New nanoparticle superstructures produced from pyramid-shaped bu…
Researchers from Brown College have assembled complicated macroscale superstructures from pyramid-shaped nanoparticle constructing blocks. The analysis, described within the journal Nature, demonstrates a promising new technique to carry the helpful properties of nanoparticles to macroscale supplies and units.
“There’s been a lot of research in making superstructures from spherical nanoparticles, but much less using tetrahedral building blocks,” stated Ou Chen, an assistant professor of chemistry at Brown and senior creator of the examine. “Tetrahedra open the possibility of making much more complex structures, and the 3D superstructure we demonstrate here is one of the most complex ever assembled from single nanoparticle components.”
Chen’s analysis group developed the constructing blocks used within the examine a 12 months in the past. The particles are quantum dots — nanoscale semiconductors that may take up and emit mild. Their tetrahedral (pyramid-like) form has essential benefits over spheres, Chen says, when utilizing them to construct bigger buildings. Tetrahedra can pack along with much less void area than spheres, making buildings probably extra strong. As well as, the particles used within the examine are anisotropic, which means they’ve totally different properties relying upon their orientation relative to one another. Spheres, alternatively, are the identical in each route.
Within the case of the tetrahedral quantum dots, anisotropy was generated by treating one flat face, or side, of every pyramid with a distinct ligand (a chemical bonding agent) than the opposite sides.
“Ligands help direct the touching process that occurs when two particles come together facet to facet,” stated Yasutaka Nagaoka, a postdoctoral researcher in Chen’s group and the main contributor to the venture. “In this case, facets with like ligands attract, which offers a degree of control over how the particles arrange themselves.”
That is in distinction to isotropic spheres, which prepare themselves randomly.
“Anisotropy adds to the complexity of the superstructures we can make compared to using isotropic spheres,” Chen stated. “It also gives us some power to control the atomic alignment of the particles in the supercrystals, which could give rise to interesting properties. For example, you can predict that alignment will give rise to better electronic properties because electrons hop more easily through the lattice of the superstructure.”
For his or her examine, Chen and his colleagues dissolved their tetrahedral quantum dots in resolution, then allowed the particles to assemble into three various kinds of superstructures: one-dimensional strands, two-dimensional crystal lattices and three-dimensional supercrystals.
The 3D supercrystals have been significantly attention-grabbing, Chen says, due to their complexity and the attention-grabbing manner wherein they fashioned. The person nanoparticles first fashioned ball-like clusters of 36 particles every. These clusters then fashioned the bigger superstructures. When the researchers characterised the construction intimately utilizing x-ray scattering, they discovered that the atomic construction of the lattice was certainly aligned, as they’d hoped.
Now that they’ve proven a way for forming the buildings, the subsequent step is to interrogate their properties.
“The quantum dot building blocks are interesting by themselves,” Chen stated. “They’ve attention-grabbing photon dynamics, which can translate into attention-grabbing optical properties within the superstructures.
“We need to understand how to assemble these larger and more complex structures,” he stated. “I think these will be a bridge that will bring nanoscale dynamics into the macroscale and enable new types of metamaterials and devices.”
Further co-authors on the paper have been Rui Tan, Ruipeng Li, Hua Zhu, Dennis Eggert, Yimin Wu, Yuzi Liu and Zhongwu Wang. The work was supported by the Brown College Salomon Analysis Fund, Brown’s Institute for Molecular and Nanoscale Innovation (IMNI) and the Nationwide Science Basis (DMR-1332208).
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