The emergence of third-generation photovoltaics based on Si relies on tunable bandgap materials with embedded nanocrystalline Si. One of the most promising approaches is based on the mixed-phase Si1 - xCx. We have investigated the light absorption controllability of nanocrystalline Si-embedded Si1 - xCx produced by thermal annealing of the Si-rich Si1 - xCx and composition-modulated superlattic...

Experimental methods are demonstrated for studying pressure-dependent material properties and solid phases unattainable at ambient pressure with high-pressure synchrotron nuclear resonance techniques. Pressure presents an intriguing experimental parameter for investigating the problem of excess low-energy (<12 meV) vibrational modes in nanocrystalline materials. A satisfactory explanation for t...

R. Meyer, 2, ∗ Laurent J. Lewis, S. Prakash, and P. Entel Département de physique et Groupe de Recherche en Physique et Technologie des Couches Mince (GCM), Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal (Québec), Canada H3C 3J7 Institut für Physik, Universität Duisburg-Essen, Lotharstraße 1, D-47048 Duisburg, Germany Département de physique et Groupe de Recherche en Physiq...

Engineering materials with nanocrystalline structure could be exploited under simultaneous action of mechanical loading and corrosion environments; therefore, their corrosion resistance is important. Surface nanocrystalline structure was generated on middle carbon steels by severe plastic deformation using the method of mechanical pulse friction treatment. This treatment additionally includes h...

Due to their limited length of structural coherence nanocrystalline materials show very diffuse powder X-ray diffraction patterns that are difficult to interpret unambiguously. We demonstrate that a combination of high-energy X-ray powder diffraction and atomic pair distribution function analysis can be used to both assess the geometry (i.e., size and shape) and determine the internal atomic or...

An inverse Hall–Petch effect has been observed for nanocrystalline materials by a large number of researchers. This effect implies that nanocrystalline materials get softer as grain size is reduced below a critical value. Postulated explanations for this behavior include dislocation-based models, diffusion-based models, grain-boundary-shearing models and two-phase-based models. In this paper, w...

This paper discusses three aspects that have not been looked into within mechanistic model for rationalizing observed behavior of nanocrystalline materials. (1) For the nano-materials with low energy barrier to emit the trailing partial after the leading partial, such as nanocrystalline Al (nc-Al), both partials extend intra-granularly in strengthening effect. (2) In the transition grain-size r...

Over the past decade, efforts have been made to develop nondestructive techniques for three-dimensional (3D) grain-orientation mapping in crystalline materials. 3D x-ray diffraction microscopy and differential-aperture x-ray microscopy can now be used to generate 3D orientation maps with a spatial resolution of 200 nanometers (nm). We describe here a nondestructive technique that enables 3D ori...

3D molecular dynamics simulations are performed to investigate the role of microstructural confinement on room temperature stress-driven grain boundary (GB) motion for a general population of GBs in nanocrystalline Al thin films. Detailed analysis and comparison with experimental results reveal how coupled GB migration and GB sliding are manifested in realistic nanoscale networks of GBs. The pr...

Annealing of amorphous precursor alloys, with compositions (Fe,Co!88M7B4Cu1 ~M5Zr, Nb, Hf!, above their primary crystallization temperature results in the nanocrystallization of the ferromagnetic a8-FeCo phase. This work describes results of the characterization of these alloys, including morphological and chemical stability of the a8-FeCo phase, examination of alloy compositions, and developme...