Nanoscale kinetics of amorphous calcium carbonate precipitation in H₂O and D₂O

Abstract

Calcium carbonate (CaCO3) is one of the most well-studied and abundant natural materials on Earth. Crystallisation of CaCO3 is often observed to proceed via an amorphous calcium carbonate (ACC) phase,...

Hybrid scanning electrochemical cell microscopy-interference reflection microscopy (SECCM-IRM): tracking phase formation on surfaces in small volumes

“…We applied the reactivetransport model we previously reported for time-dependent CaCO 3 (aq) speciation. 21 Simulation details are further described in the FEM results section below. during the experiments, while the ITO substrate (WE) was held at a virtual ground.…”

“…[14][15][16][17] Electrochemical techniques can be used to change solution composition in a controlled manner, by either consuming/producing reagents at the surface of an electrode immersed in a solution, [18][19][20] or by precisely mixing reagents using migration and electroosmotic flow in a nanopipette. [21][22][23][24] A particular advantage of electrochemistry is that the driving force can usually be controlled via the applied potential and mass transport can be varied over a wide range, and modelled with a high degree of accuracy, [25][26][27] allowing spatiotemporal changes in solution composition to be predicted quantitatively.…”

Visualization of Ion Fluxes in Nanopipettes: Detection and Analysis of Electro-osmosis of the Second Kind

“…This ability to manipulate ion fluxes has been demonstrated to great effect in the study of crystal nucleation and growth, where conditions can be created where a solid phase forms inside the nanopore as the filling solution becomes saturated with respect to the target solute. 1,12,2,3,13 The current response during precipitation can be analyzed to reveal, for example, the induction time, 13 the size of the nucleated particle, 14 and even particle charge. 15 To use the applied potential to control reaction conditions within a nanopore, it is essential that the local electric field and ion distribution are understood.…”

“…15 To use the applied potential to control reaction conditions within a nanopore, it is essential that the local electric field and ion distribution are understood. Most understanding in this area comes from finite element method (FEM) simulation of the continuum Poisson−Nernst−Planck model, 1,3,4,13,16 with the Navier−Stokes equation also added to account for electroosmotic flow (EOF) 17 and speciation reactions to account for solution equilibria. 16 While providing significant insight, these models also make a number of assumptions that have not yet been tested adequately.…”

“…In principle, this field can then be used to accumulate or deplete ionic species within the pore, providing a fascinating way of controlling the composition of microscopic regions of solution. This ability to manipulate ion fluxes has been demonstrated to great effect in the study of crystal nucleation and growth, where conditions can be created where a solid phase forms inside the nanopore as the filling solution becomes saturated with respect to the target solute. ,,,, The current response during precipitation can be analyzed to reveal, for example, the induction time, the size of the nucleated particle, and even particle charge …”