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The Slow Precipitation of Sparingly‐soluble Metal Salt Powders from Aqueous Solution: Mathematical Relations for the Kinetics of the Crystal Growth Processes in Different Types of Precipitation
Author(s) -
Packter A.
Publication year - 1981
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.2170160710
Subject(s) - precipitation , aqueous solution , diffusion , salt (chemistry) , induction period , metal , crystal growth , growth rate , chemistry , crystal (programming language) , metal ions in aqueous solution , inorganic chemistry , materials science , crystallography , thermodynamics , organic chemistry , mathematics , meteorology , catalysis , physics , geometry , computer science , programming language
The following types of slow precipitation, of sparingly‐soluble metal salts from aqueous solution, have been analysed: precipitations without an induction period – (i) with very few microcrystallites or seeds, (ii) with microcrystallites and first/second order surface or diffusion rate‐controlled growth, (iii) with very many microcrystallites; precipitations with significant induction periods – (i) with very few microcrystallites or seeds, (ii) with microcrystallites and first/second order surface or diffusion rate‐controlled growth, (iii) with very many microcrystallites. Generally, in the early stages of precipitation, growth rates depend on the rate of addition of metal salt ions to the system and on the rate constant for crystal growth; in this stage, rates increase from low values to optimum values: in the later stages of precipitation, the metal salt ions are used up as rapidly as they are added to the system and growth rates then depend only on the rate of addition and on the number of microcrystallites or seeds; in this range, rates gradually decrease to low values. Mathematical relations, for the variation of crystal size with precipitation time at different stages of growth, have been derived for each of the above types of precipitation.