The Strongest Particle: Size-Dependent Elastic Strength and Debye Temperature of PbS Nanocrystals.
We investigated the elastic compressibility of PbS nanocrystals (NCs) pressurized in a diamond anvil cell and simultaneously probed the structure using synchrotron-based X-ray diffraction. The compressibility of PbS NCs exhibits bimodal size dependence. The elastic modulus of small NCs increases with increasing diameter and peaks near a particle diameter of approximately 7 nm. For large NCs the elastic modulus decreases toward the bulk value with increasing NC diameter. We explain the bimodal size-dependence of the elastic modulus in terms of a core-shell model based on distinct elasticity of the crystal near the surface and in the core of the particle. We combined insights into the size-dependent elasticity and lattice spacing to determine the Debye temperature of PbS NCs as a function of particle diameter. Understanding the size-dependent elasticity of defect-free colloidal NCs provides new insights into their crystal structure and mechanical properties.
†School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States.
Kaifu
K
Bian
†School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States.
William
W
Bassett
†School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States.
Zhongwu
Z
Wang
†School of Chemical and Biomolecular Engineering, ‡Department of Earth and Atmospheric Sciences, and §Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853, United States.
Tobias
T
Hanrath
Debye temperature; X-ray diffraction; colloidal nanocrystals; mechanical properties