ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
The System MgO—Si02—H20 at Temperatures of 150—350°C under Hydrothermal Conditions
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Bratislava 9
Abstract: The mixtures of magnesium oxide and silicon dioxide were prepared
by using various forms of the silicon dioxide. The mixtures with the molar
ratio M/S* between 0.3 — 2.5 were subjected to a hydrothermal process
during 6, 12 and 24 hours and at temperatures of 150, 200, 250, 300 and
350°C. The samples thus obtained were investigated by means of X-ray
diffraction, DTA, electron microscopy, as well as by chemical analysis.
It was found that the first step reaction product was a compound with the
molar ratio M/S = 1.5, regardless the molar ratio of the starting mixture.
This compound formed a gel in which singular crystals could not be
distinguished even by electron microscopy. It was characterized by an
expressive exothermic peak of the DTA curve at 850°C and by a weak
endothermic deflection in the temperature interval between 500— 700°C.
With the molar ratio M/S = 1.0, the formation of serpentine and talc
was found at 300°C and at higher temperatures. With the molar ratio
M/S equal or smaller than 0.75 talc was formed as early as after 24 hours
at 300°C or at the temperatures over 300°C, respectively.
Full paper in Portable Document Format: 237a515.pdf
Chemical Papers 23 (7) 515–520 (1969)
Tuesday, September 27, 2022