Effect of surface orientation on dissolution rates and topography of CaF2

Mechanisms influencing micron and nanometer-scale reaction rate patterns during dolostone dissolution

“…8e) reveals several important features. First, three of the curves have bimodal peaks (Δt 01 , Δt 12 , and Δt 34 ), which could be due to different crystallographic orientations in the two adjacent crystals (e.g., Godinho et al, 2012). While apparent in these "snapshot" spectra, the contrast between the two grains -which can be seen to be separated by a clear grain boundary -becomes more pronounced when examining the height changes over longer periods of time ( Fig.…”

Simulation of surface dynamics during dissolution as a function of the surface orientation: Implications for non-constant dissolution rates

“…The numerical model described here is based conceptually on the general model for dissolution of polycrystalline materials presented in Godinho et al (2012Godinho et al ( , 2014a. This model is based on experimental results which showed that, during dissolution of fluorite, stable surfaces tend to persist, and high energy sites, such as steps, are progressively removed (Godinho et al, 2012).…”

“…This model is based on experimental results which showed that, during dissolution of fluorite, stable surfaces tend to persist, and high energy sites, such as steps, are progressively removed (Godinho et al, 2012). The preferential release of atoms from less stable sites exposes more stable surfaces, causing systematic changes of topography and the progressive stabilization of the surface.…”

“…This is followed by the release of the surface atoms or clusters into solution, and consequent change of the surface structure where the atoms were released. The preferential dissolution of kink sites relative to steps and of steps relative to terraces makes dissolution a dynamic process that continuously changes the surface in terms of area and reactivity (Fischer et al, 2012;Godinho et al, 2012Godinho et al, , 2014aLasaga and Lüttge, 2001;Lüttge, 2005). This suggests that the traditional method of calculating dissolution rates normalized to an overall surface area (Brantley et al, 2008;Lasaga, 1981;Oelkers and Schott, 2009) should result in a variation of dissolution rates with dissolution time.…”

“…In the presented model, we simulate the development of topography on a two dimensional profile over fluorite surfaces with different orientations and test its validity by comparison with experimental results. The novelty of this simulation approach is that the governing equations used to calculate the local dissolution rates were determined experimentally (Godinho et al, 2012) and only dependent on the orientation of a surface. Our results show that the dissolution rate of a mineral phase cannot be a single value for a specific dissolution condition (e.g.…”