Propriedades e mecanismos de cintilação dos materiais 'GD''AL''O IND.3' e ('GD''LU')'AL''O IND.3' dopados com 'EU POT. 3+', 'TB POT. 3+' e 'PR POT. 3+'
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Data
2011-04-29
Autores
Oliveira, Higor Henrique de Souza [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Cintiladores são materiais capazes de absorver radiações de alta energia e convertê-las eficientemente em radiações ultravioleta ou visível. Avanços significativos na eletrônica de detecção dessas radiações motivaram as pesquisas visando à busca por novos materiais cintiladores de alta eficiência e à maior compreensão do mecanismo de cintilação. Nesse contexto, os compostos de matriz GdAlO3 e Gd1-xLuxAlO3 dopados com Eu3+, Tb3+ ou Pr3+ são materiais cintiladores promissores, pois apresentam alta densidade, elevados valores de coeficiente de atenuação de massa e propriedades espectroscópicas relevantes como emissão intensa, tempo de vida de mili ou microssegundos e transferência de energia a partir dos íons Gd3+ para os ativadores. Neste trabalho, foi investigada a preparação dos cintiladores GdAlO3 e Gd1-xLuxAlO3 nominalmente puros e dopados com Eu3+, Tb3+ e Pr3+ através do método dos precursores poliméricos (método Pechini) e suas propriedades estruturais e espectroscópicas (fotoluminescência e luminescência com excitação por raios X) foram investigadas. O perfil espectral de emissão das amostras de GdAlO3 dopadas com Eu3+ evidencia a ocupação de dois sítios distintos pelos íons dopantes quando em concentrações superiores a 1,0%-mol, provavelmente devido à distribuição não homogênea dos íons na matriz. A transferência de energia Gd3+→Ln3+ foi evidenciada pela espectroscopia de fotoluminescência e é um processo importante no mecanismo de cintilação desses materiais, como evidenciado pela comparação das medidas espectroscópicas de fotoluminescência e luminescência com excitação por raios X das amostras de GdAlO3:Pr3+. Com a incorporação de Lu3+ na matriz de GdAlO3, a intensidade de emissão aumenta até a concentração de 10%-mol de Lu3+, decrescendo...
Scintillators materials are compounds that can absorb ionizing radiations and efficiently convert them into UV-VIS radiations. Despite of impressive advances in the technology of direct detection, the search for new scintillators materials with high efficiency and for the precise understanding of the scintillation mechanism is still the focus of research in this area. In this context, the compounds GdAlO3 and Gd1-xLuxAlO3 doped with Eu3+, Tb3+ and Pr3+ are promising scintillators materials, since they have high density, high values of mass attenuation coefficient and relevant spectroscopic properties, such as bright emission, lifetime of milli or microseconds and the energy transfer from Gd3+ ions to the activators. This work describes the preparation of GdAlO3 and Gd1-xLuxAlO3 nominally pure and doped with Eu3+, Tb3+ e Pr3+ by the polymeric precursor method (Pechini method) and the study of their structural and spectroscopic (photoluminescence and X-rays excited optical luminescence) properties. Emission spectral profile of Eu3+-doped GdAlO3 indicates the occupation of two different sites by the dopant ions when the concentration is higher than 1.0 mol-%, probably due to inhomogeneous distribution of ions in the host. The energy transfer Gd3+→Ln3+ was evidenced by photoluminescence spectroscopy and is an important process in the scintillation mechanism of these materials, as showed by comparison of spectroscopic measurements of photoluminescence and X-rays excited optical luminescence of GdAlO3:Pr3+ sample. The emission intensity increases by incorporating Lu3+ in the GdAlO3 host until the Lu3+ concentration of 10 mol-%, decreasing at higher concentrations. This behavior is probably assigned to the balance between increasing the absorption of X-rays and the reduction of the transfer process from Gd3+ ions with increasing concentration of... (Complete abstract click electronic access below)
Scintillators materials are compounds that can absorb ionizing radiations and efficiently convert them into UV-VIS radiations. Despite of impressive advances in the technology of direct detection, the search for new scintillators materials with high efficiency and for the precise understanding of the scintillation mechanism is still the focus of research in this area. In this context, the compounds GdAlO3 and Gd1-xLuxAlO3 doped with Eu3+, Tb3+ and Pr3+ are promising scintillators materials, since they have high density, high values of mass attenuation coefficient and relevant spectroscopic properties, such as bright emission, lifetime of milli or microseconds and the energy transfer from Gd3+ ions to the activators. This work describes the preparation of GdAlO3 and Gd1-xLuxAlO3 nominally pure and doped with Eu3+, Tb3+ e Pr3+ by the polymeric precursor method (Pechini method) and the study of their structural and spectroscopic (photoluminescence and X-rays excited optical luminescence) properties. Emission spectral profile of Eu3+-doped GdAlO3 indicates the occupation of two different sites by the dopant ions when the concentration is higher than 1.0 mol-%, probably due to inhomogeneous distribution of ions in the host. The energy transfer Gd3+→Ln3+ was evidenced by photoluminescence spectroscopy and is an important process in the scintillation mechanism of these materials, as showed by comparison of spectroscopic measurements of photoluminescence and X-rays excited optical luminescence of GdAlO3:Pr3+ sample. The emission intensity increases by incorporating Lu3+ in the GdAlO3 host until the Lu3+ concentration of 10 mol-%, decreasing at higher concentrations. This behavior is probably assigned to the balance between increasing the absorption of X-rays and the reduction of the transfer process from Gd3+ ions with increasing concentration of... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Química inorgânica, Luminescencia, Inorganic chemistry, Luminescence
Como citar
OLIVEIRA, Higor Henrique de Souza. Propriedades e mecanismos de cintilação dos materiais 'GD''AL''O IND.3' e ('GD''LU')'AL''O IND.3' dopados com 'EU POT. 3+', 'TB POT. 3+' e 'PR POT. 3+'. 2011. 101 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química, 2011.