Nanocrystals with metastable high-pressure phases under ambient conditions
Tianyuan Xiao, Yasutaka Nagaoka, Xirui Wang, Tian Jiang, Derek LaMontagne, Qiang Zhang, Can Cao, Xizheng Diao, Jiahua Qiu, Yiruo Lu, Zhongwu Wang, Y. Charles Cao
Abstract
The ambient metastability of the rock-salt phase in well-defined model systems comprising nanospheres or nanorods of cadmium selenide, cadmium sulfide, or both was investigated as a function of composition, initial crystal phase, particle structure, shape, surface functionalization, and ordering level of their assemblies. Our experiments show that these nanocrystal systems exhibit ligand-tailorable reversibility in the rock salt-to-zinc blende solid-phase transformation. Interparticle sintering was used to engineer kinetic barriers in the phase transformation to produce ambient-pressure metastable rock-salt structures in a controllable manner. Interconnected nanocrystal networks were identified as an essential structure that hosted metastable high-energy phases at ambient conditions. These findings suggest general rules for transformation-barrier engineering that are useful in the rational design of next-generation materials.