We have studied the effects of straining prior to annealing for lamellar structure formation in a Ti-39at%Al single crystal intending to accelerate the lamellar structure formation and decrease the resultant lamellar spacing via preferential nucleation of γ-TiAl phase at dislocations in α2-Ti3Al phase. In a crystal cold-rolled to 10% reduction before annealing, a fine lamellar structure with 88 nm average spacing was formed by annealing at 1073 K for 1×104 s whereas no lamella were observed in the crystal subjected to the same annealing without cold-rolling. In addition, it was also demonstrated that when the crystal is locally strained by indentation and annealed at 1073 K for 1×104 s, a lamellar structure with 43 nm average lamellar spacing is formed in areas near the indentation and there were no lamella beyond these areas. This means that distributions of lamellae can be controlled by controlling the distribution of strain before annealing.

Metallic nanoparticles may form hierarchical dendrites in the presence of ionic surfactant through self-assembly upon solvent drying at room temperature. With nanoparticle density varying in the drying area on the supporting solid substrate, the morphology and relevant size of the dendrites evolve in different structures. At the region where the nanoparticle density is high, the large dendrite can develop with manifest crystal symmetry. At the low density region, many small sizes of compact crystals can be found, indicating that particle nucleation dominates over the long-range crystal growth. SEM image reveals the ordered stacking of gold nanoplates over the long dendrite branches, resembling the liquid crystal array. We present the possible physical origins to explain the various structures of the assembled dendrites during the solvent evaporation at the interface of solid and air.

Nanosphere lithography (NSL) has been successfully used to nanopattern silicon and glass substrate surfaces using a spin process in conjunction with the chemical functionalized polystyrene nanospheres. Here, we report for the first time the formation of periodic arrays of nanohole and nanopillar on GaAs and GaSb substrates using a combination of NSL, electron beam (E-Beam) evaporation and Bromine Ion Beam Assisted Etching (Br-IBAE). When 250 nm diameter nanospheres were used as a template or mask, periodic arrays of approximate 55 nm hexagonal nanoholes and 39 nm hexagonal nanopillars were obtained from double-layer nanosphere templates, while arrays of approximate 65nm triangular nanohole and 53nm triangular nanopillar were obtained from single-layer nanosphere templates. The high uniformity of these nanohole and nanopillar arrays demonstrates the technique¡¦s potential for applications in the fabrication of novel high performance opto- and electronic devices in the important GaAs and GaSb III-V direct bandgap semiconductors.

Self-organized swelling of a metal-polymer bilayer directed by a corrugated mold was reported. The corrugated pattern by the elastomeric mold was observed from the earlier stages of swelling. The temporal evolution of the self-organized pattern was analyzed theoretically, and the experimental data were well matched with the analysis. The maximum harmonic number for the corrugated wave number was also analyzed. With a relatively large line width, irregular self-organized patterns were observed.