框架结构负热膨胀新化合物设计合成及机理

负热膨胀是一种反常的热学行为，它与声子、电荷和晶体结构之间的耦合作用息息相关。当前，负热膨胀的研究面临宽温区和强负热膨胀性难以兼得的问题。本项目从声子驱动型负热膨胀化合物入手，通过总结已知负热膨胀化合物及机理，设计合成框架结构由多原子桥连的碳化二亚胺类化合物，开拓框架结构负热膨胀化合物种类；结合电子与声子负热膨胀化合物机理特征，探索声子-电子双机制负热膨胀新机理；发展通过微观结构负热膨胀性能的化学调控方法，以期合成宽温区强负热膨胀化合物；借助大科学装置，基于同步辐射、中子衍射等技术，揭示化合物热膨胀机理，推动负热膨胀发展，建立构效关系。

Negative thermal expansion is a counterintuitive thermophysical behavior, which is correlated with the coupled interaction among phonon, charge and crystal structure. At present, it is difficult to obtain compounds with strong negative thermal expansion and wide working temperature range. This project starts with phonon-driven negative thermal expansion compounds. By summarizing the known negative thermal expansion compounds and their mechanisms, we designed and synthesized carbodiimide compounds with multi atom bridged framework structure, extend the variety of frame structure negative thermal expansion compounds; combining the characteristics of electron and phonon driven negative thermal expansion compounds, a new mechanism of phonon-electron double mechanism negative thermal expansion is explored; in order to synthesize strong negative thermal expansion compounds with wide temperature range, chemical control methods of microstructure negative thermal expansion were developed; based on synchrotron radiation, neutron diffraction and other techniques, the mechanism of thermal expansion of compounds was revealed. This project promotes the development of negative thermal expansion, and establishes structure-activity relationship.