Síntese e estudo de ca2al2sio7 dopado com terras raras e sua possível aplicação na dosimetria por termoluminescência
Date
2022-11-14
Authors
Fiorini, Giovanni Gatti [UNIFESP]
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Cano, Nilo Francisco [UNIFESP]
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Trabalho de conclusão de curso de graduação
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Abstract
Este trabalho tem como objetivo sintetizar o cristal Ca2Al2SiO7 dopado com terras raras
pelo método de reação do estado sólido e realizar o estudo das propriedades
termoluminescentes, a fim de analisar uma possível aplicabilidade como dosímetro de radiação
por termoluminescência.
Por meio do método de reação do estado sólido foram sintetizados pastilhas de silicato de
cálcio e alumínio puras e dopadas com Ce, Eu, Er, nas concentrações de 1%. O Cálculo utilizado
na síntese levou em conta o total de valências dos reagentes do Ca2Al2SiO7, por meio de sua
composição estequiométrica, misturadas e submetidas a temperaturas de 1300 a 1400°C.
As pastilhas foram irradiadas com raios gama para indução TL, para gerar posteriormente
alguns defeitos pontuais nas amostras, com a representação da curva TL do material puro e
dopado com terras raras foi possível notar que no procedimento de irradiação, a curva TL,
apresenta um pico largo em cerca de 220°C, e a amostra com concentração de 1% Ce demonstra
uma alta sensibilidade à dose, em comparação com as outras amostras dopadas com Eu e Er.
Também análises de repetibilidade foram realizadas com objetivo de observar a
variação da intensidade do pico luminescente, então uma amostra com 1% Ce recebeu
irradiação com 5 Gy, e a leitura foi realizada por um leitor TL, o processo foi realizado onze
vezes, apresentando uma boa repetibilidade.
Quanto a investigação da estrutura da amostra de silicato de cálcio e alumínio, este foi
realizado por meio de difratogramas utilizando o método de difração de raios X (DRX), de
acordo com a análise realizada dos difratogramas, os picos seguem um padrão característico em
32°, seguindo o padrão da curva de espectro do Ca2Al2SiO7.
Na literatura não encontram-se muitos estudos a respeito do Ca2Al2SiO7, no que diz
respeito a dosimetria, esse trabalho evidencia que entre as terras raras (Ce, Eu, Er), a que mais
proporcionou uma intensidade TL foi a amostra com 1% de Ce, na ordem de 10².
This work has as objective to synthesize Ca2Al2SiO7 crystal doped with rare earths by the solid state reaction method and study thermoluminescent properties, and also to analyze a possible applicability as a thermoluminescence radiation dosimeter. Through the solid state reaction method, pure calcium aluminum silicate pellets doped with Ce, Eu, Er, in concentrations of 1% were synthesized. The calculation used in the synthesis took into account the total valence of the reactants of Ca2Al2SiO7, through its stoichiometric composition, mixed and submitted to temperatures of 1300 to 1400°C. The pellets were irradiated with gamma rays for TL induction, to subsequently generate some point defects in the samples, with the representation of the TL curve of the pure and rare earth doped material it was possible to note that in the irradiation procedure, the TL curve, presents a broad peak at about 220°C, and the sample with a concentration of 1% Ce shows a high dose sensitivity, compared to the other samples doped with Eu and Er. Also repeatability analyses were performed to observe the variation of the intensity of the luminescent peak, so a sample with 1% Ce received irradiation with 5 Gy, and the reading was performed by a TL reader, the process was performed eleven times, presenting a good repeatability. As for the investigation of the structure of the calcium alumium silicate sample, this was carried out by means of diffractograms using the X-ray diffraction method (XRD), according to the analysis of the diffractograms, the peaks follow a caracteristic pattern at 32º, following the pattern of the spectrum curve of Ca2Al2SiO7. In the literature there are not many studies about Ca2Al2SiO7, with respect to dosimetry, this work shows that among the rare earths (Ce, Eu, Er), the one that provided the highest TL intensity was the sample with 1% Ce, in the order of 10².
This work has as objective to synthesize Ca2Al2SiO7 crystal doped with rare earths by the solid state reaction method and study thermoluminescent properties, and also to analyze a possible applicability as a thermoluminescence radiation dosimeter. Through the solid state reaction method, pure calcium aluminum silicate pellets doped with Ce, Eu, Er, in concentrations of 1% were synthesized. The calculation used in the synthesis took into account the total valence of the reactants of Ca2Al2SiO7, through its stoichiometric composition, mixed and submitted to temperatures of 1300 to 1400°C. The pellets were irradiated with gamma rays for TL induction, to subsequently generate some point defects in the samples, with the representation of the TL curve of the pure and rare earth doped material it was possible to note that in the irradiation procedure, the TL curve, presents a broad peak at about 220°C, and the sample with a concentration of 1% Ce shows a high dose sensitivity, compared to the other samples doped with Eu and Er. Also repeatability analyses were performed to observe the variation of the intensity of the luminescent peak, so a sample with 1% Ce received irradiation with 5 Gy, and the reading was performed by a TL reader, the process was performed eleven times, presenting a good repeatability. As for the investigation of the structure of the calcium alumium silicate sample, this was carried out by means of diffractograms using the X-ray diffraction method (XRD), according to the analysis of the diffractograms, the peaks follow a caracteristic pattern at 32º, following the pattern of the spectrum curve of Ca2Al2SiO7. In the literature there are not many studies about Ca2Al2SiO7, with respect to dosimetry, this work shows that among the rare earths (Ce, Eu, Er), the one that provided the highest TL intensity was the sample with 1% Ce, in the order of 10².
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Citation
FIORINI, Giovanni Gatti. Síntese e estudo de ca2al2sio7 dopado com terras raras e sua possível aplicação na dosimetria por termoluminescência. 2022. 37 f. Trabalho de conclusão de curso (Graduação em Bacharelado Interdisciplinar em Ciência e Tecnologia do Mar) - Instituto do Mar, Universidade Federal de São Paulo, Santos, 2022.