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Search Publications by: Igor Levin (Fed)

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Displaying 151 - 175 of 264

Subsolidus Phase Equilibria and Properties in the Magnetic Dielectric System Bi 2 O 3 :Mn 2 O 3+x :Nb 2 O 5

July 20, 2006
Author(s)
Terrell A. Vanderah, M W. Lufaso, A U. Adler, Igor Levin, Juan C. Nino, Virgil Provenzano, Peter K. Schenck, Robert S. Roth
Subsolidus phase relations have been determined for the Bi-Mn-Nb-O system in air (750-900 C). Phases containing Mn2+, Mn3+, and Mn4+ were all observed. Ternary compound formation was limited to pyrochlore, which formed a substantial solid solution region

Phase Formation, Crystal Chemistry, and Properties in the Magnetic Dielectric System Bi 2 O 3- Fe 2 O 3- Nb 2 O 5

June 22, 2006
Author(s)
M W. Lufaso, Terrell A. Vanderah, I M. Pazos, Igor Levin, Juan C. Nino, Virgil Provenzano, Peter K. Schenck, Robert S. Roth
Subsolidus phase relations have been determined for the Bi2O3-Fe2O3-Nb2O5 system in air (900-1075 C). Three new ternary phases were observed Bi3Fe0.5Nb1.5O9 with an Aurivillius-type structure, and two phases with approximate stoichiometries Bi17Fe2Nb31O106

Local Structures and Raman Spectra in the Ca(Zr,Ti)O 3 Perovskite Solid Solutions

February 7, 2006
Author(s)
Igor Levin, Eric J. Cockayne, M W. Lufaso, Joseph C. Woicik, James E. Maslar
Local structures and cation distributions in perovskite Ca(Zr, Ti)O3 solid solutions were analyzed using X-ray absorption fine structure and pair-distribution functions obtained from total neutron scattering. The analyses revealed that the Zr-O and Ti-O

Design of Self-Assembled Multiferroic Nanostructures in Epitaxial Films

January 23, 2006
Author(s)
Igor Levin, Jiying Li, Julia Slutsker, Alexander L. Roytburd
An approach for a rational design of self-assembled multiferroic nanostructures with controlled phase morphologies was demonstrated using the 3-D epitaxial CoFe2O4-PbTiO3 films grown on single-crystal SrTiO3 substrates. The transverse nanostructures

Catalyst-Free Growth of GaN Nanowires

January 1, 2006
Author(s)
Kristine A. Bertness, Norman Sanford, Joy Barker, John B. Schlager, Alexana Roshko, Albert Davydov, Igor Levin
We have grown GaN and AlGaN nanowires on Si (111) substrates with gassource molecular beam epitaxy (MBE). No metal catalysts were used. The nanowires displayed a number of interesting materials properties, including room-temperature luminescence intensity

High Degree of Crystalline Perfection in Spontaneously Grown GaN Nanowires

January 1, 2006
Author(s)
Kristine A. Bertness, Alexana Roshko, Albert Davydov, Igor Levin, Mark D. Vaudin, Joy Barker, John B. Schlager, Norman Sanford, Larry Robins
We have grown a variety of isolated GaN nanowires using gas-source molecular beam epitaxy (MBE) and characterized their structural and optical properties. The nanowires have demonstrated a number of promising materials characteristics, including low defect

Effect of Nitrogen on Band Alignment in HfSiON Gate Dielectrics

November 22, 2005
Author(s)
Safak Sayan, Nhan V. Nguyen, James R. Ehrstein, James J. Chambers, Mark R. Visokay, Manuel Quevedo-Lopez, Luigi Colombo, T Yoder, Igor Levin, Daniel Fischer, M Paunescu, Ozgur Celik, Eric Garfunkel
We have studied the band alignment of HfSiO and HfSiON films by soft x-ray photoemission (SXPS), oxygen K-edge x-ray absorption (XAS), and spectroscopic ellipsometry. Nitridation of HfSiO reduced the band gap by 1.50+- 0.05eV and the valence and conduction

Optical Bandgaps and Composition Dependence of Hafnium Aluminate Thin Films grown by Atomic Layer Chemical Vapor Deposition

November 17, 2005
Author(s)
Nhan V. Nguyen, Safak Sayan, Igor Levin, James R. Ehrstein, I.J.R. Baumvol, C. Driemeier, L Wielunski, Pui-Yee Hung, Alain C. Diebold
Hafnium-aluminate (HfAlO) films grown on Si by Atomic Layer Chemical Vapor Deposition (ALCVD) of different aluminum contents were investigated in this article. Vacuum Ultra-Violet Spectroscopic Ellipsometry (VUV-SE), high Resolution Transmission Electron

The Relation between Crystalline Phase, Electronic Structure and Dielectric Properties in High-K Gate Stacks

September 28, 2005
Author(s)
Safak Sayan, Mark Croft, Nhan Van Nguyen, Tom Emge, James R. Ehrstein, Igor Levin, John S. Suehle, Robert A. Bartynski, Eric Garfunkel
As high permittivity dielectrics approach use in metal-oxide-semiconductor field effect transistor (MOSFET) production, an atomic level understanding of their electronic, and dielectric properties are being rigorously examined. The valence and conduction

Growth habits and defects in ZnO nanowires grown on GaN/sapphire substrates

August 31, 2005
Author(s)
Igor Levin, Albert Davydov, Babak Nikoobakht, Norman Sanford, Pavel Mogilevsky
Growth habits and defects in epitaxial ZnO nanowires grown from Au catalyst on (00.1) GaN/sapphire substrate using the vapor-liquid-solid (VLS) technique were studied using electron microscopy and x-ray diffraction. The results revealed presence of both

Growth Habits and Defects in ZnO Nanowires Grown on GaN/Sapphire Substrates

August 31, 2005
Author(s)
Igor Levin, Albert Davydov, Babak Nikoobakht, Norman A. Sanford, Pavel Mogilevsky
Growth habits and defects in epitaxial ZnO nanowires grown from Au catalyst on (0001) GaN/sapphire substrate using Vapor-Liquid-Solid (VLS) technique were studied using electron microscopy and X-ray diffraction. The results revealed presence of both