• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Master's Dissertation
DOI
10.11606/D.76.1995.tde-02042015-115311
Document
Author
Full name
Cesar Antonio Oropesa Avellaneda
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1995
Supervisor
Committee
Aegerter, Michel Andre (President)
Avaca, Luis Alberto
Gorenstein, Annette
Title in Portuguese
Preparação e caracterização de filmes finos sol-gel de Nb2O5
Keywords in Portuguese
Não disponível
Abstract in Portuguese
Filmes finos de pent6xido de nióbio (Nb2O5) foram obtidos usando a técnica sol-gel a partir de sois preparados com butóxido de nióbio. Após tratamento térmico a 560°C os filmes são cristalinos (fase TT), transparentes, homogêneos e sem defeitos e rachaduras. Os filmes tem excelente propriedades eletrocrômicas com inserção de íons Li+. Eles se tornam de cor azul, com uma variação da transmissão ótica entre 80% (estado de transparência) ate 20% (estado colorido) na faixa de 300 - 1100nm. O processo de inserção e extração de Li+ é reversível e estável eletroquimicamente (testes realizados ate 2000 voltametria cíclicas). A inserção e extração de íons de Li+ foi estudada por técnica de voltametria cíclica e espectroscopia ótica num eletrólito constituído de uma solução 0,1M de perclorato de lítio (LiClO4) dissolvido em carbonato de propileno (PC). A cinética deste processos foi estudada por técnica de cronoamperometria. As caracterizações estruturais foram determinadas por difração de raios-X, retro-espalhamento de Rutheford, e espectroscopia de infravermelho. A morfologia e textura dos filmes foram estudadas usando a técnica de microscopia eletrônica de varredura (SEM)
Title in English
Not availabel
Keywords in English
Not available
Abstract in English
Thin films of niobium. pentoxide (Nb2O5) have been obtained by sol-gel method using sols prepared from Nb pentoxide. After thermal treatment at 560°C, the coatings were found crystalline, transparent, and homogeneous without defects or cracks. The films show excellent electrochromic properties under Li+insertion. The coatings turn deep blue with a variation of the optical transmission of 80% (bleached state) to 20% (colored state) in the spectral range 300-1100nm. The process of Li+ insertion or extraction is reversible and electrochemically stable (tested up to 2000 voltammeter cycles). The electrochromic properties have been studied by electrochemical techniques such as cyclic voltammeter and optical spectroscopy in electrolyte of 0,1M lithium perclorate (LiClO4) dissolved in propylene carbonate (PC). The kinetic process was studied by chronoamperometry technique. The structural characterization has been determined by x-ray difraction, Rutherford backscattering, infrared spectroscopy. Scanning electronic micrography was used to obtain the morphology and texture of the coatings
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
CesarAvellanedaM.pdf (3.30 Mbytes)
Publishing Date
2015-04-06
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
Centro de Informática de São Carlos
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2020. All rights reserved.