Dehydration processes of gyrolite

Yoshihiko Okada; Yonghao Fang; Hideki Ishida; Hirotsugu Nishido

Dehydration processes of gyrolite

Yoshihiko Okada, Yonghao Fang, Hideki Ishida, Hirotsugu Nishido

Environmental Studies

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Abstract

The thermal decomposition processes of natural and synthesized gyrolite, which have a sheet silicate anion structure with Ca/Si molar ratio of 0.66, were compared mainly by ²⁹Si MAS NMR. In the two samples, the silicate anions has the same structure (protonated Q³), however their crystallinity was different. The protonated Q³ structure in both samples decomposed gradually below 800 °C to form nonprotonated monomer (Q⁰) and chain silicate (Q¹ and Q²). Above 900 °C, the natural gyrolite decomposed to pseudo-wollastonite and silica glass, while the synthesized one changed to pseudo-wollastonite and cristobalite via wollastonite. These differences are believed to be caused by the differences in their crystallinity, decomposition rate and the flux effect resulting from the glassification of the impurities.

Original language	English
Pages (from-to)	452-458
Number of pages	7
Journal	Journal of the Ceramic Society of Japan. International ed.
Volume	102
Issue number	5
Publication status	Published - 1994 May 1

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abstract = "The thermal decomposition processes of natural and synthesized gyrolite, which have a sheet silicate anion structure with Ca/Si molar ratio of 0.66, were compared mainly by 29Si MAS NMR. In the two samples, the silicate anions has the same structure (protonated Q3), however their crystallinity was different. The protonated Q3 structure in both samples decomposed gradually below 800 °C to form nonprotonated monomer (Q0) and chain silicate (Q1 and Q2). Above 900 °C, the natural gyrolite decomposed to pseudo-wollastonite and silica glass, while the synthesized one changed to pseudo-wollastonite and cristobalite via wollastonite. These differences are believed to be caused by the differences in their crystallinity, decomposition rate and the flux effect resulting from the glassification of the impurities.",

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N2 - The thermal decomposition processes of natural and synthesized gyrolite, which have a sheet silicate anion structure with Ca/Si molar ratio of 0.66, were compared mainly by 29Si MAS NMR. In the two samples, the silicate anions has the same structure (protonated Q3), however their crystallinity was different. The protonated Q3 structure in both samples decomposed gradually below 800 °C to form nonprotonated monomer (Q0) and chain silicate (Q1 and Q2). Above 900 °C, the natural gyrolite decomposed to pseudo-wollastonite and silica glass, while the synthesized one changed to pseudo-wollastonite and cristobalite via wollastonite. These differences are believed to be caused by the differences in their crystallinity, decomposition rate and the flux effect resulting from the glassification of the impurities.

AB - The thermal decomposition processes of natural and synthesized gyrolite, which have a sheet silicate anion structure with Ca/Si molar ratio of 0.66, were compared mainly by 29Si MAS NMR. In the two samples, the silicate anions has the same structure (protonated Q3), however their crystallinity was different. The protonated Q3 structure in both samples decomposed gradually below 800 °C to form nonprotonated monomer (Q0) and chain silicate (Q1 and Q2). Above 900 °C, the natural gyrolite decomposed to pseudo-wollastonite and silica glass, while the synthesized one changed to pseudo-wollastonite and cristobalite via wollastonite. These differences are believed to be caused by the differences in their crystallinity, decomposition rate and the flux effect resulting from the glassification of the impurities.

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Dehydration processes of gyrolite

Abstract

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