“弘扬科学家精神 激发全社会创新活力”科技活动周系列报告

题目：Unlocking High Pressure Materials Science Through Single-Crystal X-ray Diffraction: Novel Binary and Ternary C-N Solids

报告时间：2024年5月23日（周四）上午09:30

报告地点：超硬实验综合楼5楼B520报告厅

报告人：Dr. Dominique Laniel，英国爱丁堡大学

个人简介:

Dominique Laniel's is a Canadian-born physicist currently working at the Centre for Science at Extreme Conditions (CSEC) of the University of Edinburgh, United Kingdom. He was appointed lecturer in 2022 after obtaining a prestigious Future Leaders Fellowship, which allowed him to establish his research group and set up his laboratory. Dominique did his PhD in Paris, France, under the direction of Paul Loubeyre, followed by a postdoctoral appointment at the University of Bayreuth, Germany, working with Leonid Dubrovinsky.

His research projects mainly focus on the investigation of simple molecular systems such as N₂ and O₂ as well as the synthesis of novel functional materials under extreme pressure-temperature conditions (up to ~2,000,000 bars and ~5,000 K) employing laser-heated diamond anvil cells. In particular, he focuses on producing novel single-bonded nitrogen-based high energy density materials with applications as environmentally-friendly high-performance rocket fuel and explosives, superhard materials for ultra-resistant coatings and smart resilient machining tools as well as new anodes for next-generation battery materials.

报告摘要：

The thermodynamic parameter pressure is an immensely powerful tool to tune the Gibbs free energy landscape, in turn enabling the formation of novel materials inaccessible at ambient conditions. As it stands, this approach is largely underexploited, with only about 3% of all known materials having been produced at a pressure different from one atmosphere.

In this talk, it will be demonstrated that pressure can be used to form long-sought after C₃N₄ carbon nitrides composed of corner-sharing CN₄ tetrahedra. These materials, initially proposed to have a hardness comparable or even harder than diamond, will be shown to be synthesizable from several C-N precursors in laser-heated diamond anvil cells. Their mechanical properties and stability range will be discussed. Moreover, an investigation of the ternary C-N-H system will be presented, of relevance for both planetary interiors but also as a mean to produce high-resilience CN₄-based frameworks at much lower pressures than in the binary C-N system. The ubiquity of CN₄ tetrahedra at high pressures will also be demonstrated, namely in the context of ternary rare-earth C-N systems. Throughout the talk, the importance of having a reliable and DFT-independent structure determination approach—i.e. single-crystal X-ray diffraction of polycrystalline samples—will be emphasized and the method described.