This research group, which has been trying to analyze the atomic structure and elucidate the mechanism of expression of functional characteristics for lattice defects, grain boundaries, interfaces, etc. in crystals, has made full use of the most advanced atomic resolution scanning transmission electron microscopy. Then, the grain boundaries of various oxides and the atomic structure near the interface were observed in detail.As a result, a unique atomic arrangement with randomness was discovered by analysis of the magnesium oxide thin film layer.

　This extremely peculiar structure, in which there are atomic columns (columns) with a one-dimensional periodic structure in one direction and they are distributed two-dimensionally randomly (disordered), is called a "one-dimensional ordered crystal". It was named.The atomic structure of a one-dimensional ordered crystal, which can be said to coexist with one-dimensional periodicity and two-dimensional randomness, has not been reported so far and is completely different from the structure of known oxides. It is thought that the structure appears in a region with a certain volume surrounded by bulk crystals, such as the triple point of grain boundaries where two grain boundaries meet and the vicinity of the crystal interface.The research group has already confirmed that this structure exists not only in magnesium oxide but also in the vicinity of the interface of other ceramic materials such as neodium oxide, and it should be a structure that can exist in a bound space with a certain volume. Became clear.

　One-dimensional ordered crystals have the potential to develop new functions that have never been seen before, and it is expected that this discovery will lead to the development of new one-dimensional ordered crystalline materials with unique functional characteristics. ing.

Paper information:[Nature Materials] Ceramic phases with one-dimensional long-range order