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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modelo de Hubbard na caracterização de fases magnéticas em cadeias poliméricas bipartidas generalizadas

Nascimento, Adler da Cruz 25 August 2011 (has links)
Recent research involving magnetic polymers have given very promising results. It is observed in these polymers, the ability to remain magnetized even in the absence of magnetic field which is of great importance to developing new technologies. In order to deepen the knowledge these polymers, in special, its magnetic properties, many researchers have developed theories and methods. In this paper, we use the model developed by Hubbard in 1963. It is a relatively simple model, with important approaches that do not compromise on fundamental analysis, such polymers. With the Hubbard model as a basis, we take a model for the polymer chain in the case of a chain of sub-lattices which one contains the term and the other metal would be the term ligand of the chain. The chain is described as AXBX+1, where A and B are sub-lattices and X gives the size of the chain. We developed this model observing their magnetic properties according to the interaction applied and the number of particles per site building the magnetic phase diagram for different networks AXBX+1. / Recentemente as pesquisas envolvendo polímeros magnéticos têm dado resultados muito promissores. Observa-se nestes polímeros, a capacidade de manteremse magnetizados mesmo na ausência de campo magnético o que é de grande importância para desenvolvimento de novas tecnologias. A fim de aprofundar o conhecimento sobre estes polímeros, em especial, suas propriedades magnéticas, muitos pesquisadores desenvolveram teorias e métodos. Neste trabalho, utilizaremos o modelo desenvolvido por Hubbard em 1963. Trata-se de um modelo relativamente simples, com aproximações importantes que não comprometem análises fundamentais sobre estes polímeros. Com o modelo de Hubbard como base, tomamos um modelo para a cadeia polimérica tratando-se de uma cadeia com sub-redes as quais uma delas contém o termo metálico e a outra teria o termo ligante da cadeia. A cadeia é descrita como AXBX+1, onde A e B são as sub-redes e X dá a dimensão da cadeia. Desenvolvemos este modelo observando suas propriedades magnéticas de acordo com a interação aplicada e o número de partículas por sítio da rede construindo o diagrama de fases magnéticas para diversas redes AXBX+1.
2

Cyanoscorpionates and Transition Metal Complexes.

Johnson, Donald Martin 13 August 2010 (has links) (PDF)
The new dihydrobis(4-cyano-3-tert-butylpyrazolylborate) ligand has been synthesized. Isolated crystals of the thallium complex were collected and structurally characterized by X-ray diffraction. Transition metal complexes of the ligand are currently under investigation.

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