different rate constants.
Abstract
This paper presents a radiochemical study of the appearance of204T1I microcrystals and their development as 
disks
resembling Liesegang rings, in gelatin, under different experimental conditions. Thus, kinetic diagrams have been traced, from which gel diffusion rate constants for radioactive ions were calculated, as well as reaction rate constants between reactant species:204T1+ and I–, in colloidal medium, followed by the development of concentrated microcrystals under form of one or more disks. There is an interconnection between gelatin concentration of the colloidal medium, on one hand, and204T1I microcrystal disks number and dimensions, on the other hand, disks which appeared in gel as a result of the global process of nucleation.
Abstract
The paper presents a radiokinetic study on the appearance and growth of*Fe2S3,*Fe(OH)3,*Fe2(C2O4)3,*Fe(IO3)3 crystals in a colloidal medium of agar and gelatine. The values of the diffusion constants through gels of55+59Fe3+ radioactive cations and of the rate of global growth process of these crystals in agar or gelatine were calculated using the experimental data. A new method for the determination of the starting time for the complex nucleation process was proposed. The formation rate of crystals under study decreases in the order:*Fe(OH)3>*Fe(IO3)3>*Fe2S3>*Fe2(C2O4)3, in agar medium and*Fe(OH)3>*Fe(IO3)3>*FeC2O4)3>*FeS3, in gelatine medium.
Abstract
A radiometric method that permits to follow, in real time, the kinetics of crystals growth:134CsClO4;134CsHC4H4O6;134Cs2CrO4;134Cs2[PtCl6] and134Cs[AgI2], in gelatin medium is presented. Constants of the diffusion of134Cs+ radioactive ions through gel and of the reaction between this cation and anions under study, leading to the formation of crystals were calculated. An approximately invesely proportional ratio was found between the rate of nucleation and the solubility of the crystal.
