An Atomic Force Microscopy Study of the Growth of a Calcite Surface as a Function of Calcium/Total Carbonate Concentration Ratio in Solution at Constant Supersaturation

Abstract

Calcite growth experiments using atomic force microscopy (AFM) were conducted at two constant values of supersaturation (Ω 1 = 5.248 and Ω 2 = 6.457) while varying the Ca 2þ to CO 3 2concentration ratio. The calcite growth rate and the morphology of growth depend on the solution stoichiometry. At a constant degree of supersaturation, the growth rate was highest when the cation/total carbonate anion ratio, r*, was equal to 1 but decreased nonsymmetrically for higher or lower values of r*. The observed dependence of growth rates on solution stoichiometry can be explained by nonequivalent attachment frequencies of cation and anion at ratios that differ from 1. At the same time, the morphology of the closing etch pits and of the forming nuclei was different when the rate changed, suggesting a change in the crystal growth mechanism.

Phase and morphology evolution of calcium carbonate precipitated by carbonation of hydrated lime

“…]/[CO 3 2-] [ 1). Note that Nehrke et al [77] and Tai et al [78] have shown that the growth rate of calcite is significantly reduced as the growth solution departs from stoichiometry, while in situ AFM observations by Perdikouri et al [79] show that the rate of step propagation across 10 " 14 f g calcite faces is strongly reduced when [Ca 2? ]/[CO 3 2-] [ 1.…”

Calcite growth kinetics: Modeling the effect of solution stoichiometry

“…However, until recently the dependence of calcite growth rates on the solution stoichiometry has received limited attention (Tai et al, 2005;Nehrke et al, 2007;Perdikouri et al, 2009;Larsen et al, 2010;Stack and Grantham, 2010). This is remarkable given that (a) the compositions of most natural waters are highly non-stoichiometric with respect to calcium carbonate, and (b) a large body of work has shown that growth and dissolution rates of ionic minerals are markedly affected by the anion to cation concentration ratio in solution (Davies and Jones, 1955;Davies and Nancollas, 1955;Christoffersen and Christoffersen, 1979;Stubičar et al, 1990;Devenyns, 1990, 1992;Zhang and Nancollas, 1992;Burke and Nancollas, 1999;Rashkovich et al, 2006;Kowacz et al, 2007).…”

Growth Rate and Morphology of a Single Calcium Carbonate Crystal on Polysulfone Film Measured with Time Lapse Raman Micro Spectroscopy

“…The growth rate depends on solution parameters, such as: the supersaturation index (SI), the ionic strength (I), the pH and the [Ca 2+ ]/[CO 3 2-] ratio [8,[32][33][34][35]. Table 1 compares the results from this study with results from the literature [33][34][35].…”

“…Table 1 compares the results from this study with results from the literature [33][34][35]. Experimental conditions for crystal growth rates vary widely in the literature and importantly influence observed growth rates.…”