EAGER: Exploring Routes to Nanocomposites Linking Silicate and Carbon-Based Structures

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NONTECHNICAL DESCRIPTION: Modern technology demands strong lightweight materials with properties tailored to specific applications. Nanostructured materials containing silicon, carbon, oxygen, and nitrogen are of interest in applications ranging from lithium ion battery electrodes to spark plugs to high temperature materials in the aerospace industry. Heretofore their synthesis has been by laborious and expensive pathways involving toxic organosiliicon polymer precursors and giving this class of materials the name polymer-derived ceramics (PDC). This project explores alternate synthesis routes to these and related materials. Materials with new structures may be discovered, and understanding will be gained about their properties, stability and possible new applications. This research may pave the way to more economical and environmentally benign manufacturing methods. Furthermore it is possible that related materials may exist in planetary interiors at high pressure, and this project thus may impact geology and planetary science as well as materials science. TECHNICAL DETAILS: Strong, lightweight and unreactive ceramic materials for use at high temperature are needed for applications in aerospace, automotive, nuclear, and other industries. Though direct reaction of silica with carbon, silicon carbide and/or silicon nitride to form multicomponent amorphous, glassy, or crystalline materials has met with little success, a polymer precursor route, has led to a new class of very interesting materials called polymer-derived ceramics (PDC). Their recently discovered thermodynamic stability suggests that they and/or related materials should be accessible by other, perhaps simpler, pathways. This project explores such alternative syntheses, using various reactive and nanophase starting materials. The goal is to generate new materials avoiding expensive, difficult, toxic, and dangerous organosilicon polymer precursors. Starting materials involving organic molecules confined in mesoporous silica and metal organic frameworks will be explored, with pyrolysis under atmospheric pressure, laser ablation, and high pressure reactions as possible synthetic pathways. Furthermore it is possible that related materials may exist in planetary interiors at high pressure, and this project thus may impact geology and planetary science as well as materials science. This project will train young scientists in synthetic and characterization techniques and in relating concepts in synthesis, structure, physical properties, and thermodynamic stability.