The Effect of Additives on the Early Stages of Growth of Calcite Single Crystals

Abstract

As crystallization processes are often rapid, it can be difficult to monitor their growth mechanisms. In this study, we made use of the fact that crystallization proceeds more slowly in small volumes than in bulk solution to investigate the effects of the soluble additives Mg2+ and poly(styrene sulfonate) (PSS) on the early stages of growth of calcite crystals. Using a “Crystal Hotel” microfluidic device to provide well‐defined, nanoliter volumes, we observed that calcite crystals form via an amorphous precursor phase. Surprisingly, the first calcite crystals formed are perfect rhombohedra, and the soluble additives have no influence on the morphology until the crystals reach sizes of 0.1–0.5 μm for Mg2+ and 1–2 μm for PSS. The crystals then continue to grow to develop morphologies characteristic of these additives. These results can be rationalized by considering additive binding to kink sites, which is consistent with crystal growth by a classical mechanism.

Microfluidic Control of Nucleation and Growth of CaCO3

“…Studies in nucleation and growth of CaCO 3 polymorphs in microfluidics are mainly intended to cast light on fundamental aspects of inorganic CaCO 3 crystallization pathways [37][38][39] or biomimetic or biomineralization processes. [40][41][42][43][44][45][46][47][48][49] Zeng et al 39 used microfluidics to control the formation of ACC and transformation pathways to vaterite and calcite, Li et al 38 also studied crystallization pathways but included the use of FTIR in microfluidics and Rodriguez-Ruiz 37 studied how confinement in microfluidic reactors stabilized the hydrated CaCO 3 mineral ikaite. Yashina et al 45 used ex situ SEM to study nucleation and initial growth of CaCO 3 polymorphs formed by mixing Na 2 CO 3 and CaCl 2 in microfluidic droplets, Gong et al, 47 used a gas-liquid microfluidic system to study growth of calcite crystals around obstacles and Kim et al 49 used a similar system to study early stages of CaCO 3 growth in presence of additives.…”

Acidic monosaccharides become incorporated into calcite single crystals

“…Interestingly in this case negligible lattice distortions were detected (see Figure S5 and table S1). This emphasizes the importance of the acidic group in facilitating incorporation of MSs into the lattice of calcite probably via the carboxylate group substituting the carbonate group [74] or interacting with calcium ions. Annealing of the samples caused significant broadening of the diffraction peaks and relaxation of the lattice distortions, as shown by the shift in diffraction peaks towards the position of the control calcite sample (Figure 3).…”

Time‐Resolved Dynamics of Struvite Crystallization: Insights from the Macroscopic to Molecular Scale

“…Microfluidics is most commonly used as am icrobatch system in the form of dropletm icrofluidics to monitor crystal nucleation and growth in nanoliterv olumes. [48][49][50][51][52] To our knowledge, few crystalline materials have been studied in microfluidic devices under continuousf low of ag rowth medium. [38,39,53,54] In this study,w eu sed am odified design of an established microfluidics platform [53] for measurements of struvitec rystallization.…”