Low Temperature Synthesis of Forsterite Powders by the Geopolymer Technique

Forsterite is a crystalline magnesium silicate with chemical formula Mg₂SiO₄, which has extremely low electrical conductivity that makes it an ideal substrate material for electronics. In this study, forsterite precursors were synthesized with magnesium silicate gels from the mixture of magnesium nitrate solution and various sodium silicate solution by the geopolymer technique. Precursors and heattreated powders were characterized by thermogravimetrical differential thermal analyzer(TG-DTA), X-ray diffractometer(XRD), scanning electron microscopy(SEM), Si magic angle spinning nuclear magnetic resonance(MAS-NMR), transmission electron microscopy(TEM). As the result of analysis about the crystallization behavior by DTA, the synthesized precursors were crystallized in the temperature range of 700℃ to 900℃. The XRD results showed that the gel composition began to crystallize at various temperature. Also, it was found that the sodium orthosilicate based precursors(named as ‘FO’) began to crystallize at above 550℃. The FO peaks were much stronger than sodium silicate solution based precursors(named as ‘FW’), sodium metasilicate based precursors(named as ‘FM’) at 800℃. TEM investigation revealed that the 100㎚ particle sized sample was obtained from FO by heating up to 800℃.

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