Orientational Dissolution Of Calcite In Inorganic Solutions

The investigation of calcium carbonate can not only reveal the relationshipbetween the crystallographic structure and property of biological materials, but alsodirect the fabrication of biological materials with template. This dissertation focuseson investigating crystallographic structure of calcite and fabrication microstructurewith biomacromolecules.We have successfully got the three-dimensional micropyramids arrays of [001]orientation with four to six arrises on calcite sheets in different inorganic solutionsand demonstrated the dissolution progress in different time and concentration.Ammonium solution lead to the distinct orientational dissolution of calcite, result tothe model micropyramids with four or six arrises. We analyzed these arrises ofmicropyramids through SEM and software, and determined these correspondingcrystal orientations in (104) plane. Cations and anions each played an important rolein affecting the morphological structure of micropyramids. The crystal orientationscorresponding to micropyramids were determined by interaction of inorganic ions toCa2+, CO32-ions on calcite planes, which means the capacity of calcite tomicropyramids arrays with various geometric construction could be used in drugdelivery and provides potential for fabricate new structural materials.Sea urchin spicule and shell were composed of Mg-calcite with the samecrystallographic structure as calcite. When got dissolution in ammonium solution(NH4Cl, NH4Ac), nanorods with [001] orientation and nanosteps with {104} planeswere got, which owed the similar structure of calcite dissolution, and it illustrated thatMg-calcite in Sea urchin possessed resemblance in dissolution to calcite.