A research group made up of Associate Professor Akira Miura and Professor Kiyoharu Tadanaga of the Graduate School of Engineering, Graduate Student Kotaro Maki of the Graduate School of Chemical Sciences and Engineering at Hokkaido University (at the time of the research), Assistant Professor Koki Muraoka of the University of Tokyo, Assistant Professor Kazuhiro Hikima of Toyohashi University of Technology, Associate Professor Yoshikazu Mizuguchi of Tokyo Metropolitan University, Professor Chikako Moriyoshi of Hiroshima University, Associate Professor Hiroshi Nakajima of Osaka Metropolitan University, Researcher Hiroshi Oike of the Japan Science and Technology Agency, and Assistant Professor Wenhao Sun of the University of Michigan observed martensitic transformation and resulting unique softness in the ternary sodium chloride Na3YCl6. The results were published in the Journal of the American Chemical Society.
Provided by Hokkaido University
Chlorides, such as sodium chloride (NaCl), are ionic crystals that generally show brittle mechanical properties. Since mechanical properties depend on the bonding in crystal structures, it has been considered difficult to significantly change mechanical properties.
In this study, the research group observed that in Na3YCl6, a chloride with both monoclinic and rhombohedral structures, martensitic transformation from a monoclinic to rhombohedral structure occurs accompanied by large volume expansion due to stress. They proposed that the transformation of the crystalline phase causes the material to develop unique softness.
Martensitic transformation is a type of phase transition in which one crystalline phase changes to another and is known to improve the mechanical properties of steel-based materials and partially stabilize zirconia. The martensitic transformation and unique mechanical properties observed in this study are similar to the phase transformation and mechanical-property changes of partially stabilized zirconia, which were observed about half a century ago and are currently leveraged in practical applications. This provides a new concept for improving the mechanical properties of non-oxide materials that have not received much attention till now.
Journal Information
Publication: Journal of the American Chemical Society
Title: Stress-Induced Martensitic Transformation in Na3YCl6
DOI: 10.1021/jacs.4c09476
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