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Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Competitive Abnormal Grain Growth between Allotropic Phases in Nanocrystalline Nickel

ADVANCED MATERIALS, Issue 10 2010
L. N. Brewer
Electron backscatter diffraction-generated phase map showing the distribution of the abnormally grown grains for both the face centered cubic (red) and hexagonal close packed (blue) phases. Annealing condition was 17,h at 548,K. [source]

The calculation of a parent grain orientation from inherited variants for approximate (b.c.c.,h.c.p.) orientation relations

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2002
N. Gey
The orientations of parent , grains are evaluated from several , variants inherited from the same parent during the body-centred cubic (b.c.c.) to hexagonal close packed (h.c.p.) phase transformation. The proposed calculation, based on orientation correlating and orientation averaging, is particularly useful when the inherited variants are not strictly related to the parent orientation by a strict Burgers orientation relation or when the orientations of the inherited volumes vary slightly at different locations of the variant. This method of parent identification from variant orientations is an improvement of a previously published method. [source]

Porous anodic alumina thin films on Si: interface characterization

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2008
V. Gianneta
Abstract Porous anodic alumina (PAA) thin films (thickness , 50nm) were fabricated on Si by anodization of thin Al films under constant voltage of 20 V in sulphuric acid aqueous solution. The films exhibit cylindrical vertical pores of diameter , 13,15 nm, arranged in hexagonal close packed structure. Electrochemical oxidation of the Si substrate through PAA, used as masking layer with openings in the pores, resulted in the formation of SiO2 dots at each pore tip. Two different kinds of films, namely with or without SiO2 dots at pore tips, were fabricated. In order to characterize the electrical quality of the interface of PAA thin films with Si, C-V and G-V measurements were performed on Metal-Insulator-Semiconductor (MIS) structures with Al metallization. The measurements were carried out in the voltage range +1.0 V to ,3.0 V in steps of 0.05 V and in the frequency range 1 MHz to 100 Hz. The typical form of C-V and G-V curves of a MIS structure was obtained. In order to determine the interface trap density Dit, C-f and G-f measurements were performed as a function of the applied gate voltage in the depletion region. Dit was evaluated following the Conductance Method (E. H. Nicollian, and J. R. Brews, MOS Physics and Technology (J. Wiley & Sons, New York, 1982), p. 222 [1]). Both types of samples exhibit values of Dit in the order of 1011 eV,1cm,2. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

On the crystal structure of Cr2N precipitates in high-nitrogen austenitic stainless steel.

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2006

The crystal structure and order,disorder transition of Cr2N were investigated utilizing transmission electron microscopy (TEM). Based on the analyses of selected-area diffraction (SAD) patterns, the crystal structure of the ordered Cr2N superstructure was confirmed to be trigonal (), characterized by three sets of superlattice reflections (001), (0) and (1). During electron irradiation, the superlattice reflections gradually disappeared in the regular sequence (001), (0) and (1), indicating that the order,disorder phase transition of Cr2N occurred. The convergent-beam electron diffraction (CBED) observation revealed that the space group of disordered Cr2N is P63/mmc, which corresponds to an h.c.p. (hexagonal close packed) sublattice of metal atoms with a random distribution of N atoms in six octahedral interstices. The redistribution model of N atoms through the order,disorder transition is discussed based on the characteristics and disappearing sequence of superlattice reflections. [source]