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Vacancy related defects in thin film Pb(ZrTi)O{sub 3} materials

Description: Positron annihilation techniques have been applied to characterize vacancy-related defects in ferroelectric thin film structures. Variable energy positron beam measurements were carried out on doped and undoped Pb(ZrTi)O{sub 3} (PZT) samples subjected to different post-deposition cool down and anneal conditions. The PZT was deposited by sol-gel with either with platinum or RuO{sub 2} electrodes, or by laser ablation with La{sub 0.5}Sr{sub 0.5}CoO{sub 3} electrodes. The RuO{sub 2} and La{sub 0.5… more
Date: December 31, 1994
Creator: Krishnan, A.; Keeble, D. J.; Ramesh, R.; Warren, W. L.; Tuttle, B. A.; Pfeffer, R. L. et al.
Partner: UNT Libraries Government Documents Department
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An investigation of catalytic active phase-support interactions by IR, NMR and x-ray absorption spectroscopies. Progress report, January 15, 1992--September 15, 1992

Description: Active catalytic phases (metal, mixed metals, oxide or mixed oxides) interacting with oxide support on which the active phase is dispersed can affect the percentage exposed, the morphology of supported particles, the degree of reducibility of cations, etc., in a variety of ways. Our objective is to characterize the physical chemistry of the active phase-oxide support interaction by spectroscopic methods and to correlate this structure with catalytic function. Two catalytic systems and their ass… more
Date: September 1, 1992
Creator: Haller, G. L.
Partner: UNT Libraries Government Documents Department
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4f heavy fermion photoelectron spectra do not exhibit the Kondo scale

Description: It has been the authors contention for some time that the Single Impurity Anderson Model (SIAM), as extended by Gunnarsson and Schonhammer (GS), or the non-crossing approximation (NCA), does not correctly describe the 4f photoelectron spectra of heavy fermions. Recently, they have concentrated on Yb heavy fermions since in these materials the Kondo resonance (KR) is fully occupied and thus accessible via photoemission. In particular, they have repeatedly pointed out that the width, position, sp… more
Date: February 1, 1994
Creator: Arko, A. J.; Joyce, J. J.; Andrews, A. B.; Blyth, R. I. R.; Bartlett, R. J.; Fisk, Z. et al.
Partner: UNT Libraries Government Documents Department
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Structure and shear response of lipid monolayers. Progress report, July 1, 1989--June 31, 1990

Description: Organic monolayers and multilayers are both scientifically fascinating and technologically promising; they are, however, both complex systems and relatively inaccessible to experimental probes. In this Progress Report, we describe our X-ray diffraction studies, which have given us substantial new information about the structures and phase transitions in monolayers on the surface of water; our use of these monolayers as a unique probe of the dynamics of wetting and spreading; and our studies of … more
Date: February 1, 1990
Creator: Dutta, P. & Ketterson, J. B.
Partner: UNT Libraries Government Documents Department
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[Investigation of the structure and phase relations of C-S-H gels]

Description: (C-S-H stands for calcium silicate hydrate.) The following areas of study are reported: solution-derived C-S-H, hydration of alite at constant pH, and hydrothermal synthesis of tobermorite.
Date: May 1, 1994
Partner: UNT Libraries Government Documents Department
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Inelastic scattering in condensed matter with high intensity Moessbauer radiation. Final technical report, December 1, 1989--November 30, 1992

Description: The QUEGS facility at MURR has produced a number of new results and demonstrated the range of potential applications of high resolution, high intensity Moessbauer scattering. This work has been carried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and other systems, manuscripts submitted on alkali halides (Phys. Rev. B) and accurate Moessbauer lineshape measurements (Phys. Rev. C), and manuscripts in preparation on glycerol, NiA… more
Date: February 1, 1993
Creator: Yelon, W. B. & Schupp, G.
Partner: UNT Libraries Government Documents Department
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NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts. Quarterly technical progress report, December 15, 1991--March 15, 1992

Description: During this period, we focused our attention in analyzing the magnetic nature of the extensively used trimetallic catalyst system Cu-Co-Cr for the production of higher alcohols. We believe that there could be some correspondence between the catalytic and magnetic behaviors of the transition metal catalyst systems. Both the morphology and metallic charge distribution of the particles are known to govern the catalytic as well as the magnetic properties of the system.
Date: May 4, 1992
Creator: Murty, A. N.
Partner: UNT Libraries Government Documents Department
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X-ray and {Gamma}-ray spectroscopy of solids under pressure. Annual technical progress report, November 1993--October 1994

Description: During this period, synchrotron beam time (approx. 2 weeks/year) was obtained from the Stanford Synchrotron Radiation Laboratory. The following areas of study are reported: XAFS studies of polyhedral solids (ReO{sub 3}, perovskites, rubidium tungsten bronze), Moessbauer study of sodium nitroprusside, XAFS studies of phase transition mechanisms (effects of high pressure on metallic Fe), and multiple scattering analysis of XANES.
Date: April 30, 1994
Creator: Ingalls, R. L.
Partner: UNT Libraries Government Documents Department
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[Gamma scattering in condensed matter with high intensity Moessbauer radiation]

Description: This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.
Date: June 1, 1992
Partner: UNT Libraries Government Documents Department
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NMR imaging of components and materials for DOE application

Description: The suitability for using NMR imaging to characterize liquid, polymeric, and solid materials was reviewed. The most attractive applications for NMR imaging appear to be liquid-filled porous samples, partially cured polymers, adhesives, and potting compounds, and composite polymers/high explosives containing components with widely varying thermal properties. Solid-state NMR line-narrowing and signal-enhancing markedly improve the imaging possibilities of true solid and materials. These technique… more
Date: December 1, 1993
Creator: Richardson, B. R.
Partner: UNT Libraries Government Documents Department
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Application of spin-sensitive electron spectroscopies to investigations of electronic and magnetic properties of solid surfaces and epitaxial systems. Progress report, 1 November 1992--31 October 1993

Description: Research during this year focused on angular dependence of polarization of electrons backscattered from metallic surfaces, as a function of energy loss, using spin-polarized electron energy loss spectroscopy (SPEELS), and on dynamics of metastable He(2{sup 3}S) deexcitation at Xe-covered metallic surfaces using spin-polarized metastable deexcitation spectroscopy (SPMDS). In the SPEELS study, the data from Au, Ag, Mo, and Fe surfaces suggest that all inelastically scattered electrons underwent s… more
Date: April 1, 1993
Creator: Walters, G. K. & Dunning, F. B.
Partner: UNT Libraries Government Documents Department
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X-ray scattering studies of non-equilibrium ordering processes. Progress report, November 1, 1990--October 31, 1991

Description: We report on the progress of the project entitled ``X-ray Scattering Studies of Non-Equilibrium Ordering Processes.`` The past year has seen continued progress in the study of kinetic effects in metallic binary alloys and polymers. In addition, work has begun on a low dimensional CDW system: blue bronze. A sample chamber has been constructed to perform small angle neutron scattering measurements on a model quantum system with phase separation: solid He3/He4. Work is continuing on magnetic syste… more
Date: December 31, 1991
Creator: Nagler, S. E.
Partner: UNT Libraries Government Documents Department
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Two dimensional NMR and NMR relaxation studies of coal structure. Progress report, October 1, 1993--December 31, 1993

Description: Four major areas of inquiry are being pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups that determine the reactivity of coals. Special attention is being paid to methods that are compatible with the very high magic angle sample spinning rates needed for operation at the high magnetic field strengths available today. Polarization inversion methods utilizing the difference in heat capacities of small groups of spins… more
Date: December 31, 1993
Creator: Zilm, K. W.
Partner: UNT Libraries Government Documents Department
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FEFF5: An ab initio multiple scattering XAFS code

Description: FEFF5 is an efficient automated code which calculates multiple scattering (MS) curved wave XAFS spectra for molecules and solids. The theoretical ingredients and approximations contained in the code are revised, with the aim of describing the how XAFS spectra are efficiently simulated. The FEFF5 code consists of 4 independent modules: a scattering potential and phase shift module, a path finder module, a scattering amplitude module and an XAFS module. Multiple scattering Debye-Waller factors ar… more
Date: December 31, 1992
Creator: Rehr, J. J. & Zabinsky, S. I.
Partner: UNT Libraries Government Documents Department
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Neutron scatter studies of chromatin structure related to functions. Progress report, July 1, 1988--June 30, 1989

Description: Neutron scatter studies have been performed at LANSCE, LANL and at the Institute Laue Langevin, Grenoble, France. In the previous progress report (April 1, 1988--July 1, 1988) the following objectives were listed: shape of the histone octamer; location of the N-terminal domains of histone in the nucleosome core particle (specific aim 1 of original grant proposal); effect of acetylation on nucleosome structure (specific aim 2); location of the globular domain of histone H1 (specific aim 6); and … more
Date: December 31, 1989
Creator: Bradbury, E. M.
Partner: UNT Libraries Government Documents Department
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Magnetic resonance studies of photo-induced electron transfer reactions. Final report, June 1, 1990--May 31, 1993

Description: Fourier Transform Electron Paramagnetic Resonance (FT EPR) is useful in study of photochemical reactions: a microwave pulse rotates the electron spin magnetization vector from z (magnetic field) into xy plane ({pi}/2 pulse); the time evolution of magnetization in xy plane, the free induction decay (FID), is sampled. Fourier transform of FID gives the frequency domain EPR spectrum of the free radicals, and the method is ideal for time-resolved studies of free radicals produced by pulsed-laser ex… more
Date: November 1, 1992
Creator: van Willigen, H.
Partner: UNT Libraries Government Documents Department
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Positron studies in catalysis research. Progress report, September 1993--April 1994, and final report, 15 January 1990--14 January 1994

Description: During the past eight months, the authors have made progress in several areas relevant to the eventual use of positron techniques in catalysis research. They have come closer to the completion of their positron microscope, and at the same time have performed several studies in their non-microscopic positron spectrometer which should ultimately be applicable to catalysis. The current status of the efforts in each of these areas is summarized in the following sections: Construction of the positro… more
Date: June 1, 1994
Partner: UNT Libraries Government Documents Department
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Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Technical progress report, January 1992--March 1992

Description: Low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals in th… more
Date: May 1, 1992
Creator: Song, C.; Saini, A. K.; Hatcher, P. G. & Schobert, H. H.
Partner: UNT Libraries Government Documents Department
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Three-dimensional nuclear magnetic resonance imaging of green-state ceramics

Description: Objective is the development of nuclear magnetic resonance imaging techniques and technology applicable to the nondestructive characterization of green-state ceramics. To this end, a three-dimensional (3-D) NMR imaging technique has been developed, based on a back-projection acquisition protocol in combination with image reconstruction techniques that are based on 3-D Radon transform inversion. The method incorporates the experimental flexibility to overcome many of the difficulties associated … more
Date: September 1, 1991
Creator: Dieckman, S. L.; Gopalsami, N.; Ford, J. M.; Raptis, A. C.; Ellingson, W. A.; Rizo, P. et al.
Partner: UNT Libraries Government Documents Department
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Inhibition of retrogressive reactions in coal/petroleum co-processing. Quarterly technical progress report, January 1, 1992--March 31, 1992

Description: The overall objective of this project is to develop a fundamental understanding of the reactions occurring at the onset of coke formation during the CO-processing of coals with action of chemical components, or groups of components, in coals and petroleum feedstocks to quantify and rank the effects of these components in retarding or enhancement of coke formation. The work involves bench scale reactions in microautoclaves, supplemented by studies of the carbonaceous residues by such techniques … more
Date: May 1, 1992
Creator: Schobert, H. H. & Tomic, J.
Partner: UNT Libraries Government Documents Department
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