Exploring the role of crystal habit in the Ostwald rule of stages.

ABSTRACT: The crystallization of calcium carbonate is shown to be dictated by the Ostwald rule of stages (ORS), for high relative initial supersaturations ( SCaCO3=[Ca2+][CO32-]/KSP, Calcite>2500 ), under sweet (carbon dioxide saturated) and anoxic (oxygen depleted) solution conditions. Rhombohedral calcite crystals emerge after the sequential crystallization and dissolution of the metastable polymorphs: vaterite (snowflake-shaped) and aragonite (needle-shaped). However, the presence of certain cations, which can form trigonal carbonates (e.g. Fe²⁺ and Ni²⁺), in concentrations as low as 1.5 mM, triggers the emergence of calcite crystals, with a star-shaped crystal habit, first. These star-shaped crystals dissolve to yield needle-shaped aragonite crystals, which in turn dissolve

SUBMITTER: Hadjittofis E 

PROVIDER: S-EPMC8826364 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature