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Master's Dissertation
DOI
10.11606/D.54.1983.tde-21052007-150715
Document
Author
Full name
Vanderlei Salvador Bagnato
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1983
Supervisor
Committee
Zilio, Sergio Carlos (President)
Carmo, Luiz Carlos Scavarda do
Hipolito, Oscar
Title in Portuguese
Espectroscopia no infravermelho e Raman do aluminato de gadolineo puro e dopado com íons de terras raras
Keywords in Portuguese
Aluminato de gadolineo
Espectro IR
Espectro Raman
Abstract in Portuguese
Realizamos medidas de transmissão no infravermelho (médio e distante) e espelhamos Raman de amostras de GdAlO3 puras e dopadas com Eu+3 para estudarmos as bandas de absorção de fonons K=0 e as transições eletrônicas nos íons Eu+3. Conhecendo-se a simetria do GdAlO3 (D162h) pudemos, utilizando o método da correlação, calcular o número e a simetria dos modos vibracionais, bem como sua classificação em internos e externos. Os resultados experimentais mostram boa concordância com os teóricos e revelam que o GdAlO3 apresenta três regiões distintas no infravermelho, compostas de várias bandas de absorção. Os modos internos estão em torno de 670cm-1 (estiramento) e 480cm-1 (flexão) enquanto que os modos externos localizam-se em torno de 200cm-1. A interação dos estados eletrônicos do Eu+3 com o campo cristalino do GdAlO3 foi estudada inicialmente supondo um campo de simetria Oh e depois introduzindo a distorção ortorrômbica (Cs) de uma maneira perturbativa. Pudemos verificar que a dita distorção levanta totalmente a degenerescência dos níveis 7FJ (J=0,1,...,6) e torna as transições 7F07FJ permitidas.
Title in English
Raman and infrared spectrometry of gadolinium aluminates pure and doped
Keywords in English
Gadolinium aluminate
Infrared
Raman
Abstract in English
IR and Raman measurements were carried out in pure and Eu+3 - doped GdAlO3 with the purpose of understanding their K=O phonom modes and the Eu+3 electronic transitions. Starting from the GdAlO3 symmetry, (D162h) the correlation method allows the classification of the number and symmetries of the modes, as well their assignment as either internal or external. Experimental and theoretical results are in good agreement and show three well defined absorption bands in GdAlO3. The internal modes are found to be located around 670cm-1 (stretching) and 480cm-1 (bending), while the external modes are around 200cm-1. The interaction of Eu+3 electronic states with the GdAlO3 crystal fields were studied by taking into account small perturbative orthorrombic (Cs) distorcion on a crystal field with symmetry Oh. This small distortion lifts completely the degeneracy of the 7FJ (J=0,1,...,6) levels and allows the 7F07FJ transitions.
 
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VanderleiBagnato.pdf (4.77 Mbytes)
Publishing Date
2007-06-29
 
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