Crystal growth in nanoconfinement

Orateur : Dag Kristian DYSTHE (University of Oslo / LIPhy)

In setting cements, in porous rocks, in building stones and in concrete, changes in fluid composition may cause crystal growth in the pore space. Such crystal growth may have two opposite effe cts on the material : the crystallizing phase may create more cohesive grain contacts and strengthen the material or it may force grains apart and fracture and weaken the material. Except for a general equilibrium thermodynamic argument for the limit to the force of crystallization there exists no experimental data or theoretical models to understand the transition from crystallization force to cementation. We study crystallization in nanoconfinement : in the nanometer thin fluid films at the contact between a growing crystal and another solid. High degree of control of supersaturation combined with high resolution imaging of the nanoconfined growing crystal surface has allowed us to study details of the crystallization process and stress buildup. I will present recent results for two brittle, non-hydrated crystals : the highly soluble sodium chlorate (NaClO3) and the sparingly soluble calcite (CaCO3). I will demonstrate the basic mechanisms of nanoconfined crystal growth, (surprising) growth instabilities and the limits to growth.

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