oxycarbide

Oxycarbide is a term used to describe a class of materials that contain both oxide and carbide components within their chemical structure. In practice, this can refer to (1) amorphous or nanocrystalline networks in which silicon, boron, or other elements are bonded to both oxygen and carbon, or (2) multiphase or composite materials in which oxide-rich domains coexist with carbide-rich domains. The exact composition and bonding can vary widely, and the name reflects mixed anion chemistry rather than a single fixed compound.

Silicon oxycarbide (SiOC) is the most studied example. It is typically produced by pyrolyzing organosilicon polymers such as polycarbosilane or by sol-gel processing of siloxane precursors containing carbon. The resulting material is often a glassy or nanostructured ceramic with a network that includes Si–O–Si, Si–C, and Si–O–C bonds. SiOC can exhibit good thermal stability, relatively low density for a ceramic, and resistance to oxidation compared with some carbides. Its properties can be tuned by adjusting carbon content and heat treatment, influencing the balance between amorphous and nanocrystalline phases.

Transition-metal oxycarbides, including compounds based on tungsten, molybdenum, or other metals, are also studied. These materials can form under carburization or mixed oxidation and carburization conditions and are of interest as catalysts or catalyst supports, where the combination of oxide stability and carbide-like electronic structure may enhance activity for various reactions.

Synthesis methods include polymer-derived routes, chemical vapor deposition, and solid-state reactions, with microstructure ranging from amorphous to nanocrystalline. Applications span protective coatings, high-temperature components, wear-resistant materials, and catalytic systems.