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Careful TEM examination has confirmed the formation of equiaxed α in nanocrystalline β during ageing of a severely deformed metastable β Ti alloy. It is revealed that the Burgers orientation relationship is obeyed upon α nucleation, but grain growth has led to the eventual incoherent α/β interfaces. In addition, intragranular acicular α would form when the β grains prior to ageing are much coarser than ~ 10 nm. [ABSTRACT FROM AUTHOR]

Some peculiarities of straight and zig-zag grain boundaries in multi-crystalline Si ingots were analyzed by Scanning Electron Microscopy-Electron BackScatter Diffraction (SEM-EBSD) and Three Dimensional (3D) grain boundary reconstruction. In the cases where straight grain boundaries were perpendicular to facing {111} planes in the two neighboring grains, they were found parallel, within the measurement accuracy, to the bisector of the two facing {111} planes. This is in agreement with the theory predicting the existence of Facetted-Facetted grooves during the growth of multicrystalline Si. Another grain boundary was corresponding to the predicted Facetted-Rough groove. It was found that the zig-zag grain boundaries were successively composed of {111} twin planes and (...11)/(011) planes, so that the two grains are always in Σ3 relationship. The phenomenon leading to the formation mechanism for these boundaries remains a subject for research. [ABSTRACT FROM AUTHOR]

An elevated-temperature polyol-based colloidal-chemistry approach allows for the development of size-tunable (50 and 86 nm) assemblies of maghemite iso-oriented nanocrystals, with enhanced magnetization. ¹H-nuclear magnetic resonance (NMR) relaxometric experiments show that the ferrimagnetic cluster-like colloidal entities exhibit a remarkable enhancement (4-5 times) in transverse relaxivity when compared to that of the superparamagnetic contrast agent Endorem®, over an extended frequency range (1-60 MHz). The marked increase in the transverse relaxivity r2 at a clinical magnetic field strength (~1.41 T), which is 405.1 and 508.3 mM-1 s-1 for small and large assemblies, respectively, makes it possible to relate the observed response to the raised intra-aggregate magnetic material volume fraction. Furthermore, cell tests with a murine fibroblast culture medium confirmed cell viability in the presence of the clusters. We discuss the NMR dispersion profiles on the basis of relaxivity models to highlight the magneto-structural characteristics of the materials for improved T2-weighted magnetic resonance images. [ABSTRACT FROM AUTHOR]

Abstract: Colloidal SnO2 nanocrystals are prepared via a solvothermal method using oleic acid as a stabilizing agent. Preferred orientation growth along [001] direction of colloidal SnO2 nanocrystals is observed, thereby pure SnO2 nanoparticles with quasi-sphere shape being converted to nanorods due to Gd3+ ions doping. In addition, with increasing Gd3+ doping concentration, the size of SnO2 nanorods decreases. The decrease in size and the change in the shape are ascribed to the increase in the growth rate along [001] direction due to the cationic doping with a surface charge modification. Our results demonstrate a simple method to tune the size and shape of SnO2 nanocrystals through cationic doping with Gd3+ ions. [Copyright &y& Elsevier]

Electrophoretic deposition has emerged as a versatileand preciselytunable approach for the rapid deposition of conformal thin filmsof colloidal nanocrystals. The electrophoretic deposition of phosphorparticles has assumed special significance in recent years as a commerciallyviable means toward the fabrication of large-area, ultrathin high-resolutionemissive display screens. Here, we demonstrate that the anisotropicshape of colloidal ligand-passivated GdOCl nanoplatelets enables theirassembly with remarkable substrate alignment and a high packing densityupon electrophoretic deposition. GdOCl nanocrystals are promisingcandidates for phosphor applications given their low maximum phononcutoff energy, robust chemical stability over prolonged periods ofoperation, and ability to promote efficacious phonon energy transferto dopant ions. Potentiostatic deposition of GdOCl nanoplatelets fromcyclohexane dispersions allows the deposition of individual nanoplateletswith their basal planes parallel to the electrode surface. Tuningthe applied voltage and solution concentration allows control of filmthickness, ranging up to several tens of micrometers. The high degreeof particle alignment is attributed to anisotropic charge distributionand entrainment within electroosmotic flows established in the vicinityof the electrode surface. The oriented high-particle-density GdOClnanoplatelet thin films are possible candidates for phosphor applications,which is illustrated by the green emission from a Tb-doped GdOCl thinfilm on indium tin oxide (ITO)-coated glass. [ABSTRACT FROM AUTHOR]

Abstract: Growth of titanium disilicide (TiSi2) particles on a Ti-deposited Si(113) surface was observed with a scanning tunneling microscope. The direction of the particle growth was specifically related to the anisotropy of the high-index surface. The particles were identified as C54 nano-crystals, and their orientation was determined from the morphology of the silicide facets. The Si(113)-specific growth orientation is explained in terms of the lattice mismatch between C54 TiSi2 and the reconstructed surface structure. [Copyright &y& Elsevier]