Real-Time Visualization of Nanocrystal Solid–Solid Transformation Pathways

• Published in: Nano letters 2014-04, Vol.14 (4), p.1995-1999
• Main Authors: Wittenberg, Joshua S, Miller, Timothy A, Szilagyi, Erzsi, Lutker, Katie, Quirin, Florian, Lu, Wei, Lemke, Henrik, Zhu, Diling, Chollet, Matthieu, Robinson, Joseph, Wen, Haidan, Sokolowski-Tinten, Klaus, Alivisatos, A. Paul, Lindenberg, Aaron M
• Format: Article
• Language: English
• Subjects: Cadmium; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Dynamics; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Materials science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Pathways; Phase transformations; Physics; Specific phase transitions; Stresses; Structural transitions in nanoscale materials; Sulfides; Transformations; X-rays
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl500043c

Measurement and understanding of the microscopic pathways materials follow as they transform is crucial for the design and synthesis of new metastable phases of matter. Here we employ femtosecond single-shot X-ray diffraction techniques to measure the pathways underlying solid–solid phase transitions in cadmium sulfide nanorods, a model system for a general class of martensitic transformations. Using picosecond rise-time laser-generated shocks to trigger the transformation, we directly observe the transition state dynamics associated with the wurtzite-to-rocksalt structural phase transformation in cadmium sulfide with atomic-scale resolution. A stress-dependent transition path is observed. At high peak stresses, the majority of the sample is converted directly into the rocksalt phase with no evidence of an intermediate prior to rocksalt formation. At lower peak stresses, a transient five-coordinated intermediate structure is observed consistent with previous first principles modeling.