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Applications such as fuel cells, nanoimprinting, integrated systems, sensors and biomimetic require an exquisite control of materials on length scales ranging from angstroms to centimeters. Our research actvities focus on fabrication and characterization of micro-, nano-, and hierarchical metallic structures. We use amorphous metals (metallic glasses) to understand and utilize..

Size and confinement effects on:

Mechanical Properties: Plastic deformation in sub-micron amorphous metals changes from localized to homogeneous. However, there are several contradicting reports citing size, irradiation or geometry being the origin of this change in deformation mechanism. The common challenge of previous studies was their reliance on focused ion beam for sample preparation. In contrast, we use thermoplastic molding which enables damage free fabrication of test specimens with diameters ranging from 10 to 150 nm. The molded samples are characterized by compression (in our lab) and tensile testing (in Prof. Gianola's lab at UPenn).

Thermal Properties: The properties such as glass transition (Tg), crystallization and melting are known to be function of sample size and interface (confinement). Increase as well decrease in Tg has been reported for polymers confined at nano-scale. Polymerization is also affected by the size and confinement media. Such studies are sparse in amorphous metals though size-dependent melting behavior of crystalline metals has been widely studied. We envisage that effect of size and confinement on thermal properties of amorphous metals can provide important insight about their interfacial properties and crystallization mechanisms. In this project, we are investigating free nano-rods and confined nano-rods by scanning calorimetry. 

Functionalization through hierarchical surface patterning (funded by NSF CMMI-1266277)

We target to control the functional (wetting, adhesion, corrosion) properties of metals by engineering their surface topography and chemistry. The focus is on developing new patterning methods and combining them with chemical routes to create micro-, nano-, and hierarchical surfaces with a tunable response. We have successfully demonstrated the fabrication of micro- nano- and hierarchical structures on planar and curved surfaces. The surface properties of these structures will be characterized and the knowledge will be used to optimize the surface properties.

Thick nano-porous films assembled by joining nano-wires

We are developing new fabrication techniques for synthesis of highly porous thick films (> 10 microns) for catalytic applications. Ultra long nano-wires are aligned and joined to produce uniform thick films. We are also interested in the mechanical and thermal properties of these films.

porous film