TiO2 mesocrystals built of nanocrystals with exposed {001} facets: facile synthesis and superior photocatalytic ability

A totally novel, extremely easy, much greener and low-cost method has been developed to synthesize TiO2 mesocrystals. These materials are built of TiO2 nanocrystals with similar crystallographic orientation and largely exposed {001} facets. Their unique structure optimizes the relationship between specific surface area, crystallite size and active facets, and therefore leads to superior photocatalytic activity.

Local Microstructure Control of Pure Aluminum Utilizing Fiber-Laser Aided Spot Heating System

Spot heating system utilizing a fiber-laser has been developed in order to control recrystallization, grain growth process and texture development. The newly developed system enables the laser beam to be focused onto the surface of specimen with a minimum diameter of around 10 m. The maximum power of laser in the present system is 100W. Specimens of cold rolled pure aluminum plates of 1mm thick are used for local recrystallization treatment by the spot heating. After laser-spot heating, preferentially recrystallized grains appeared in the irradiated and heat affected region with a diameter depending on the laser power density. The present system enables spot heating on any critical points of the specimen surface. Some laser-heated specimen show locally recrystallized regions occupied by almost single grain having similar crystallographic orientation as that of cold rolled matrix. But the orientation of recrystallized grain is not always the same as that of the matrix. Selective spot heating on grains having peculiar orientation would bring about a possibility of texture control that has not been achieved by means of conventional materials processing.

Structure and Crystallographic Texture of Arthropod Bio-Composites

In this study we present experimental investigations on the microscopic structure, constituent phases, and crystallographic textures of the exoskeleton of three types of decapod crustaceans, namely, lobster, crab, and horseshoe crab. The carapace of such animals is a biological multiphase nano-composite consisting of an organic matrix (crystalline chitin and non-crystalline proteins) and biominerals (calcite, phosphate). The synchrotron measurements of the crystalline chitin and of the biominerals which are embedded in the chitin-protein matrix (in case of lobster and crab) reveal strong textures. The horseshoe crab does not seem to contain notable amounts of crystalline minerals. The Debye-Scherrer images of the lobster specimen suggest that the biominerals form clusters of crystals with similar crystallographic orientation. TEM images support this suggestion. The crystallographic texture of the chitin is arranged with its longest cell axis parallel to the normal of the surface of the exoskeleton.