Preparation of Hydrated Strontium Silicates from Silica Hydrogel Isolated from Serpentines and Their Thermal Transformations


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Abstract

Interaction between silica hydrogel isolated from serpentines (Mg(Fe))6[Si4O10](OH)8, sodium hydroxide NaOH, and strontium chloride SrCl2 in aqueous medium was studied by DTA and X-ray powder diffraction (XRD). Stirring of the boiling aqueous suspension prepared from these reagents under the atmospheric pressure for 2 h yields hydrated strontium silicate species: Sr3Si2O7 · 4H2O and Sr3Si2O7 · 3H2O or their mixtures, whose heating to 810–825°C is accompanied by some phase transformations: strontium metasilicate Sr3Si3O9 or strontium orthosilicate Sr2SiO4 is formed after bound water is removed in the range 250–350°C, and strontium silicate SrSiO3 is formed at higher temperatures. Sr2SiO4 single phase is observed upon heat treatment to 700–750°C. The optimal molar ratio of the reagents was found to favor Sr2SiO4 formation.

About the authors

H. A. Beglaryan

Institute of General and Inorganic Chemistry; Erevan State University

Author for correspondence.
Email: Hayk_b@ysu.am
Armenia, Yerevan, 0051; Yerevan, 0025

S. A. Melikyan

Institute of General and Inorganic Chemistry

Email: Hayk_b@ysu.am
Armenia, Yerevan, 0051

A. M. Terzyan

Institute of General and Inorganic Chemistry

Email: Hayk_b@ysu.am
Armenia, Yerevan, 0051

A. R. Isahakyan

Institute of General and Inorganic Chemistry

Email: Hayk_b@ysu.am
Armenia, Yerevan, 0051

N. H. Zulumyan

Institute of General and Inorganic Chemistry

Email: Hayk_b@ysu.am
Armenia, Yerevan, 0051

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