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Low‐Temperature Crystallization of Forsterite and Orthoenstatite
Author(s) -
Ban Takayuki,
Ohya Yutaka,
Takahashi Yasutaka
Publication year - 1999
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1999.tb01718.x
Subject(s) - forsterite , crystallization , amorphous solid , magnesium , materials science , chemical engineering , phase (matter) , metal , breakage , inductively coupled plasma , analytical chemistry (journal) , mineralogy , chemistry , crystallography , metallurgy , organic chemistry , plasma , composite material , engineering , physics , quantum mechanics
MgO–SiO 2 precursor gels were prepared by mixing tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS), H 2 O, and magnesium metal in methanol. Forsterite (Mg 2 SiO 4 ) and orthoenstatite (MgSiO 3 ) were crystallized from their precursors at temperatures as low as 500° and 700°C, respectively. The chemical compositions of the crystallized phases were richer in MgO content than those of the starting materials. Inductively coupled plasma analysis showed that an amorphous SiO 2 ‐rich phase was present, together with crystalline phases. We speculate that the amorphous SiO 2 ‐rich phase has an important role in the low‐temperature crystallizations of these magnesium silicates. Characterization of the preparation process via liquid‐state 29 Si nuclear magnetic resonance (NMR) indicated that the breakage of the ≡Si–O–Si≡ bond was caused by the addition of magnesium metal. Solid‐state 29 Si NMR showed that the Mg–O–Si bond might form in as‐prepared specimens.