Scale and rate dependence of phase transition pressure in CdS nanoparticles

Recent efforts to improve our predictive capability for modeling rate-dependent behavior at, or near, phase transition using molecular dynamics simulations will be described. Cadmium sulfide is a well-studied material which undergoes a solid-solid phase transition from wurtzite to rock salt structures between 3 and 9 GPa. Atomistic simulations are used to investigate the dominant transition mechanisms as a function of orientation, size and rate. The CdS solid-solid phase transition is studied, for both a bulk single crystal and for polymer-encapsulated spherical nanoparticles of various sizes. The transition kinetics, mapped to nanoparticle size and loading rate, will be discussed for particles of diameter 2 to 10 nm. Finally, we will briefly review the experimental effort to investigate this transition using X-ray diffraction on the Thor platform at Sandia. Supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.