Liu Bingbing, a research group at Jilin University, made important progress in the study of new carbon structure
Carbon materials are at the forefront of materials science. Carbon atoms have a variety of structures and properties of heterogeneous allotropes due to their rich bonding methods, which play an important role in the development and practical application of human science. Carbon material research not only promotes the development of materials science, but also promotes the progress of high voltage technology and nanotechnology. Exploring new carbon structures is a hot issue in the field of carbon materials research. In particular, the search for new sp3 structural carbon materials with performance comparable to or better than diamond has been a topic of great concern. The early progress in experiments was the superhard carbon structure formed in the post-graphite phase and cold-pressed carbon nanotubes found in cold-pressed graphite. Unfortunately, the diffraction signals of these two high-pressure phase structures are weak. The graphite phase could not be maintained at normal pressure, and the structure could not be determined. This led to a large number of theoretical studies, and many candidate structures were given. However, the structure has not been confirmed by experiments. It has been in dispute and experimentally synthesized new sp3. There has also been no major breakthrough in carbon materials.
Liu Bingbing's research group has long carried out research on high-pressure new structures and new properties of carbon materials such as fullerenes, and has achieved many innovation results, published in Science, PNAS, Adv Mater and other publications. In this work, unlike the graphite and carbon nanotube precursors containing only carbon six-membered rings used in previous experiments, the research team skillfully selected C70-limited carbon nanotube composites (C70peapod) containing carbon five-membered rings. As a precursor, an in-situ ultra-high pressure study was carried out to obtain a full sp3 superhard new carbon structure which can be intercepted at atmospheric pressure and completely different from diamond. Using direct experimental Raman spectroscopy, synchrotron radiation X-ray diffraction and other experimental techniques, combined with theoretical calculations, direct experimental evidence for the production of a new carbon phase was obtained. Synchrotron radiation XRD diffraction gives strong crystal diffraction information. The diffraction peak does not belong to any carbon structure reported in the past, but a new full sp3 carbon phase with a monoclinic structure (named Vcarbon) with slightly higher energy. In diamond, it has a hardness comparable to that of diamond, and gives a physical image of the conversion of C70 peapod material to V carbon. It is found that the odd carbon rings contained in the initial material play an important role in the formation of V carbon. The research results will inspire people to design and use new precursors combined with high-pressure technology to build new carbon materials with excellent performance, which provides a new idea for the development of new multifunctional materials.
The first author of the paper is Yang Xigui, a Ph.D. student at Jilin University. Wu Xiangying, a master student, is responsible for theoretical calculations. Professor Liu Bingbing and Professor Yao Mingguang from Jilin University are co-authors. The research work was funded by the National Natural Science Foundation of China, the Education Minister Jiang Scholars and the Innovation Team Development Program and the Jilin University Graduate Innovation Research Program.
Article link: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.245701
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