Growth of gypsum III. Influence and incorporation of lanthanide and chromium ions

• Published in: Journal of crystal growth Vol. 144; no. 1; pp. 70 - 78
• Main Authors: de Vreugd, C.H., Witkamp, G.J., van Rosmalen, G.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1994; Elsevier
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Theory and models of film growth; Growth inhibitor; Inorganic compounds; Impurity density; Synthetic mineral; Ternary compounds; Calcium sulfates; Gypsum; Crystal growth from solutions; Supersaturation; Kinetics; Experimental study
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/0022-0248(94)90012-4

The growth of gypsum is retarded by lanthanide ions present in the solution as impurities. The crystal faces show macrostep formation. At relative supersaturations of 0.2 the growth retarding influence of the ions decreases in the order La 3+ ≈ Ce 3+ ≈ Eu 3+ > Er 3+ > Cr 3+ > Cr 2O 2- 7, with a maximal difference of a factor 10 between the blank and La 3+ at a concentration of 3 x 10 -4M. At increasing supersaturations this difference becomes smaller and finally disappears at σ = 1. The uptake of lanthanides increases with increasing ionic radius, with a maximum for Ce 3+. The sequences of growth retardation performance and uptake of the ions are therefore roughly similar. At higher supersaturations the uptake becomes higher. From the growth retardation as a function of the La 3+ concentration an absorption energy of 30 kJ/mol was calculated. From adsorption experiments, no adsorption energy could be derived. The incorporation of Cd 2+ ions in the presence of lanthanides behaves similarly as without these ions.