Direct Conversion of Carbon into Diamond and Useful Micro and Nanostructures

North Carolina State University, Raleigh NC

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: This project focuses on direct conversion of carbon into diamond at ambient temperatures and atmospheric pressures in air. By NCSU's transformative approach, carbon can be converted into so-called Q-carbon (named because of laser quenching) and diamond in a variety of useful nanostructures and microstructures in the form of nanoscale needles, microscale needles, nanoscale dots, microscale crystals, and large-area single-crystal films on practical substrates such as sapphire, glass and heat-sensitive polymers. These microscale and nanoscale structures have potential applications, e.g., as cutting tools and high-speed machining; and in high-power, quantum computing devices, and biomedical devices. The goals in this very critical stage are to develop a basic understanding and address issues related to scale-up and manufacturing of diamond-related products. This project has a strong education value through training of graduate students in this exciting new area in collaboration with NC A&T faculty and students. TECHNICAL DETAILS: This research addresses fundamental understanding and investigations of basic mechanisms involved in the direct conversion of carbon into diamond. By using nanosecond pulsed laser irradiation, carbon is melted in a highly undercooled state at 4000 K (over 1000 K below the melting point of carbon). This state is then quenched to form Q-carbon (a new phase of carbon) or diamond or a mixture of both; the result depends on the degree of undercooling. Q-carbon has many exciting new properties, including ferromagnetism, super hardness and enhanced field emission for next-generation displays. Q-carbon is converted into diamond by laser irradiation with a second laser pulse. By controlling interfacial instability during rapid quenching nanodots, microdots, nanoneedles and microneedles are created with a single nanosecond laser pulse; the entire process is completed in less than two hundred nanoseconds. This novel approach provides an inexpensive way to convert carbon into diamond and harvest various structures conveniently for a variety of applications. This research expands our fundamental knowledge base on laser-solid interactions and transient thermal processing of materials, and on the critical role of structure, defects and chemistry in the properties of novel Q-carbon and diamond-based structures.