Mg < Sup > 2 + < / Sup >, K < Sup > + < / Sup > Synergy Below The Growth Of Crystals

In this dissertation, we synthesized a series of calcium carbonate crystals via hydrothermal method and CO2-diffusion method. Morphologies of calcium carbonate crystals were successfully synthesized by adding Mg2+and K+in the system. The effects of the difference synthetic conditions on the shape, structure and phase composition were studied systematically. The possible formation mechanisms were discussed. The main research fruit obtained are summed up as following:1. Calcium dodecyl sulfate (CDS) was used as an anionic surfactant and the source of calcium in the precipitation process of calcium carbonate (CaCO3) crystals. Tube-shaped aragonite was fabricated, in which Mg2+and K+was added as additives. The cooperative effect of CDS, Mg2+and K+was crucial in fabricating tube-shaped aragonite. In order to simulate the Marine environment, the molar ratioes of Mg2+, K+to Ca2+were adjusted. The morphology and growth of tube-shaped aragonite were researched.2. Glass-slices were used as a template to induce formation and assembly of aragonite. Thermodynamic control can be applied to explain the production of the aragonite. The transformation of three-dimensional nucleation to template-based two-dimensional surface nucleation caused the production of aragonite. Different morphologies, such as hemisphere, twinborn hemisphere and flower-shaped particles, were produced by direction of the glass-slices. A plane was always appeared in these as-synthesized samples because of nucleation and growth of these samples adsorbed on the glass-slices. The formation mechanism of the as-formed sample directed by the glass-slices was proposed, for which is helpful to further study formation processes of biomineralization, such as abalone shell.3. In order to explore the nucleation and growth of carbonate calcium crystals of biological in Marine, the insoluble organic matrix collodion membrane provided nucleation sites for calcium carbonate crystals. Hemisphere carbonate calcium crystals, which were spherical particles at the beginning, were prepared with the help of Mg2+. The effects of solution temperature, aging time and Mg2+concentration on the crystal forms and morphology were investigated in detail.4. Further, to imitate the seawater environment, we added Mg2+and K+in the system. The insoluble organic matrix collodion membrane can provide nucleation sites for calcium carbonate crystals. Solid-solid phase transition from calcite to aragonite was achieved on the surface of collodion membrane. After that, the transform of calcite to aragonite was realized because of the influence of Mg2+and temperature. Hemisphere particles with crude plane or wire-like particles were produced. The growth process of crystals at different temperature has been carried on the preliminary research.