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Doctoral Thesis
DOI
10.11606/T.43.1993.tde-13092013-112622
Document
Author
Full name
Keizo Yukimitu
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1993
Supervisor
Committee
Watanabe, Shigueo (President)
Almeida, Adelaide de
Caldas, Linda Viola Ehlin
Figueiredo Neto, Antonio Martins
Pela, Carlos Alberto
Title in Portuguese
Eletrodifusão, absorção óptica e termoluminescência no quartzo e berilo
Keywords in Portuguese
berilo
defeitos
eletrodifusão.
quartzo
termoluminescência
Abstract in Portuguese
No presente trabalho, foi montado um sistema de eletrodifusão para o estudo dos efeitos da substituição de íons alcalinos, presentes no canal estrutural, por íons de hidrogênio (H POT. +), nas propriedades termoluminescentes e ópticas do quartzo. A corrente elétrica de eletrólise apresenta, na parte inicial de aquecimento, um ombro ou pico de corrente. Através da análise do comportamento deste pico e informações obtidas de dados de absorção óptica na região espectral do infravermelho, concluiu-se que o pico presente na curva inicial de eletrólise se deve ao complexo [AL POT. 3+/M POT. +]. As medidas de termoluminescência e absorção óptica na região espectral do visível e ultra-violeta foram feitas em amostras de quartzo eletrodifundidos e não eletrodifundidos e chegou-se à proposição de uma reação envolvendo os alcalinos presentes no canal. Nesta reação, os íons alcalinos fazem o papel de centros armadilhadores de íons de oxigênio O POT. produzidos pela radiação ionizante, e estabilizadores de vacâncias de oxigênio. O aquecimento, em tomo de 300 GRAUS C, provoca a desestabilização desses centros armadilhadores, liberando os íons alcalinos que reagem com os defeitos [ALO IND. 4] POT. 0 emitindo luz TL. Aproveitando a existência de canais estruturais, semelhantes ao quartzo, tentou-se eletrodifundir H POT + no berilo. Através de medidas de termoluminescência e corrente inicial de eletrólise, discute-se a possibilidade da existência do defeito [FE POT. 3+/M POT. +] no berilo.
Title in English
Electrodiffusion, optical absorption and thermoluminescence of quartz and beryl
Keywords in English
beryl
defects
electrodiffusion
Quartz
thermoluminescence
Abstract in English
A system of electrodiffusion was made in the laboratory to investigate effects of exchanging alkali ions, usually present in the structural channels by protons, in the optical and thermoluminescent properties of quartz. In the initial part of heating, the sweeping current presents a peak at about 350 GRAUS C. The analysis of the behaviour of this peak with additional data of optical absorption in the region of infrared, it was concluded that the peak at 350 GRAUS C of the current is due to [AL POT. 3+/M POT. +] system. Thermoluminescence and optical absorption spectra in the visible and ultraviolet light region for swept and unswept quartz were compared. Based on this comparison it was shown that, once irradiated to gama- or X-rays, alkali ions are removed from [AL POT. 3+/ M POT. +] and either couple to o ions or capture electron and become interstitial alkali atom, leaving, further, [ALO IND. 4] POT. 0 hole center. Heating at about 300 GRAUS C electrons from M POT 0 or M POT +O POT recombine with holes in [ALO IND. 4] POT. 0, emitting TL light, besides regrouping Al POT. 3+ and M POT. + to reform [Al POT. 3+/M POT. +] system by coulomb attraction. The electrodiffusion experiment was extended to beryl crystal, because beryl has also structural channels. To explain initial sweeping current behaviour as well as thermoluminescent property a mechanism involving [FE POT. 3+/M POT. +] system is proposed.
 
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Publishing Date
2013-09-13
 
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