Tohoku University/Osaka University/Nagoya University, JAPAN
Our molecular-level optical in-situ observation for crystal growth from solutions were started in 1980. These were aimed to couple surface observation of crystals with the measurement of crystal growth rate, so as to verify proposed crystal growth mechanisms by direct experiments. At the initial stage of these works, we have used conventional interferometry and phase-sensitive microscopies like phase-contrast or differential interferometry, independently. These optical methods have been extended to real-time phase-shift (RPSI) to get molecular resolution, real-time. RPSI has been used to study growth of protein crystal, gypsum, calcite and some other crystal growth with extremely small solubility and thus growth/dissolution rates, the order of 10-5nm/s. This accurate measurement is also important for the understanding of natural water/rock interaction and the application to the nuclear waste management organization in Japan.
We wanted to observe the surface of growing crystals at atomic scale, for which optical methods are not suitable and thus we started to apply frequency modulated-AFM (FM-AFM) to the growth and dissolution of calcite, protein and some other minerals. FM-AFM is so sensitive that can measure the force between atoms at the crystal surface and the water molecules covering the crystals surface. In a sense, we could visualize the hydration structure that cover the real crystal surface in solution. This methodology would work to understand the effect of hydration on the growth rate, character of the surface and some other physical and chemical properties of crystal surfaces, if we couple MD simulations and X-ray surface diffraction. We have been approaching to a new step along the line where we analyze the type of each atoms on the crystal surface. This would be a bridge between physics and chemistry for materials science.
He started high resolution in-situ observation of crystal growth mainly from solution phases in 1983. The method were phase-sensitive microscopies and interferometry, both of which were later coupled to start real-time phase-shift interferometry with molecular resolution. Later he became interested in FM-AFM and other new methods for in-situ observation. His interest covers the areas of the fundamental studies of crystal growth mechanisms from liquids, the origin of solar materials that we say “crystallization 4.6 billion years ago”, protein crystal growth and perfection of semiconductor crystals, like GaN and SiC. He has also been interesting in in-situ experiments in microgravity for more than 20 years and have done many in-situ observations of crystal growth in space using rockets and international space station. Even now, many interferometric data on the growth mechanism of protein crystals have been arriving from International Space Station at our laboratories. He is the winner of Frank Prize in 2013 that was given by International Organization of Crystal Growth. After retiring from Tohoku University, he has been the invited professor of Osaka University and the guest professor of Nagoya University.
聯系人：刘 淼 副研究員（电话：82649407）