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Nanoscale Structural Engineering of Ferroelectric Polymers. Final Report for July 2001-June 2005

Description: This final report describes the interaction between multilavered films of polymer ferroelectrics, in our case the copolymers of PVDF formed with TrFE. Langmuir Blodgett deposition of these films allows the deposition of thin, uniform, highly crystalline films. Two type of multilayer stacks are made and characterized. The first consists of multilayer stacks of the copolymer films with 2 different TrFE contents-50% and 20%. By varying the period of the multilayer stacks we see evidence of interac… more
Date: December 1, 2005
Creator: Adenwalla, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Reflection of neutrons from an optical grating

Description: Specular and off-specular neutron intensities were measured at grazing incidence from an optical grating. Thee periodicity of the grating was determined from the locations of the intensity peaks in the off-specular data. An analysis of the widths of the off-specular intensity peaks showed that the effect of the coherence length of the neutron beam on the determination of a surface length scale {approximately}30 {mu}m was negligible compared to that of the instrument resolution. Although the str… more
Date: December 1, 1994
Creator: Munter, Alan E.; Adenwalla, S.; Felcher, G. P. & Zhou, X. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Toward the solution of the inverse problem in neutron reflectometry

Description: The authors show that the chemical depth profile of a film of unknown structure can be retrieved unambiguously from neutron reflection data by adding to the system a known magnetic layer. Three independent reflectivities are obtained by taking measurements with the sample magnetized in a magnetic field perpendicular to the surface and subsequently parallel to it, and using in the latter geometry neutrons polarized either in the direction of the field or opposite to it. The procedure consists of… more
Date: August 1, 1995
Creator: De Haan, V. O.; Van Well, A. A.; Sacks, Paul E.; Adenwalla, S. & Felcher, G. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Changes in electron-phonon coupling across a bulk phase transition in copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%).

Description: We present evidence for a change in electron--phonon coupling across a bulk phase transition. Below the lattice stiffening transition at around 160 K, there is a change in the diffracted peak width observed by neutron and X-ray scattering techniques. Also, the electronic band structure of the copolymer is shifting in binding energy below 160 K, decreasing the density of states near the Fermi level. The value of the effective Debye temperature above the transition temperature is approximately 50… more
Date: November 8, 2000
Creator: Borca, C. N.; Adenwalla, S.; Choi, J.; Robertson, L.; You, H.; Fridkin, V. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Neutron diffraction and reflectivity studies of the Cr Neel transition in Fe/Cr(001) superlatices

Description: The effects on the interlayer coupling of the Cr Neel transition is studied in Fe/Cr(001) superlattices. The Neel transition is suppressed for Cr layer thickness < 42 {angstrom}. For > 42{angstrom} of Cr, the Neel temperature TN initially increases rapidly and then asymptotically approaches its bulk value with a three-dimensional transition-temperature shift exponent value of {lambda}=1.4{+-}0.3. Neutron diffraction confirms both the Cr antiferromagnetic order and the existence of the incommens… more
Date: August 1995
Creator: Fullerton, E. E.; Adenwalla, S. & Felcher, G. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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