Nitridation and densification of SiO2 aerogels

Nitridation of SiO2–B2O3 aerogels

“…The amount of nitrogen always exceeds 20 wt%. This is a higher value compared with the amount of nitrogen incorporated into a pure silica aerogel nitrided at the same conditions (6 h, 1200°C) [2]. It should be noticed that the maximum content of nitrogen in SiO 2 -B 2 O 3 aerogels was 28.4 wt%.…”

“…In almost all the samples the specific surface area decreases less than 100 m 2 /g retaining most of their original surface area. This is a much smaller value compared with silica aerogel where the shrinkage and change of specific surface are 42% and 200 m 2 /g, respectively [2].…”

“…Fig. 2 shows a comparison of the FTIR spectra obtained for SiO 2 [2] and SiO 2 -B 2 O 3 aerogels. Silica aerogel exhibits typical bands for Si-O-Si vibration at 1088, 800 and 460 cm À1 .…”

“…We have found that more than 20 wt% of nitrogen can be incorporated in silica aerogels during long time (>10 h) heat treatment in ammonia (ammonolysis) at 1200°C. In addition to that, some of the nitrided aerogels have been densified to monolithic oxynitride glasses containing 8.4-13 wt% of nitrogen [2]. In this work, we present the results of nitridation of SiO 2 -B 2 O 3 aerogels.…”

Preparation of nanostructured porous SiO2-Al2O3 oxycarbonitride materials obtained by a new chemical precursor method

“…Isocyanate-modified siloxanes are a new class of precursors containing Si-N and Si-C bonds, which are often used to obtain optical glasses by the solgel method, and remain stable during the synthesis process [1]. To the best of our knowledge there is not any bibliographic data for the use of isocyanatecontaining alkoxides as precursors for the oxycarbide and carbonitride porous hybrid materials synthesis.…”