A research group led by Professor Yuichi Ikuhara at WPI Advanced Institute for Materials Research, Tohoku University (concurrently serving as Professor at School of Engineering, University of Tokyo and Senior Researcher at Japan Fine Ceramic Center (JFCC)), and Assistant Professor Zhongchang Wang at WPI Advanced Institute for Materials Research, Tohoku University has discovered that very small amount of impurities on grain boundaries of ceramics (magnesium oxide) form an unexpected superstructure at the atomic level, through the observation with an atom-resolved aberration-corrected scanning transmission electron microscope and the supercomputing calculation. That is, they have revealed that impurities inside of a ceramic crystal accumulate at grain boundaries and form ordered three-dimensional structure (superstructure). Since even a very small amount (at ppm-level) of impurities may change characteristics of ceramics and enhance fluctuation of product properties, it had been difficult to extend the commercial uses of ceramics. This study has found that an origin resulting in fluctuation of the properties is significant transformation of atomic structures by segregation of ultra-diluted impurities at/near grain boundaries. In other words, this research has visualized the position of impurities which is too small amount to detect, and has elucidated the role of impurities for changing the properties. This study will be expected to greatly improve performance and reliability of ceramics by controlling impurities to significantly contribute to inhibit fluctuations of the properties, and develop unprecedented materials which superstructures are controlled by applying intentionally impurities.

 This research result will be published online in Nature on November 16, 2011. The paper’s title is “Atom-resolved imaging of ordered defect superstructures at individual grain boundaries”. This research has been conducted with the aid of Grant-in-Aid for Scientific Research on Priority Areas, ”Atomic Scale Modification (474)”, from Japan Society for the Promotion of Science.

More information (Japanese)

[Contact]

Professor Yuichi Ikuhara

Institute of Engineering Innovation,

School of Engineering, University of Tokyo

Address: 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan

TEL: +81-3-5841-7688

E-mail：ikuhara*sigma.t.u-tokyo.ac.jp (Replace * with @)

Assistant Professor Zhongchang Wang

WPI Advanced Institute for Materials Research, Tohoku University

Address: 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan

TEL: +81-22-217-5934

E-mail：zcwang*wpi-aimr.tohoku.ac.jp (Replace * with @)