Original title: Viscoelastic interfacial structures in undersaturated calcium solutions under nanoconfinement
Shurui Miao, Timothy S. Groves, Kieran J. Agg, Susan Perkin · August 2026
Minerals like calcium carbonate grow in bones, shells, and carbon storage sites. Scientists still do not fully understand how these minerals first start to form. To explore this, researchers squeezed calcium solutions into tiny, nanometer-scale spaces. The liquid was undersaturatedThe solution contains fewer dissolved calcium and carbonate ions than needed to form solid crystals., meaning it did not have enough calcium to form solid crystals normally. They used sensitive tools to measure the forces between the surfaces. They discovered that calcium ions link up with water at the mineral surface. This creates a flexible, gel-like network that pushes the surfaces apart. This springy network stays stable across a wide range of acidity, but other competing ions can break it up. Even without enough dissolved mineral to form solids, surfaces and tight spaces help build these early structures.
Imagine you are trying to build a sandcastle on a beach. The sand is damp enough to hold shape, but you are not adding any extra water. Normally, the sand grains just sit loosely and collapse easily. But if you pack the sand into a small mold, the grains suddenly stick together and form a stable structure, even though there is no extra water. In this paper, calcium ions are like the sand grains, and the narrow space between two surfaces acts like the mold. The ions organize into a stable network without forming crystals, just as the sand holds together without turning into solid rock.
This work reveals that calcium ions can organize into stable networks before crystals form, challenging the assumption that crystallization only starts from random collisions. For fields like carbon storage and biomineralization, this means we may be able to design environments that promote or prevent nucleation by controlling interfaces and confinement. Understanding these early steps could lead to more efficient carbon mineralization or better synthetic bone materials.
The abstract doesn't explicitly state limitations, but the study focuses on calcium solutions under nanoconfinement and undersaturated conditions, so the findings may not generalize to other ions or bulk conditions. The networks are inferred from force measurements, not directly observed, and their exact structure remains unresolved.
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Viscoelastic interfacial structures in undersaturated calcium solutions under nanoconfinement — Shurui Miao, Timothy S. Groves, Kieran J. Agg et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.