Many of the materials around us are polycrystalline materials composed of many crystals or "grains". Grain boundaries are interfaces between two grains of different orientations, and their structures and properties depend on the crystal orientation relationship between the neighbouring grains. The properties of grain boundaries often control the physical properties of the entire polycrystalline material. One example of the importance of grain boundaries is the issue, recently in the news, of cracks in nuclear reactors. In many cases the cause is the the "stress corrosion cracking" phenomenon, which occurs preferentially along grain boundaries. Thus a phenomenon that occurs locally on a nanometre scale governs the performance and reliability of the entire structure. However, an important point is that all types of grain boundaries necessarily have the same effect and there are certain types at which stress corrosion cracking hardly occurs at all.

　Similarly, in polycrystalline silicon solar cells, a key technology in the search for greener and cleaner energy, grain boundaries are one of the main causes of losses causing decreases in the conversion efficiency of sunlight to electrical energy, but it has been shown that not all grain boundaries contribute to this loss to the same extent. These two examples show that it is important to make the best use of the individual characteristics of grain boundaries to design and control materials properties. The research in our group takes as its basis grain boundary and interface science and engineering and the PMP triangle of 'Microstructure-Properties-Processing', with the aim of developing advanced materials with excellent function and performance.