Ba交換ゼオライトAからの単斜晶セルシアンの合成

概要

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Two kinds of zeolites with different crystal structures with the composition of BaO・Al_2O_3・2SiO_2・xH_2O prepared by an ion-exchange technique were used as a precursor of celsian. The difference between the zeolite structures resulted in the difference in modifications of celsian obtained through a heating treatment. Ba-exchanged zeolite A became an amorphous material at 300℃ with dehydration, and then generates a small amount of monocelsian in the amorphous material at 500℃. When successively at 950℃ for 1 h, hexacelsian formed in addition to the previously produced monocelsian. A single phase of monocelsian was obtained finally by heating at 1500℃ for 8 h. The specimen heated at 1700℃, however, became a single phase of hexacelsian, owing to monocelsian-to-hexacelsian phase transformation. The structure of Ba-exchanged Linde F zeolite collapsed at 300℃ with dehydration, and only hexacelsian formed at temperatures above 980℃. The reason for the formation of monocelsian only from Ba-exchanged zeolite A was explained in terms of the similarity in framework structures of zeolite A and monocelsian.
社団法人日本セラミックス協会の論文
2002-03-01