Investigação das propriedades ópticas, elétricas e estruturais em ametista
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Data
2011-08-05
Autores
Russo, Fabricio Trombini [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Propriedades elétricas, ópticas e estruturais de SiO2 na variedade Ametista foram investigadas, utilizando as técnicas de Difração de Raios X, Absorção Óptica e Corrente de Despolarização Termicamente Estimulada (CDTE), tanto com procedimento convencional como Fotoinduzido (CDTEFI). objetivo principal, as técnicas de CDTE buscam a relação entre a relaxação observada, através das bandas de corrente obtidas na despolarização do material, e as impurezas no Quartzo, visto que os cristais de Quartzo mais perfeitos têm traços de ferro, lítio, sódio, potássio, alumínio, manganês e titânio. Adicionalmente às medidas de CDTE, as técnicas de Difração de Raios X e Absorção Óptica foram utilizadas para verificação da estrutura e bandas de aborção do material, respectivamente. Os difratogramas de Raios X mostraram que as amostras utilizadas exibem boa pureza, pois os picos correspondem aos dados catalogados de Quartzo puro. Os dados de absorção óptica permitiram tanta a identificação de bandas de absorção características na Ametista como uma relação com as medidas de CDTE e CDTEFI, ou seja, uma correlação entre as bandas de absorção para determinados comprimentos de onda, e a incidência de luz com comprimentos próximos a essas bandas. Foram realizadas medidas de CDTEFI com variação da potência de incidência do laser de Ar+ da ordem de 250 mW nas linhas de 488 nm. Os resultados das medidas de CDTE, CDTEFI e de Absorção Óptica analisados em conjunto, permitiram comprovar a presença de defeitos formados por íons de Fe3+ e Fe4+ na estrutura da Ametista, bem como sugerir que estes defeitos, além de participarem da estrutura como formadores dos centros de cor, são elementos contribuintes na formação fas bandas de CDTE, fazendo, portanto, com que estas bandas sejam afetadas pela incidência de luz monocromática do laser de Ar+ nas amostras...
Electrical, optical and structural properties of SiO2 in the amethyst form have been investigated, using techniques such as X-ray diffraction, optical absorption and thermally stimulated depolarization current (TSDC) in the conventional procedure as well as in the photo-induced case (PITSDC). Main objective in this work, TSDC techniques aim to analyze the relationship of observed relaxation phenomena, through the obtained current bands in the material depolarization, with quartz impurities, because even the most perfect quartz crystals present traces of iron lithium, sodium, potassium, aluminum, manganese and titanium. In addition to TSDC measurements, X-ray diffraction and optical absortion techniques have been used to verify the structure and the material absorption bands, respectively. X-ray diffractograma show that samples exhibits good purity, since the peaks correspond to published data for pure quartz. optical absorption data allow identifying the characteristics bands of amethyst as well as to relate them with TSDC and PITSDC measurements, which measurements, which means that there is a relationship between an absorption band at some fixed wavelength and light irradiation with wavelengths close to these bands. PITSDC was carried out using an Ar+ laser with varying power of about 250 mW, 500 mW and 610mW tuned at lines 488 nm and 541 nm. TSDC and PITSDC results, along with optical absorption data, when analyzed in conjunction, allow the verification of defects formed by Fe3+ and Fe4+ ions in the amethyst structure, as well as the suggestion that these defects, besides the participation in the amethyst structure as color centers, also play a role in the formation of TSDC bands, contributing for the effect of monochromatic light irradiation of an Ar+ laser on these bands (PITSDC). In this measurement, a redution of up to 71.1% comparede to conventional... (Complete abstract click electronic access below)
Electrical, optical and structural properties of SiO2 in the amethyst form have been investigated, using techniques such as X-ray diffraction, optical absorption and thermally stimulated depolarization current (TSDC) in the conventional procedure as well as in the photo-induced case (PITSDC). Main objective in this work, TSDC techniques aim to analyze the relationship of observed relaxation phenomena, through the obtained current bands in the material depolarization, with quartz impurities, because even the most perfect quartz crystals present traces of iron lithium, sodium, potassium, aluminum, manganese and titanium. In addition to TSDC measurements, X-ray diffraction and optical absortion techniques have been used to verify the structure and the material absorption bands, respectively. X-ray diffractograma show that samples exhibits good purity, since the peaks correspond to published data for pure quartz. optical absorption data allow identifying the characteristics bands of amethyst as well as to relate them with TSDC and PITSDC measurements, which measurements, which means that there is a relationship between an absorption band at some fixed wavelength and light irradiation with wavelengths close to these bands. PITSDC was carried out using an Ar+ laser with varying power of about 250 mW, 500 mW and 610mW tuned at lines 488 nm and 541 nm. TSDC and PITSDC results, along with optical absorption data, when analyzed in conjunction, allow the verification of defects formed by Fe3+ and Fe4+ ions in the amethyst structure, as well as the suggestion that these defects, besides the participation in the amethyst structure as color centers, also play a role in the formation of TSDC bands, contributing for the effect of monochromatic light irradiation of an Ar+ laser on these bands (PITSDC). In this measurement, a redution of up to 71.1% comparede to conventional... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Ametista, Quartzo, Ametista - Propriedades elétricas, Amethyst - Electrical properties
Como citar
RUSSO, Fabricio Trombini. Investigação das propriedades ópticas, elétricas e estruturais em ametista. 2011. 113 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências, 2011.