Submitted by FRANCISCO XAVIER DE CAMPOS null (franciscoxc1@hotmail.com) on 2017-03-01T22:20:44Z No. of bitstreams: 1 Tese_Francisco_Versão Final.pdf: 6434767 bytes, checksum: 1bd6138a771979437fdd6c3bb6d33b68 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-07T17:39:41Z (GMT) No. of bitstreams: 1 campos_fx_dr_araiq.pdf: 6434767 bytes, checksum: 1bd6138a771979437fdd6c3bb6d33b68 (MD5) / Made available in DSpace on 2017-03-07T17:39:41Z (GMT). No. of bitstreams: 1 campos_fx_dr_araiq.pdf: 6434767 bytes, checksum: 1bd6138a771979437fdd6c3bb6d33b68 (MD5) Previous issue date: 2017-02-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Foram sintetizados os compostos Ln(Mef)3, sendo que Ln representa os lantanídeos trivalentes (La ao Lu e o ítrio (Y) e o Mef representa o mefenamato (C15H14NO2-). Os compostos foram sintetizados por adição de solução de mefenamato de sódio sobre solução dos cloretos de lantanídeos e ítrio, sob agitação e aquecimento, e consequentemente foi feita a filtragem, lavagem e secagem dos compostos. A caracterização dos compostos no estado sólido, foi realizada utilizando as técnicas de difratometria de raios X pelo método do pó, complexometria, espectroscopia de absorção na região do infravermelho com transformada de Fourier (FTIR) e pelas técnicas termoanalíticas: termogravimetria e calorimetria exploratória diferencial simultâneas (TG-DSC), e análise dos gases desprendidos (EGA) por espectroscopia de absorção na região do infravermelho com transformada de Fourier (EGA: TG-FTIR). Os resultados forneceram informações sobre o comportamento térmico, estequiometria dos compostos estudados, cristalinidade, sítios de coordenação e também foi possível identificar os principais produtos gasosos desprendidos durante o aquecimento. / The Ln(Mef)3 compounds, where Ln represents the trivalent lanthanides (La to Lu) and yttrium (Y), and Mef represents mefenamate (C15H14NO2 -), were synthesized. The synthesis was perfomed by addition of sodium mefenamate solution to the lathanides and yttrium chloride solutions, with stirring and heating, and the compounds were filtered, washed and dried. The characterization of the compounds in the solid state was carried out using the techniques of X-ray diffraction powder pattern, complexometry, infrared spectroscopy (FTIR) and by thermoanalytical techniques: simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), and evolved gas analysis (EGA) by infrared spectroscopy (EGA: TG-FTIR). The results provided information on the thermal behavior of the studied compounds as stoichiometry, crystallinity and coordination sites. It was also possible to identify the main gaseous products evolved during the heating.

Abstract not available

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 180-182). Also available on the Internet.

Thesis (M.S.)--Rochester Institute of Technology, 1989. / Includes bibliographical references (leaves 62-64).

Thesis (Ph.D.) -- McMaster University, 1999. / Disk in pocket. Includes bibliographical references (leaves 232-237). Also available via World Wide Web.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 180-182). Also available on the Internet.

Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on June 29, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry, University of Alberta." Includes bibliographical references.

Thesis (Ph. D.)--Montana State University--Bozeman, 2003. / Typescript. Chairperson, Graduate Committee: Rufus L. Cone. Includes bibliographical references (p. 361-380).

>Magister Scientiae - MSc / In the past few decades, the studies of f-electron materials have revealed unusual physical properties such as Fermi-liquid, non-Fermi-liquid behaviour at low temperatures, heavy- Fermion behaviour, valence fluctuation, Kondo effect, superconducting and magnetic ordering. These materials include binary and ternary compounds and alloys with Cerium (Ce) or Ytterbium (Yb) based rare earth elements or Uranium (U) based actinide element. In these systems the localized magnetic moments formed by Ce, Yb or U ions transform the electronic properties of these compounds leading to quasiparticles with masses in excess to 1000 times the bare electron mass. These materials are known as heavy-fermion materials. Two well known heavy – Fermion compounds with Ce based rare earth elements of interest in this thesis are CePt₂Si₂ and CeCu₅In. The effect of substituting Ce with moment bearing Tb or Dy in these two compounds, are reported through measurements of electrical resistivity, magnetic susceptibility and magnetization. The three alloy systems (Ce₁₋ₓREₓ)Pt₂Si₂ (RE = Tb, Dy) and (Ce₁₋ₓTbᵪ)Cu₅In under investigation in the present thesis, was synthesized and characterized by x-ray diffraction. The alloy systems (Ce₁₋ₓREₓ)Pt₂Si₂ (RE = Tb, Dy, 0≤ ᵡ ≤1) formed a single phase in the P4/nmm tetragonal CaBe₂Ge₂ – type structure across the whole series while the (Ce₁₋ₓTbᵪ)Cu₅In alloy system formed a single phase in the Pnma orthorhombic CeCu₆ – type crystal structure up to 40% Ce substitution. The physical properties of these systems is reported and discussed through the measurements of electrical resistivity, magnetic susceptibility and magnetization. The variables of this study are: the doping concentration of Tb or Dy, the applied magnetic field and the sample temperature. Electrical resistivity studies for all the systems revealed coherence effect at Ce – rich alloys (0≤ ᵡ ≤0.2) and single-ion Kondo scattering with further increased RE concentration ( ᵡ ≥ 0.3). The magnetic property studies indicate antiferromagnetic ordering only for the (Ce₁₋ₓREₓ)Pt₂Si₂ alloy system in the concentration range 0.7≤ ᵡ ≤ 1. The present thesis is comprised of six chapters, which are arranged as follows: The first chapter deals with the theoretical background of the physical properties of Ce based intermetallics compounds and alloys. Experimental techniques constitutes chapter II and explains the techniques used in this study. The theoretical overview of the two parent compounds of interest in this thesis (CePt₂Si₂ and CeCu₅In) is presented in chapter III. The fourth and the fifth chapters of this study deals with results and discussion. The thesis is completed with a conclusion in chapter six.

Greater understanding and accurate predictions of structural, thermochemical, and spectroscopic properties of chemical compounds is critical for the advancements of not only basic science, but also in applications needed for the growth and health of the U.S. economy. This dissertation includes new ab initio composite approaches to predict accurate energetics of lanthanide-containing compounds including relativistic effects, and optimization of parameters for semi-empirical methods for transition metals. Studies of properties and energetics of chemical compounds through various computational methods are also the focus of this research, including the C-O bond cleavage of dimethyl ether by transition metal ions, the study of thermochemical and structural properties of small silicon containing compounds with the Multi-Reference correlation consistent Composite Approach, the development of a composite method for heavy element systems, spectroscopic of compounds containing noble gases and metals (ArxZn and ArxAg+ where x = 1, 2), and the effects due to Basis Set Superposition Error (BSSE) on these van der Waals complexes.