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Master's Dissertation
DOI
https://doi.org/10.11606/D.76.1997.tde-14082009-123550
Document
Author
Full name
Fábio Becker Guedes
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1997
Supervisor
Committee
Bonagamba, Tito Jose (President)
Faria, Roberto Mendonça
Moraga, Guillermo Antonio Gonzalez
Title in Portuguese
Estudo dos compostos intercalados Lix MoS2 e Lix(POE)y MoS2 utilizando-se espectroscopia de alta resolução e relaxação em sólidos por RMN
Keywords in Portuguese
Compostos intercalados
Condutores iônicos
RMN do estado sólido
Abstract in Portuguese
Compostos intercalados de lítio sac considerados materiais apropriados para eletrodos de baterias recarregáveis de lítio. O conhecimento das taxas de difusão, assim como os mecanismos relacionados com a mobilidade dos íons nos espaços interlaminares são portanto pertinentes para a caracterização das propriedades deste tipo de compostos. Investigações por ressonância magnética nuclear tem um papel ativo no estudo do comportamento dinâmico e estrutural destes compostos de lítio sólidos. Por essa razão este trabalho e baseado nos espectros de RMN obtidos entre 150K e 400K em um campo de 2T. As larguras de linha do 1H e do Li+ foram medidas a partir da transformada de Fourier dos FIDs resultantes da excitação da amostra por um pulse π/2. O desacoplamento de 1H foi utilizado, quando necessário, para excluir a contribuição dipolar magnética a destes núcleos a largura de linha do 7Li. Os tempos de relaxação spin-rede para os núcleos 7Li e 1H foram obtidos utilizando-se o método de inversão-recuperação. A partir destas medidas, diversos parâmetros dinâmicos e estruturais destes compostos foram encontrados como: energias de ativação, tempos de correlação e coeficientes de difusão dos íons lítio.
Title in English
Study of intercaled compounds LixMoS2 and Lix(POE)yMOS2 using high resolution spectroscopy and relaxation in solids by NMR.
Keywords in English
Intercaled compounds
Ionic conductors
Solid state NMR
Abstract in English
Lithium intercalation compounds are considered suitable materials for electrodes in rechargeable lithium batteries. The knowledge of diffusion rates as well as of mechanistic features related with the mobility of ions in the interlamellar spaces is therefore relevant for the regulation of the properties of this kind of compounds. Nuclear magnetic resonance investigations have played an active role in the study of the dynamic and structural behavior of these solid lithium compounds. For this reason this work is based on NMR spectra recorded between 150K and 400K at 2T. The 1H and Li+ linewidths were measured from the Fourier transform of the FIDs following a π/2 excitation. IH decoupling was used, when necessary, to exclude the magnetic dipolar contribution of this nucleus to the 7Li linewidth. The 7Li and 1H spin-lattice relaxation time T1 were measured using the inversion-recovery method. Several dynamic and structural NMR parameters were obtained from these NMR measurements like activation energies, correlation times and diffusion coefficients.
 
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Publishing Date
2009-08-31
 
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