Caracterização de impurezas estruturais e de centros de defeitos relacionados ao A1 e OH quartzo natural

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

Characterization of lattice impurities and study of AI and H defects centers have conducted on natural quartz through a variety of experiments. For this purpose, about thirty samples of natural quartz were assembled from fourteen mines with known localities in Brazil. "The concentrations of Al, Fe , Li, Na e K have evaluated by atomic absorption spectroscopy C AAS) . Beforehand, most part of fluid inclusions were removed by means of quench-leach procedure. The concentration of OH groups and the intens1ties of AI-OH and Li-OH defect centers have estimated by IR spectroscopy. In this study natural quartz samples were subjected to ?-irradiation at room temperature with a dose of 20x106 Roentgen. Resulting darkening degree (?D) associated with AI-h paramagnetic centers has evaluated by UV-VIS spectroscopy. Its become clear that ?d and the ratio between Li and Al contents are related to geological formation of natural quartz. AI-OH and AI-Li centers are the principal AI-relating species observed in as-grown natural quartz and theirs intensities depend on OH and Li concentrations. Formation of Al-h centers are approximately proportional to AI-Li centers and inversely proportional to Al-OH centers. After y-irradiation. its were observed a drastically reduction in Li-OH and a small enhancement. in AI ?OH absorption intensities. Its were confirmed the relationships between Ai and Li contents and also between Na and OH contents

ASSUNTO(S)

quartzo engenharia mecanica

ACESSO AO ARTIGO

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