Premium
The precipitation of barium chromate powders from aqueous solution at different pHs: Nucleation, final crystal numbers and sizes
Author(s) -
Packter A.,
Alleem 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.19810160108
Subject(s) - nucleation , precipitation , aqueous solution , crystal (programming language) , metal , salt (chemistry) , chemistry , barium , homogeneous , inorganic chemistry , crystallography , materials science , mineralogy , thermodynamics , organic chemistry , meteorology , physics , computer science , programming language
Barium chromate precipitations were studied from equivalent aqueous solutions of initial overall metal salt concentrations from 0.00013 to 0.010 M at ambient temperature and at p Hs from 8 to 3. At p Hs from 8 to 5, precipitation mainly occurred through homogeneous nucleation: the reciprocal induction periods (and nucleation rates) and the crystal numbers generally decreased with reduction of p H but the values at any effective mean metal salt concentration increased appreciably with increasing acidity. Presumably, both M ++ A and M ++ HA − species were taking part in the nucleation process. – At p Hs below 5, heterogeneous nucleation predominated in most precipitations: the crystal numbers and nucleus numbers at any effective metal salt concentration increased with reduction of p H in these systems. Presumably, more active sites for heterogeneous nucleation were developed.