ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
MgO–SiO2 precursor gels were prepared by mixing tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS), H2O, and magnesium metal in methanol. Forsterite (Mg2SiO4) and orthoenstatite (MgSiO3) 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 SiO2-rich phase was present, together with crystalline phases. We speculate that the amorphous SiO2-rich phase has an important role in the low-temperature crystallizations of these magnesium silicates. Characterization of the preparation process via liquid-state 29Si nuclear magnetic resonance (NMR) indicated that the breakage of the ≡Si–O–Si≡ bond was caused by the addition of magnesium metal. Solid-state 29Si NMR showed that the Mg–O–Si bond might form in as-prepared specimens.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.1999.tb01718.x
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