Led by Haimei Zheng, a scientist of the laboratory of Berkeley Division of materials Sciences, researchers used a combination of transmission electron microscopy and advanced technical handling liquid cell to carry out observations in real time of the growth of the NANORODS of nanoparticles of Platinum and iron. Their observations confirm the theory of nanoparticles act as artificial atoms in the crystal growth.
"We observed that nanoparticles become attached they formed initially winding polycrystalline chains," says Zheng. "These chains eventually align and join end-to-end of Nanowires of form of redress and stretch in NANORODS of single crystal with reports up to 40: 1 thick length.". This process of growth of nanocrystals, whereby NANOPARTICLE chains and nanoparticles serve the fundamental building blocks for NANORODS, is smart and efficient. »
Zheng is the author of a paper describing the research in the journal Science. The document is entitled "Imaging in real time of Pt3Fe solution nanorod growth." Co-authors are Liao Hong-Gang, Likun Cui and Stephen Whitelam.
If the infinite potential about nanotechnology is even be discussed, scientists must much better understanding of what size nano particles can assemble in hierarchical structures of the Organization and the increasing complexity. This agreement comes from monitoring of trajectories of growth of nano-particles and the forces that guiding these trajectories.
Through the use of the electron transmission and observation cells liquid, researchers at the laboratory at Berkeley and elsewhere have made significant progress by observing the nanoparticles of growth trajectories, including binding-oriented Nano - chemical phenomenon that starts the growth of nanocrystals in solution. However, these observations were generally limited to a few minutes from the crystal growth. In their study, Zheng and his colleagues were able to prolong the time of observation of the minutes to hours.
"" The key to the study of the growth of the colloidal nanocrystals with different forms and architectures is to maintain the fluid in the display window long enough to allow complete responses, "said Zheng." "" We dissolved molecular precursors of Platinum and iron in organic and used solvent capillary pressure to attract growth solution in liquid silicon nitride cell that we have sealed with epoxy. The seal of the cell was particularly important that he helped to maintain the viscous liquid Turning over time. Previously, we would often see liquids become viscous and would prevent the interactions of nanoparticles that promote crystal growth of place. »
Zheng and his colleagues chose to study the growth of the NANORODS of Platinum iron because of the promising potential of the material of the Electrocatalytic for use in the next generation energy conversion and storage devices. They could observe these nanoparticles to assemble Crystal nanorod with microscopes of powerful transmission of the laboratory of Berkeley National Center for electron microscopy, including the team 0.5 (Microscope) corrected by the Aberration of electronic Transmission, which can produce images with a resolution half-angstrom - less than the diameter of a single hydrogen atom.
"What we have found that only the nanoparticles exist at the beginning of the growth of the crystals, but, as the proceeds of growth, small strings of nanoparticles becomes dominant so far in, ultimately it may consider only long chains of nanoparticles," says Zheng. "Our observations provide a link between the world of simple molecules and hierarchical nanostructures, paving the way for the rational design of nanomaterials in controlled properties."
