Precipitation of Calcium Carbonate in Confinement

Abstract

In contrast to the regular morphologies displayed by synthetic single crystals, biogenic single crystals frequently exhibit unusual forms and curved surfaces. Such controlled mineralization in biology occurs within restricted volumes constructed for this purpose and there is significant evidence that some crystals with complex morphologies may form via an amorphous precursor phase. We here investigate morphological control of single crystals, using these biological mechanisms as inspiration. Calcite was precipitated within the cylindrical pores of track‐etch membranes via an amorphous calcium carbonate (ACC) precursor phase. Perfect replication of the pore channel to yield rod‐shaped single crystals of calcite was only achieved when the ACC precursor particles entirely filled the pore channels prior to crystallization, a process dependent on the pore diameter. Misshapen particles were formed in all pore diameters in the absence of an ACC phase. This system provides an ideal opportunity to carry out a systematic study into the effect of pore diameter, and the presence of an ACC precursor phase on crystal growth.

Crystallisation rates of calcite from an amorphous precursor in confinement

“…It will also be seen that our model induces a solid-state ACC-to-calcite transformation as opposed to the dissolution-reprecipitation mechanism observed in, e.g., Ref [7]. The prevalence of such a transformation has yet to be established experimentally but it has been inferred to have occurred both in vivo [3,13,15] and in vitro [16,17].…”

“…Track-etched membranes were identified by Loste and Meldrum [6] to be an ideal system for studying the crystallisation of calcite from ACC in confinement and have since been applied in other studies [7,8]. These experiments involve precipitating amorphous calcium carbonate within cylindrical pores etched into a polycarbonate membrane, with diameters ranging from 50 nm to 10 µm depending on the study.…”

Urease Mediated Synthesis of Crystalline Porous Tin Oxide at Room-temperature and Applications in Lithium-ion Batteries and Gas Sensors

“…The explanation might be following: hydrolyzed tin species continually deposit on the inner surface of large pores, and the confinement effect of pores could assist the phase transformation of amorphous tin oxides. (It was reported that small confinements can altered the reaction kinetics of crystal growth [16] ) During this process, the large pores were gradually filled with newly grew tin oxides, thus, the large pore sizes were diminished to 3.3mn gradually. Since tin oxides have immense potentials as gas sensor and anode material for lithium ion battery, the electrode and sensor performance of urease mediated tin oxides (namely U-SnO 2 ) was tested; for comparison, the performances of porous tin oxides prepared by hydrothermal method (namely H-SnO 2 ) was also tested.…”

Physical Confinement Promoting Formation of Cu2O–Au Heterostructures with Au Nanoparticles Entrapped within Crystalline Cu2O Nanorods

“…[21][22][23][24][25][26][27][28][29] Key outcomes of these works have included the ability to form high aspect ratio nanorods, 23,26 and a route to interface semiconducting transition metal oxide nanowire arrays into macroscale structures with spatial control. 20 Up to this point, reports on electrochemical and solution-based crystallization within the pores of track-etched membranes have involved the formation of single phase or multilayered nanowires.…”