Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisor: Robert L. Opila, Dept. of Materials Science & Engineering. Includes bibliographical references.

Made available in DSpace on 2014-10-09T12:36:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:25Z (GMT). No. of bitstreams: 1 04451.pdf: 1033007 bytes, checksum: 54e030bafa03853c9dedda585e3f53db (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:36:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:25Z (GMT). No. of bitstreams: 1 04451.pdf: 1033007 bytes, checksum: 54e030bafa03853c9dedda585e3f53db (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

</p> A study of the quadrupole interactions of Ta181 in a polycrystalline hafnium dioxide environment is described in this work. A general introduction to the concepts of angular correlations in nuclear physics is given in Chapter 1 followed by the main outlines of the theory of quadrupole interactions. Instrumental effects involved in the measurement of such an interaction and the analysis of data using Fourier transform methods are discussed. Descriptions of the structure of HfO2 , the factors involved in attaining short time resolutions in timing and the experimental system and methods used in the study are given. The final two chapters contain the results and conclusions with comparison with results from other works.</p> / Thesis / Master of Science (MSc)

No description available.

A dissertation submitted in fulfilment of the requirements of the degree of Master of Science. Department of Chemistry. University of the Witwatersrand. Johannesburg 2016. / The lattice parameters and thermal expansion coefficients for La2Hf2O7, Eu2Hf2O7, Gd2Hf2O7, Y2Hf2O7, Gd2Zr2O7, Y2Zr2O7, Eu2Ti2O7, Gd2Ti2O7, and Y2Ti2O7 were determined relative to temperature over the range of 30°C to 850°C. All materials were determined to be of the pyrochlore phase expect for Y2Hf2O7, which crystallised in the defect fluorite phase. All materials were shown to have positive thermal expansion, which was not consistent over the experimental temperature range. The change in the thermal expansion coefficient was positive for La2Hf2O7, Y2Zr2O7, Eu2Ti2O7 and Y2Ti2O7, of which the largest change was experienced by Y2Zr2O7. The remaining materials experienced a negative change in their thermal expansion coefficients. The largest negative change was experienced by Gd2Ti2O7. It was shown that the x parameter of the 48f oxygen atom increased with increasing temperature. This had the effect of distorting the transition metal octahedral, and creating a more perfect rare-earth cube as the parameter increased. / TG2016

Nanocrystals embedded zirconium-doped hafnium oxide (ZrHfO) high-k gate dielectric films have been studied for the applications of the future metal oxide semiconductor field effect transistor (MOSFET) and nonvolatile memory. ZrHfO has excellent gate dielectric properties and can be prepared into MOS structure with a low equivalent oxide thickness (EOT). Ruthenium (Ru) modification effects on the ZrHfO high-k MOS capacitor have been investigated. The bulk and interfacial properties changed with the inclusion of Ru nanoparticles. The permittivity of the ZrHfO film was increased while the energy depth of traps involved in the current transport was lowered. However, the barrier height of titanium nitride (TiN)/ZrHfO was not affected by the Ru nanoparticles. These results can be important to the novel metal gate/high-k/Si MOS structure. The Ru-modified ZrHfO gate dielectric film showed a large breakdown voltage and a long lifetime. The conventional polycrystalline Si (poly-Si) charge trapping layer can be replaced by the novel floating gate structure composed of discrete nanodots embedded in the high-k film. By replacing the SiO2 layer with the ZrHfO film, promising memory functions, e.g., low programming voltage and long charge retention time, can be expected. In this study, the ZrHfO high-k MOS capacitors that separately contain nanocrystalline ruthenium oxide (nc-RuO), indium tin oxide (nc-ITO), and zinc oxide (nc-ZnO) have been successfully fabricated by the sputtering deposition method followed with the rapid thermal annealing process. Material and electrical properties of these kinds of memory devices have been investigated using analysis tools such as XPS, XRD, and HRTEM; electrical characterizations such as C-V, J-V, CVS, and frequency-dependent measurements. All capacitors showed an obvious memory window contributed by the charge trapping effect. The formation of the interface at the nc-RuO/ZrHfO and nc-ITO/ZrHfO contact regions was confirmed by the XPS spectra. Charges were deeply trapped to the bulk nanocrystal sites. However, a portion of holes were loosely trapped at the nanocrystal/ZrHfO interface. Charges trapped to the different sites lead to different detrapping characteristics. For further improving the memory functions, the dual-layer nc-ITO and -ZnO embedded ZrHfO gate dielectric stacks have been fabricated. The dual-layer embedded structure contains two vertically-separated nanocrystal layers with a higher density than the single-layer embedded structure. The critical memory functions, e.g., memory window, programming efficiency, and charge retention can be improved by using the dual-layer nanocrystals embedded floating gate structure. This kind of gate dielectric stack is vital for the next-generation nonvolatile memory applications.

A series of bi- and tri-dentate amido phosphine ligands H[Ph-PNP] (bis(2-diphenylphosphinophenyl)amine), H[iPr-PNP] (bis(2-diisopropylphosphino- phenyl)amine), H[Cy-PNP] (bis(2-dicyclohexylphosphinophenyl)amine), H[iPr-NP] (N-(2-diphenylphosphinophenyl)-2,6-diisopropylaniline), and H[Me-NP] (N-(2-diphenylphosphinophenyl)-2,6-dimethylaniline) have been synthesized in high yield. Lithiation of these compounds with n-BuLi in ethereal solutions afforded the corresponding lithium complexes. The metathetical reactions of MCl4(THF)2 (M = Zr, Hf) with [iPr-NP]Li(THF)2 or [Me-NP]Li(THF)2 in toluene produced the corresponding [iPr-NP]MCl3(THF) and [Me-NP]2MCl2, respectively, in high yield. In contrast, attempts to prepare [Me-NP]MCl3(THF) and [iPr-NP]2MCl2 led to the concomitant formation of mono- and bis-ligated complexes, from which purification proved rather ineffective. The solution and solid-state structures of [iPr-NP]MCl3(THF) and [Me-NP]2MCl2 were studied by multinuclear NMR spectroscopy and X-ray crystallography. Treatment of PdCl2(PhCN)2 with [iPr-NP]Li(THF)2 in THF afforded dimeric {[iPr- NP]PdCl}2, which was reacted with tricyclohexylphosphine to produce [iPr-NP]PdCl(PCy3). The two phosphorus donors in [iPr-NP]PdCl(PCy3) are mutually cis as indicated by the solution NMR and X-ray crystallographic studies. Both {[iPr-NP]PdCl}2 and [iPr-NP]PdCl(PCy3) are highly active catalyst precursors for Suzuki coupling reactions of a wide array of aryl halides, including those featuring electronically deactivated and sterically hindered characteristics. The metathetical reaction of NiCl2(DME) (DME = dimethoxyethane) with [iPr-PNP]Li(THF) and [Cy-PNP]Li(THF), respectively, produced the diamagnetic nickel complexes [iPr-PNP]NiCl and [Cy-PNP]NiCl. These nickel chloride complexes were reacted with Grignard reagents to afford thermally stable nickel alkyl and aryl complexes [iPr-PNP]NiR and [Cy-PNP]NiR (R = Me, Et, n-Bu, Ph). A series of divalent nickel alkoxo, amido, thiolate complexes [iPr-PNP]NiX and [Cy-PNP]NiX (X = OPh, NHPh, SPh) were also easily prepared. Reaction of H[Ph-PNP] with Ni(COD)2 (COD = cycloocta-1,5-diene) produced the transient [Ph-PNP]NiH, which underwent COD insertion to give [Ph-PNP]Ni(£b1- cyclooctenyl). Instead, reactions of Ni(COD)2 with H[iPr-PNP] and H[Cy-PNP], respectively, afforded isolable diamagnetic complexes [iPr-PNP]NiH and [Cy-PNP]NiH without alkene insertion. The reactivity of these nickel hydride complexes was investigated.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 152-158).

Not available / text