Hybrid material Gradia-HZ exhibits tunable semiconducting and metallic properties

Understanding the properties of carbon-based materials, particularly graphite-diamond hybrid materials known as Gradia, holds promise in materials science. Questions remain in deciphering the diverse architecture types and variable proportions of these hybrid structures, which directly influence their properties and potential applications.

Gradia-HZ is a specific type of Gradia, constituted by interfaced graphite and hexagonal diamond. Ge et al. mathematically explored its physical properties like elastic constants, electronic structures, and electronic transport properties, with varied graphite-diamond proportions in the unit cell. Their findings demonstrate the versatility of Gradia-HZ, which can transition from a topological nodal-line semimetal to a semiconductor and normal metal as the width of graphite within the unit cell ismodified.

“Emerging as a distinct and substantial breakthrough in the field of carbon-based materials, the graphite-diamond hybrid material has recently been confirmed through experimentation,” said Yanfeng Ge. “Here, the study of the new hybrid structure composed of hexagonal diamond and graphite in our work is very timely and interesting.”

The group found that Gradia-HZ could possess a Vickers hardness exceeding 40 GPa, indicative of superhard material properties. Additionally, electronic transport properties computations revealed excellent carrier mobility comparable to silicon for Gradia-HZ semiconductors and extreme resistivity even lower than gold, silver, or copper for Gradia-HZ metals.

The work demonstrates that combining different allotropes lead to fascinating new hybrid structures with unique properties, which will have thought-provoking implications for exploring new materials.

Ge hopes to investigate experimental preparation techniques that can produce Gradia with specific structures, such as the controllable synthesis of Gradia from multilayer graphene sheets under high pressure and appropriate temperature.

Source: “Graphite-hexagonal diamond hybrid with diverse properties,” by Yanfeng Ge, Kun Luo, Yong Liu, Guochun Yang, Pan Ying, Yingju Wu, Ke Tong, Bing Liu, Baozhong Li, Guoying Gao, Xiang-Feng Zhou, Zhisheng Zhao, Bo Xu, and Yongjun Tian, Applied Physics Reviews (2023). The article can be accessed at https://doi.org/10.1063/5.0151183 .