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.