Avaliação das propriedades luminescentes de cintiladores baseados em oxihaletos de gadolínio GdOX:Eu3+ (X = F-, Cl- e Br-)
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Data
2018-04-26
Autores
Krauser, Maike de Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho realizou-se a síntese dos oxihaletos de gadolínio GdOX (X = F-, Cl- e Br-), nominalmente puros e dopados com 1% at. com íons Eu3+, a fim de avaliar as propriedades luminescentes e de cintilação, por meio de excitação de raios X. Para a obtenção dos materiais, utilizou-se como precursor o método de decomposição térmica da ureia, tratando as amostras termicamente a 900 oC durante três horas em atmosfera dinâmica na presença do sal de amônio referente a cada um dos halogênios ou pela presença nas proporções 1:1, 1:10, 1:100 de Metal: NH4X (X = F-, Cl- e Br-) durante a precipitação. As fases de interesse foram obtidas e confirmadas por meio de difração de raios X, com a presença de fases espúrias para a amostra GdFO. Por microscopia eletrônica de varredura observou-se que as amostras apresentam partículas de morfologia variada e tamanhos micrométricos. Por meio da espectroscopia de fotoluminescência com excitação no ultravioleta, observaram-se os perfis espectrais das amostras dopadas em 1% de íons Eu3+, pode-se distinguir diferentes fases presentes na amostra GdFO, e os perfis de emissão das amostras GdOCl e GdOBr com a presença das transições 5D0 7FJ J = 0, 1, 2, 3 e 4, referentes às transições intraconfiguracionais f-f dos íons Eu3+, assim como a existência de transferências de carga e de energia Gd3+ Eu3+, quando a excitação ocorre nas transições dos íons Gd3+. Por meio da espectroscopia de luminescência com excitação de raios X, observou-se que os materiais apresentam perfil espectral referentes a fase de interesse. As amostras apresentaram características distintas nas curvas de dano de radiação e na variação da intensidade de emissão em relação a temperatura. As amostras não apresentam grandes alterações na capacidade de absorção de radiação ionizante e, mesmo assim, a amostra GdOCl:Eu3+ apresenta uma intensidade de emissão, aproximadamente, cinco vezes maior que as amostras GdFO:Eu3+ e GdOBr:Eu3+.
In this work it was performed the synthesis of the gadolinium oxyhalides GdOX (X = F-, Cl- e Br-), nominally pure and doped with 1% at. with ions Eu3+, in order to evaluate the luminescent and scintillation properties, through X ray excitation. In order to obtain the materials, it was utilized as precursor the thermal decomposition of urea method, treating the samples thermally to 900 °C during three hours in dynamic atmosphere in the presence of ammonium salt regarding to each one of the halogens or by the presence in the proportions 1:1, 1:10, 1:100 of Metal: NH4X (X = F-, Cl- e Br-) during the precipitation. The interest phases were obtained and confirmed through X ray diffraction, with the presence of spurious phases for the sample GdFO. By scanning electron microscopy, it was observed that the samples present particles of varied morphology and micrometric sizes. Through the photoluminescence spectroscopy with excitation in the ultraviolet, it was possible to distinguish different phases in the GdFO sample, and the emission profiles of the samples GdOCl and GdOBr with the presence of the transitions 5D0 7FJ J = 0, 1, 2, 3 e 4, regarding to the intraconfiguration transitions f-f of the ions Eu3+, as well as the existence of charge and energy transfer Gd3+ Eu3+, when the excitation occurs in the ions transitions Gd3+. Through the luminescence spectroscopy with X ray excitation, it was observed that the materials have a spectral profile related to the phase of interest. The samples presented different characteristics in the radiation damage curves and the variation of the emission intensity regarding to the temperature. The samples do not present major changes in the absorption capacity of ionizing radiation, and yet the GdOCl:Eu3+ sample has an emission intensity approximately five times higher than the GdFO:Eu3+ and GdOBr:Eu3+ samples.
In this work it was performed the synthesis of the gadolinium oxyhalides GdOX (X = F-, Cl- e Br-), nominally pure and doped with 1% at. with ions Eu3+, in order to evaluate the luminescent and scintillation properties, through X ray excitation. In order to obtain the materials, it was utilized as precursor the thermal decomposition of urea method, treating the samples thermally to 900 °C during three hours in dynamic atmosphere in the presence of ammonium salt regarding to each one of the halogens or by the presence in the proportions 1:1, 1:10, 1:100 of Metal: NH4X (X = F-, Cl- e Br-) during the precipitation. The interest phases were obtained and confirmed through X ray diffraction, with the presence of spurious phases for the sample GdFO. By scanning electron microscopy, it was observed that the samples present particles of varied morphology and micrometric sizes. Through the photoluminescence spectroscopy with excitation in the ultraviolet, it was possible to distinguish different phases in the GdFO sample, and the emission profiles of the samples GdOCl and GdOBr with the presence of the transitions 5D0 7FJ J = 0, 1, 2, 3 e 4, regarding to the intraconfiguration transitions f-f of the ions Eu3+, as well as the existence of charge and energy transfer Gd3+ Eu3+, when the excitation occurs in the ions transitions Gd3+. Through the luminescence spectroscopy with X ray excitation, it was observed that the materials have a spectral profile related to the phase of interest. The samples presented different characteristics in the radiation damage curves and the variation of the emission intensity regarding to the temperature. The samples do not present major changes in the absorption capacity of ionizing radiation, and yet the GdOCl:Eu3+ sample has an emission intensity approximately five times higher than the GdFO:Eu3+ and GdOBr:Eu3+ samples.
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Palavras-chave
Luminescência, Cintiladores, Radiação ionizante, Espectroscopia eletrônica, Európio