“…4) 6) Perhydropolysilazane (PHPS) has been extensively studied as a carbon free polymer precursor, that is readily oxidized to yield pure silica with a high ceramic yield, either by pyrolysis in air, 7) or by exposure to aqueous ammonia vapour at room temperature. 8), 9) To date, micro-and meso-porous structures formation has been often discussed for the polymer-derived amorphous ceramics such as silicon nitride (Si N), 10), 11) silicon carbide (Si C), 12) 17) silicon carbonitride (Si C N), 18) quaternary Si M C N (M=B, 19), 20) Ni 21) ), silicon oxycarbide (SiOC), 22) 24) and silica (Si O). 7),25), 26) During the crosslinking and subsequent hightemperature pyrolysis of polymer precursors, by-product gases such as CH 4 , NH 3 and H 2 were detected, 5), 27) and the microporosity in the polymer-derived non-oxide amorphous ceramics could be assigned to the release of the small gaseous species formed in-situ.…”