Morphology Tuned Wurtzite-Type ZnS Nanobelts

Los Alamos National Laboratory's Zhongwu Wang and colleagues recently reported new insights into the behavior of wurtzite-type ZnS with respect to structural stability, phase transformation and fracture in the November 13th advanced published paper at the journal Nature Materials. Wurtzite-type ZnS nanobelts have a {210}-dominated surface morphology, which has the lowest surface energy. Such a particular low-energy surface structure greatly expands the structural stability of wurtzite to 6.8 GPa from an unstable phase at ambient conditions, and further results in an in-situ fracture upon the explosive transformation from wurtzite to sphalerite.

The group combined in-situ synchrotron x-ray diffraction and TEM characterization, and observed the broken particle size to be ~10nm. This particle size is coincidentally equal to the critical size observed in materials that have the theoretical yield strength below this size. This study allows us to better understand the morphology-tuned mechanisms that differ from those exist in bulk and three-dimensional nanoparticle counterparts. The result provides information important for designing the optimum path for synthesis of the multi-functional nanoforms with enhanced optical and electronic properties for technological application.

The recent proposal for the role of nanoparticles in earthquakes mechanisms and the strong mechanical properties of nano-building blocks with mixture of brittle nanobelts and soft protein in several kinds of biocomposites, such as bone and nacre, the observed mechanisms in this study could also enable to understand the microscopic mechanism of nature and further to synthesize the functional nanocomposites with excellent mechanical properties. [Wang, Z. W. et al., Nature Materials, doi:10.1038/nmat1522, Advanced online publication (2005)].