September 14, 2017
Keio University
Kyoto University
Senior Assistant Professor Hironori Tsunoyama and Professor Atsushi Nakajima (principal investigator at the Keio Institute of Pure and Applied Sciences) of the Department of Chemistry, Faculty of Science and Technology, Keio University, in a joint research project with Associate Professor Yoshiyuki Mizuhata and Professor Norihiro Tokitoh (Director of the Institute) of the Institute for Chemical Research, Kyoto University, have developed a new method of directly implanting chemical species generated in the gas phase into a liquid. Using this method, they have successfully achieved the mass synthesis and structural determination of spherical "metal-encapsulating silicon nanoclusters M@Si16," which have a cage structure composed of 16 silicon atoms encapsulating a single metal atom.
Nanoclusters, which are aggregates of several to a thousand atoms or molecules, are larger than atoms and molecules but smaller than bulk materials, and they possess properties and functions different from both. Because their properties can be controlled by the number of atoms, composition, and charge state, they are expected to have applications in catalysts, electronic devices, and magnetic devices. Particularly in the field of electronics, a technology for creating ultrafine integrated structures with new functions by assembling individual nanoclusters of semiconductor materials like silicon, much like building blocks, is attracting attention. However, because the amount of nanoclusters synthesized in the gas phase has been extremely small, it has been extremely difficult to evaluate their structure from the perspective of material applications.
This research group mass-synthesized Ti@Si16 and Ta@Si16, which encapsulate titanium (Ti) and tantalum (Ta) metal atoms, respectively, in the gas phase and performed chemical purification by implanting them into a polyethylene glycol liquid. They also evaluated their structure, and the results revealed that these nanoclusters have a cage-like structure with a new bonding style not found in conventional silicon compounds. These findings are considered to be highly valuable as a fundamental technology for solar cells and electronic devices.
The results of this research were published in the online edition of "J. Phys. Chem. C," a journal of the American Chemical Society, on August 28, 2017 (US time).
Please see below for the full press release.