Morphological control of CaCO3 films with large area: effect of additives and self-organization under atmospheric conditions.

Hierarchically structured CaCO(3) films were synthesized at atmospheric conditions (room temperature and 1 atm) without the use of templates or amphiphilic molecules in this process. The resulting CaCO(3) film was formed by self-organization between Ca(OH)(2) and aqueous CO(2). The building blocks of the CaCO(3) film were thought to be CaCO(3) primary nanoparticles that aligned to build higher level structures with greater size, called mesocrystals, depending on the additives. The soluble additives played a key role in the control of the morphology, crystallinity, and polymorphism of the CaCO(3) film, and the effects strongly depended on the type of additive and their concentrations. The additives used in this study decreased the crystallinity of CaCO(3) (calcite) film in the order of glucose > aspartic acid > serine in a manner inversely proportional to the concentration of the additives. In addition, Mg(2+), K(+), and Na(+) ion additives led to the formation of an aragonite phase, the proportion of which increased with the concentration of ions. The threshold concentrations of these ions for the formation of the aragonite phase in CaCO(3) film were found to be in the order of Na(+) > K(+) > Mg(2+).

New approach for fabrication of folded-structure SiO2 using oyster shell.

Inspired by the phenomenological differences of layers in oyster shell and the morphological mimicry of SiO(2) thin film, a folded-structure SiO(2) was created by simple spray deposition system. The folded-structure SiO(2) was analyzed by scanning electron microscopy, energy dispersive spectrometer and microindentation. At the molecular level, the chalky and the folia were assembled and determined through biomineralization based on the differences of soluble protein in layers. At the macro-scale, the granular SiO(2) particles deposited at the surface of shell layers or Ca(OH)(2) and grew into thin film, thus leading to mimic the morphology of substrate.

A new approach to the synthesis of functional thin films: hierarchical synthesis of CaCO3 thin films and their transformation into patterned metal thin films.

A patterned metal thin film was synthesized based on a new approach that allows the formation of thin films with complex shape, hierarchical organization, and controlled size under ambient conditions in an aqueous environment. By using a general coating system, a CaCO(3) thin film was transformed into a patterned metal thin film with functional properties, such as adhesion and hydrophobicity. Atomic force microscopy (AFM) and surface-profiling experiments were carried out to measure the adhesion between the probe tip and the substrate and to determine the film thickness. Separation of the patterned ceramic thin film occurred very easily by means of sputtering and chemical treatment with an acidic solution.