Prof. Shen Shengping’s team from Xi'an Jiaotong University, along with collaborators, has for the first time experimentally confirmed ice's flexoelectricity and a surface ferroelectric phase transition at approximately 160 K. Their study, titled "Flexoelectricity and Surface Ferroelectricity of Water Ice," was published in Nature Physics on August 27, 2025 (Beijing time), addressing the long-standing puzzle of ice electrification during collision or fracture—a key process in thundercloud lightning formation.

The team measured ice’s flexoelectric coefficient (around nC/m, comparable to that of SrTiO₃/TiO₂) and identified a critical phase transition at ~160 K via temperature-dependent tests. First-principles calculations further verified that Au/Pt electrodes stabilized the hydrogen order on ice surfaces, elevating the Ih-XI phase transition temperature to ~160 K and forming 15–35 nm ferroelectric surface layers. A thundercloud ice-graupel collision model showed the polarization charge matched wind tunnel data, suggesting flexoelectricity’s role in lightning generation.

Former Xi'an Jiaotong PhD Wen Xin is the first author, with Wen Xin, Prof. Shen Shengping, and Prof. Gustau Catalan as co-corresponding authors. The study was led by Xi'an Jiaotong University’s School of Aerospace Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures. Funding was provided by the National Natural Science Foundation of China.