Structural evolution of vacancy clusters by combination of cluster units in alpha-iron

The effects of [001] uniaxial strain on the stable structures and structural evolution of vacancy clusters in fcc metals, Cu, Ni, Al and Fe, have been studied and compared. Under uniaxial strain, the clusters in all these metals tend to align parallel or perpendicular to the strain axis under tensile or compressive strain. Moreover, both the body cluster and the {001} planar cluster become the dominant types. In addition, the stacking fault tetrahedron cluster becomes another dominant type in Al under compressive strain. The cluster structures in Fe are disordered under strain possibly because the pure fcc Fe is thermodynamically unstable under the current simulation condition.

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The Energetics of Hydrogen-Vacancy Clusters in BCC Iron

MRS Proceedings ◽

10.1557/opl.2011.1315 ◽

2011 ◽

Vol 1363 ◽

Author(s):

Erin Hayward ◽

Chaitanya S. Deo

Keyword(s):

Binding Energies ◽

Hydrogen Atoms ◽

Weakly Bound ◽

Alpha Iron ◽

Crystalline Materials ◽

Vacancy Clusters ◽

Hydrogen Bubbles ◽

Bcc Iron ◽

Hydrogen Vacancy ◽

Energy Configurations

ABSTRACTWe present a general method for investigating the energetics of small impurity-vacancy clusters in crystalline materials. We use a combination of molecular dynamics and Monte Carlo methods to locate low energy configurations of the bubbles, from which the binding energies of various point defects can be determined. This method is applied to case of hydrogen bubbles in alpha-iron. Clusters with ratios of up to 10 hydrogen atoms to a vacancy are studied. We find that hydrogen does help to stabilize voids in alpha-iron, but that hydrogen is quite weakly bound to these voids. Ratios of up to approximately 4 can be supported at low temperatures.

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Microstructure and reactivity of small metal particles: The role of Ce additives

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121995 ◽

1992 ◽

Vol 50 (1) ◽

pp. 318-319

Author(s):

L.D. Schmidt ◽

K. R. Krause ◽

J. M. Schwartz ◽

X. Chu

Keyword(s):

Atmospheric Pressure ◽

Noble Metals ◽

Mixed Oxides ◽

Catalytic Properties ◽

Chemical Shifts ◽

Catalytic Converter ◽

Structural Evolution ◽

Single Particles ◽

Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

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The Structural Evolution of Morality

10.1017/cbo9780511550997 ◽

2007 ◽

Cited By ~ 59

Author(s):

J. McKenzie Alexander

Keyword(s):

Structural Evolution ◽

Evolution Of Morality

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Electrodeposition of Strained-Layer Superlattices

MRS Proceedings ◽

10.1557/proc-451-413 ◽

1996 ◽

Vol 451 ◽

Cited By ~ 8

Author(s):

T. P. Moffat

Keyword(s):

Charge Transfer ◽

Mass Transport ◽

Structural Evolution ◽

Iron Group ◽

Morphological Instability ◽

Group Metal ◽

Iron Group Metal ◽

Transport Control ◽

Strained Layer Superlattices ◽

Interfacial Charge

ABSTRACTA variety of Cu/(Ni, Co) multilayers have been grown on Cu single crystals by pulse plating from an alloy electroplating bath. Copper is deposited under mass transport control while the iron group metal is deposited under interfacial charge transfer control. The structural evolution of these films is influenced by the morphological instability of the mass transport limited copper deposition reaction and the development of growth twins during iron-group metal deposition. Specular films have been obtained for growth on Cu(100) while rough, defective films were typically obtained for growth on Cu(111) and Cu(110).

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Pattern Formation in Thin Polymer Films: A New Morphology

MRS Proceedings ◽

10.1557/proc-629-ff1.2 ◽

2000 ◽

Vol 629 ◽

Author(s):

Jean-Loup Masson ◽

Peter F. Green

Keyword(s):

Growth Rate ◽

Pattern Formation ◽

Early Stage ◽

Structural Evolution ◽

Distinct Form ◽

Thin Polymer Films ◽

Intermediate Morphology ◽

Thin Polymer ◽

Nonwetting Liquid ◽

Cylindrical Holes

ABSTRACTResearchers have shown that thin, nonwetting, liquid homopolymer films dewet substrates, forming patterns that reflect fluctuations in the local film thickness. These patterns have been shown to be either discrete cylindrical holes or bicontinuous “spinodal-like” patterns. In this paper we show the existence of a new morphology. During the early stage of dewetting, discrete highly asymmetric holes appear spontaneously throughout the film. The nucleation rate of these holes is faster than their growth rate. The morphology of the late stage of evolution, after 18 days, is characterized by a bicontinuous pattern, distinct form conventional spinodal dewetting patterns. This morphology has been observed for a range of film thicknesses between 7.5 and 21nm. The structural evolution of this intermediate morphology is discussed.

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