Magnetic Resonance Studies of Inorganic Oxides and a New Pulse Programming System for Pulsed EMR
Schwartz, Dwight Allen
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Permalink
https://hdl.handle.net/2142/84370
Description
Title
Magnetic Resonance Studies of Inorganic Oxides and a New Pulse Programming System for Pulsed EMR
Author(s)
Schwartz, Dwight Allen
Issue Date
1997
Doctoral Committee Chair(s)
Belford, R. Linn
Department of Study
Chemical Physics
Discipline
Chemical Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
We have investigated several inorganic oxide systems using nuclear and electron magnetic resonance spectroscopies and also report a new pulse programming system for a pulsed S-band EMR spectrometer. We show in a study of simple perovskites (Ca,Sr,Ba)(Ti,Zr) O$\sb3$ that magic-angle spinning O-17 NMR provides unique, highly-resolved spectra in these materials and gives evidence of being useful as a diagnostic tool in mixed phase materials (A$\sb{x}A\sbsp{1-x}{\prime})$BO$\sb3.$ Various used NMR and EMR techniques to study of the commercial borosilicate glasses CGW-3320, CGW-7502, CGW-7740 (Pyrex) and GSC-4, and T-08 (pure silica glass) which had received 5-10 gigarad doses of Co-60 gamma-radiation in the presence and absence of hydrogen gas. We show that B-11, Al-27 and Si-29 MAS NMR spectra contain indications of structural changes in these glasses as a result of large doses of radiation. We also observed the reduction of trace Ti(IV) to Ti(III) when H$\sb2$ gas was present during irradiation of glass samples. Static NMR and EMR studies in the (Na,Li)PO$\sb3$ system indicate a possible mixed alkali effect in the spin-lattice relaxation of Na-23 in NaPO$\sb3$ and Li$\rm\sb{0.4}Na\sb{0.6}PO\sb3.$ Static Na-23 NMR studies of NaPO$\sb3$ reveal the presence of different structural or dynamical environments as a function of temperatures between 23-566 C. We have investigated glass and glass fibers of Li$\rm\sb{0.6}Na\sb{0.4}PO\sb3$ and Na(P$\rm\sb{0.99},V\sb{0.01})O\sb3,$ and show P-31 NMR and EMR evidence that these materials remained structurally isotropic when pulled into fibers. We show that vanadium (in Na(P$\rm\sb{0.99},V\sb{0.01})O\sb3)$ appears to suppress radiolytic unpaired electron and hole defect production which does take place in nominally vanadium-free NaPO$\sb3$ during small doses of gamma-radiation. We describe hardware and software developed for a pulse programming system for a pulsed S-band EMR spectrometer. This system supports user-programmable automatic independent control of all pulse sequence parameters (pulse and delay durations, and pulse phases). We demonstrate the capabilities of this new system in 2-, 3-, and 4-pulse EMR experiments, and also demonstrate a new software suite for interactive simulation and simulation optimization of electron spin echo envelope modulation (ESEEM) patterns using a genetic algorithm.
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