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Master's Dissertation
DOI
10.11606/D.88.2012.tde-15082012-125906
Document
Author
Full name
Alessandro Fernandes
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2012
Supervisor
Committee
Mastelaro, Valmor Roberto (President)
Camargo, Emerson Rodrigues de
Moreira, Mario Lucio
Title in Portuguese
Síntese e caracterização do composto SrTi1-XNbXO3 nanoestruturado
Keywords in Portuguese
Filmes finos.
Fotoluminescência
Nanopartículas
SrTi1-XNbXO3
XANES
Abstract in Portuguese
Amostras nanoestrutradas do sistema 'SR'TI IND.1-x'NB IND.x'O IND.3' na forma de pó contendo até 10 mol % de nióbio foram preparadas através do método dos precursores poliméricos. As propriedades térmicas, estruturais e óticas destas amostras foram caracterizadas através de diferentes técnicas. Os resultados mostram que no limite de concentração de nióbio que foi incorporado a rede da matriz 'SR'TI'O IND.3', ocorreu a formação da solução sólida 'SR'TI IND.1-x'NB IND.x'O IND.3' e que o aumento da quantidade de nióbio leva a uma maior aglomeração das partículas bem como a um aumento na temperatura de cristalização das amostras. Em bom acordo com dados da literatura, uma intensidade fotoluminescente significativa foi somente observada em amostras amorfas ou parcialmente cristalinas. Amostras na forma de filmes finos foram obtidas através da técnica de evaporação por feixe de elétrons. Os dados de difração de raios-X (DRX) mostram que em certas composições, além da fase 'SR'TI'O IND.3', observou-se a presença da fase 'SR'CO IND.3'. Através das técnicas de DRX e Microscopia de força atômica (AFM) foi possível observar que, como no caso das amostras na forma de pó, o aumento da concentração de nióbio inibe o processo de cristalização da amostra. Medidas da resistência elétrica mostraram que todas as amostras, independente da concentração de nióbio, apresentam valores elevador de resistência, da ordem de '10 POT.15' 'ômega' . Este valor, muito acima do esperado e do observado na literatura, inviabilizou a medidas de sensibilidade dos filmes a diferentes tipos de gases.
Title in English
Synthesis and Characterization of SrTi1-XNbXO3 Compound Nanostructured
Keywords in English
Nanoparticles
Photoluminescence
SrTi1-XNbXO3
Thin films
XANES
Abstract in English
Nanostructured 'SR'TI IND.1-x'NB IND.x'O IND.3' samples in a powder form containing up to 10 mol% of niobium have been prepared by the polymeric precursor method. The thermal, structural and optical properties of these samples were characterized by different techniques. The results show that in the limit of concentration of niobium added to the samples, the dopant was incorporated into the 'SR'TI'O IND.3' matrix lattice forming a 'SR'TI IND.1-x'NB IND.x'O IND.3' solid solution. The increasing on the amount of niobium leads to an increased agglomeration of the particles as well as an increase in the crystallization temperature of the samples. In good agreement with the literature data, a significant photoluminescence intensity was only observed in amorphous or partially crystalline samples. Samples in the form of thin films were obtained using the electron beam evaporation technique. X-ray diffraction (XRD) show that in certain compositions, beyond the 'SR'TI'O IND.3' phase, it was also observed the presence of phase 'SR'CO IND.3' phase. Through the XRD and Atomic Force Microscope (AFM) results, it has been observed that, as in the case of the samples in powder form, the concentration of niobium inhibits the crystallization process of the sample. Electrical resistance measurements showed that all samples, independent of the concentration of niobium, present higher values of resistance of the order of '10 POT.15' 'ômega' . This value is much higher than expected and reported in the literature and does not allowed to measure the sensibility of thin films to different species of gases.
 
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Aledissmestrado.pdf (3.31 Mbytes)
Publishing Date
2012-09-06
 
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