Recently, the National Research Center for Materials Science of the Institute of Metals of the Chinese Academy of Sciences in Shenyang has made a major scientific research progress and successfully developed an innovative covalently bonded diamond graphite material. This material combines the ultimate hardness of diamond with the excellent toughness and conductivity of graphite, indicating its broad application prospects in the fields of superhard materials and electronic device technology. This achievement is attributed to the significant breakthrough of the research team in the technology of Ionic Chemical Vapor Deposition (CVD). They not only successfully prepared this new material, but also deeply explored its growth mechanism and electronic properties.
For a long time, diamond and graphite, as different forms of carbon elements, have attracted attention due to their unique physical and chemical properties. However, the covalent interface generation energy between the two is extremely high, and the traditional synthesis path relies on extreme high temperature and high pressure environments, which not only complicates the process but also hinders further optimization of material properties.
The team led by researcher Huang Nan has achieved innovation within the existing plasma CVD technology framework. By cleverly designing a confined ceramic base, the electron density in the plasma has been significantly increased to 2.7 times the original level, providing necessary energy support for the activation of carbon atoms and their covalent linkage with diamond and graphite. Through transmission electron microscopy observation, it was found that a unique and precisely matched covalent connection was formed between specific crystal planes of diamond and graphite, which is significantly different from similar interfaces prepared by traditional high-temperature and high-pressure methods.
A deeper level of electron energy loss spectroscopy analysis reveals an increase in electron density in the graphite region at the interface, demonstrating the unique properties of sp2/sp3 hybrid carbon and proving the strong interaction between diamond and graphite constructed through covalent bonding. The team utilized first principles calculations to elucidate how this interface interaction regulates electron transfer and distribution, affecting the electronic properties of interface carbon atoms, leading to an abnormal increase in the density of states of graphite near the Fermi level, and the formation of local energy levels at the bottom of the diamond conduction band.
This study not only reveals the growth mechanism of covalent diamond graphite materials, but also demonstrates how to modulate the electronic properties of materials by precisely controlling the preparation process. The research results are titled "Collegantly bonded diamond nanoplates with engineered electronic properties of diamond" and have been published in the internationally renowned academic journal "Advanced Functional Materials". They have also received funding from institutions such as the National Natural Science Foundation of China.
This study not only elucidates the growth principle of covalent diamond graphite materials, but also demonstrates a new approach to customize the electronic properties of materials through finely tuned preparation processes. The related research results, titled "Covalent Dicarbide Nanosheets with Engineering Electronic Properties," were published in the international authoritative academic journal "Advanced Functional Materials," and received funding from various sources including the National Natural Science Foundation of China, marking an important milestone in the field of carbon based materials science.
