engleski

On the sensitivity of positron lifetime spectroscopy to the stages of crystallization of LTA type zeolite

Positron annihilation techniques (PAT) are extensively used for structural investigation of solids also including porous media where positron lifetime (LT) data have shown the coexistence of annihilation modi with long lifetime components. Our aim was to study the possible influence of the progress of crystallization on the long lifetimes and their intensities. LTA type zeolites were prepared and their synthesis was stopped at various degrees of crystallization. LT measurements were performed at room temperature in air and in vacuum on samples with various gels containing exchanged directing cations. The results show the presence of long components. A correlation with crystallinity and the type of exchanged ion is also indicated. Particularities of LT distributions (recorded with a short and long time range setting simultaneously) on evacuated and heat-treated samples will be discussed.

positron annihilation; zeolites

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