Preparation of barium hexa-aluminate aerogel
Barium hexa-aluminate (BaO · 6Al2O3) aerogels were prepared using a supercritical drying method and their properties examined. A barium hexa-aluminate aerogel prepared from a double alkoxide of barium and aluminum showed a high specific surface area of 421 m2/g. Monolithic barium hexa-aluminate formed. No BaO · Al2O3 or alumina was observed, as is often the case in powder processing. The specific surface area of the monolithic barium hexa-aluminate fired at 1400 °C for 2 h was 12 m2/g, while that of the barium hexa-aluminate xerogel was only 0.8 m2/g. A barium hexa-aluminate aerogel was also prepared using barium by using a chelating agent. This aerogel showed a specific surface area of 454 m2/g as-dried. In the case of the chelating agent, BaO · Al2O3 was also detected along with barium hexa-aluminate after firing.