In situ formation of tungsten oxycarbide, tungsten carbide and tungsten nitride nanoparticles in micro- and mesoporous polymer-derived ceramics

Abstract

We present a facile approach to design micro- and mesoporous ceramic nanocomposites, which avoids the sintering of nanoparticles even at high synthesis temperatures and in situ forms nanoparticles in high temperature stable porous silicon oxycarbonitride (SiOC(N)) matrices. Our case study includes the synthesis of micro- and mesoporous polymer nanocomposites (c-WO_3−x/WO₃×H₂O/[–Si(O)CH₂–]_n) which contain cubic tungsten oxide and tungsten oxide monohydrate (c-WO_3−x/WO₃×H₂O) nanowhiskers in highly micro- and mesoporous polycarbosilane–siloxane matrices. The thermolysis of c-WO_3−x/WO₃×H₂O/[–Si(O)CH₂–]_n nanocomposites under a suitable atmosphere and temperature leads to the in situ formation of well-dispersed nanoparticles of cubic tungsten oxide (c-WO_3−x), tungsten oxycarbide (W₂CO), tungsten carbide (WC) and tungsten nitride (WN) in micro- and mesoporous matrices.