Atomic force microscopy investigation of the mechanism of calcite microcrystal growth under Kitano conditions

A combined atomic force microscopy (AFM)-inverted optical microscopy technique has been used to image the surface of calcite single microcrystals, with dimensions of 10-20 microm, at high resolution. The microcrystals were grown on a glass substrate using the Kitano method, a process that involves the outgassing of carbon dioxide from a saturated solution of calcium carbonate. The resulting increase in the supersaturation of the solution, with respect to calcium carbonate, induces crystallization. It is demonstrated, for the first time, that calcite microcrystals formed in this way exhibit a single spiral growth hillock on the (104) surface, as evidenced by a spiral step pattern, indicating that growth occurs at steps arising from an individual screw dislocation. The subsequent reactivity of these crystals under Kitano conditions has been followed in situ using AFM imaging.