PREPARATION AND CHARACTERIZATION OF FORSTERITE (MG2SIO4) AEROGELS

2MgO . SiO2 gels were prepared from alkoxide precursors using differen t prehydrolysis conditions for TEOS, and dried supercritically. The re sultant powders were subjected to heat treatments to 1200 degrees C, a nd the formation of the forsterite crystal phase was studied. The powd ers were characterised using differential thermal analysis, thermograv imetric analysis, BET surface area analysis, X-ray diffraction and tra nsmission electron microscopy. Formation of forsterite between 795 and 805 degrees C indicated a high degree of homogeneity in the gels, alt hough the initial formation of MgO at 490 degrees C suggested that the re were some regions which were MgO or SiO2 rich. Surface areas betwee n 207 and 340 m(2) g(-1) were observed. TEM revealed loosely packed ag glomerates with primary particle sizes between 10 and 15 nm. On heatin g to 1200 degrees C the primary particle size increased to 200 nm, alt hough the average agglomerate size did not increase significantly. (C) 1998 Elsevier Science B.V. All rights reserved.