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Search Publications by: Igor Levin (Fed)

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Displaying 101 - 125 of 264

Ferri- to ferro-magnetic transition in the martensitic phase of a Heusler alloy

September 15, 2012
Author(s)
Robert D. Shull, Lawrence H. Bennett, Virgil Provenzano, Y. N. Jin, Igor Levin, E. Della Torre
During the past decade the magnetic properties of Heusler alloys have been extensively studied, motivated in part by the observation of large magnetocaloric effect (MCE) peaks displayed by these alloys near room temperature. We present new data and

Ti_(12.5)Zr_(21)V_(10)Cr_(8.5)Mn_(x)Co_(1.5)Ni_(46.5-x)AB_(2)-type metal hydride alloys for electrochemical storage application: Part 1. Structural characteristics

August 3, 2012
Author(s)
Leonid A. Bendersky, Ke Wang, Igor Levin, Dale E. Newbury, K. Young, B. Chao, Adam A. Creuziger
The microstructures of a series of AB_(2)-based metal hydride alloys (Ti_(12.5)Zr_(21)V_(10)Cr_(8.5)Mn_(x)Co_(1.5)Ni_(46.5-x)) designed to have different fractions of non-Laves secondary phases were studied by x-ray diffraction, scanning electron

Ultimate bending strength of Si nanowires

April 11, 2012
Author(s)
Gheorghe Stan, Sergiy Krylyuk, Albert Davydov, Igor Levin, Robert F. Cook
Test platforms for the ideal strength of materials are provided by almost defect-free nanostructures (nanowires, nanotubes, nanoparticles, for example). In this work, the ultimate bending strengths of Si nanowires with radii in the 20 nm to 60 nm range

Crystal Structure of the Type I Clathrate Ba8Ni4Ge42

March 30, 2012
Author(s)
Winnie K. Wong-Ng, Qingzhen Huang, Igor Levin, Joseph C. Woicik, Xun Shi, Jihui Yang, James A. Kaduk
The crystal structure of Type-I clathrate Ba8Ni4Ge42 has been determined using neutron powder diffraction, transmission electron microscopy (TEM, for possible superlattice), extended X-ray absorption fine structure measurements. Ba8Ni4Ge42 is cubic with

Effect of AlN Buffer Layer Properties on the Morphology and Polarity of GaN Nanowires Grown by Molecular Beam Epitaxy

September 8, 2011
Author(s)
Matthew D. Brubaker, Kristine A. Bertness, Norman A. Sanford, Albert Davydov, Igor Levin, Devin M. Rourke, Victor M. Bright
Low temperature AlN buffer layers grown by plasma-assisted Molecular Beam Epitaxy (MBE) on Si (111) were found to significantly affect the subsequent growth morphology of GaN nanowires. The AlN buffer layers exhibited nanowire-like columnar protrusions

Tapering Control of Si Nanowires Grown from SiCl4 at Reduced Pressure

December 15, 2010
Author(s)
Sergiy Krylyuk, Albert Davydov, Igor Levin
Device applications of tapered Si nanowire (SiNW) arrays require reliable technological approaches for fabricating nanowires with controlled shape and orientation. In this study, we systematically explore effects of growth conditions on tapering of Si

Enhanced Mass Transport in Ultra-Rapidly-Heated Ni/Si Thin-Film Multilayers

November 15, 2009
Author(s)
Lawrence P. Cook, Richard E. Cavicchi, Nabil Bassim, Susie Eustis, Winnie Wong-Ng, Igor Levin, Ursula R. Kattner, Carelyn E. Campbell, Christopher B. Montgomery, William F. Egelhoff Jr., Mark D. Vaudin
We have investigated multilayer and bilayer Ni/Si thin films by nano-differential scanning calorimetry (DSC) at ultra rapid scan rates, in a temperature-time regime not accessible with conventional apparatus. DSC experiments were completed at slower scan

A Combined Fit of Total Scattering and Extended X-ray Absorption Fine Structure Data for Local-Structure Determination in Crystalline Materials

October 5, 2009
Author(s)
Igor Levin, Victor L. Krayzman, Joseph C. Woicik, Terrell A. Vanderah, M. G. Tucker, Thomas Proffen
Reverse Monte Carlo (RMC) refinements of local structure using a simultaneous fit of x-ray/neutron total scattering and EXAFS data were developed to incorporate an explicit treatment of both single- and multiple-scattering contributions to EXAFS. The

Structural Changes behind the Diffuse Dielectric Response in AgNbO3

March 13, 2009
Author(s)
Igor Levin, Victor L. Krayzman, Joseph C. Woicik, J. Karapetrova, T. Proffen, M. G. Tucker, I. M. Reaney
Structural changes among the so-called M-polymorphs of AgNbO3 were analyzed using combined high-resolution X-ray diffraction, neutron total scattering, electron diffraction, and X-ray absorption fine structure measurements. These polymorphs crystallize