Sintering of powders is a common means of producing bulk materials when melt casting is impossible or does not achieve a desired microstructure, and has long been pursued for nanocrystalline materials in particular. Acceleration of sintering is desirable to lower processing temperatures and times, and thus to limit undesirable microstructure evolution. Here we show that markedly enhanced sinter...

The first solvent-free crystal structure of PCBM, an organic semiconductor widely used in solvent-free nanocrystalline films in plastic solar cells, is reported and its relevance to structure-property relationships discussed. The PCBM structure, obtained from o-dichlorobenzene solvates by solvent abstraction, was solved using powder diffraction, demonstrating this possibility for functionalized...

A simple and convenient one-step method for synthesis of acridines and their derivatives from condensation of aromatic aldehydes, cyclic diketones, and aryl amines using Cu-doped ZnO nanocrystalline powder as a catalyst is reported. The present protocol provides several advantages such as good yields, short reaction time, easy workup, and simplicity in operation.

B. Ahn*, S. R. Nutt 1. Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089-0241, USA *[email protected] Abstract: Al–Mg alloy powder was mechanically milled in liquid N2 (cryomilling) to produce thermally stable powder with nanocrystalline (NC) microstructure for the manufacture of highstrength alloys. A multi-scale microstructure w...

Ball milling has been shown to produce nanostructures in metal powders through severe repetitive deformation. Ball milling at cryogenic temperatures (cryomilling) is more effective in this capacity due to the low temperature by slowing recovery and minimizing diffusion distances between different components. Nanostructured metals are of interest because of their unique physical and mechanical p...

The influence of short-time milling on the atomic structure of amorphous Co(70.3)Fe(4.7)B(25) has been investigated by differential scanning calorimetry (DSC), x-ray powder diffraction (XRD), vibrating sample magnetometer (VSM) and x-ray absorption fine-structure (XAFS) techniques. Our results prove that the milling process crystallizes the initially amorphous sample and that the degree of inhe...

Mesoporous aggregates of nanocrystalline zeolites with MFI and BEA frameworks have been synthesized using a one-pot and single structure directing agent. The effect of different reaction conditions, such as temperature, time, pH and water content, on the particle size, surface area and mesopore volume has been studied. Nanocrystalline and mesoporous ZSM-5, β and Y zeolites were modified with di...

Abstract: Nanocrystalline MgAl2O4 spinel powder was synthesized using metal nitrates and a polymer matrix-based composed of sucrose and polyvinyl alcohol (PVA). The precursor and the calcined powders were characterized by simultaneous thermal analysis (STA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). According to XRD res...

Carbides, borides and nitrides of high melting transition metals were synthesized by high energy ball milling of elemental powder mixtures. The obtained hard material phases show a nanocrystalline structure with a saturation value of the crystal sizes between 7-8 nm. The kinetics of the reaction were investigated, and the nanocrystalline powders were densified by HIP. Introduction The formation...

Al–Mg alloy powder was cryomilled to achieve a nanocrystalline (NC) structure having an average grain size of 50 nm with high thermal stability, and then consolidated by quasi-isostatic forging. The consolidation resulted in a bulk material with ultrafine grains of about 250 nm, and the material exhibited enhanced strength compared to conventionally processed Al–Mg alloy. The hardness of as-cry...