The large fraction of material residing at grain boundaries in nanocrystalline metals and alloys is responsible for their ultrahigh strength, but also undesirable microstructural instability under thermal and mechanical loads. However, the underlying mechanism of stress-driven microstructural evolution is still poorly understood and precludes rational alloy design. Here we combine quantitative ...

A contemporary question in the intensely active field of periodic mesoporous organosilica (PMO) materials is how large a silsesquioxane precursor can be self-assembled under template direction into the pore walls of an ordered mesostructure. An answer to this question is beginning to emerge with the ability to synthesize dendrimer, buckyball, and polyhedral oligomeric silsesquioxane PMOs. In th...

Grain boundary networks should play a dominant role in determining the mechanical properties of nanocrystalline metals. However, these networks are difficult to characterize and their response to deformation is incompletely understood. In this work, we study the grain boundary network of nanocrystalline Ni and explore whether it can be modified by plastic deformation. Mechanical cycling at room...

Plastic deformation of materials occurs by the motion of defects known as dislocations and disclinations. High-resolution transmission electron microscopy was used to directly reveal the individual dislocations that constitute partial disclination dipoles in nanocrystalline, body-centered cubic iron that had undergone severe plastic deformation by mechanical milling. The mechanisms by which the...

Scanning probe microscopy techniques (SPM) have been applied to a rapidly improvement in the characterization of metal oxide nanocrystalline. These materials are widely used in photon-to-electricity conversion devices, such as dye-sensitized solar cells. The surface properties of such nanocrystalline determine the devices’ performance. SPM imaging of nanocrystal surfaces and nanoscale systems h...

Amorphous and nanocrystalline carbon films possess special chemical and physical properties such as high chemical inertness, diamond-like properties, and favorable tribological proprieties. The materials usually consist of graphite and diamond microstructures and thus possess properties that lie between the two. Amorphous and nanocrystalline carbon films can exist in different kinds of matrices...