Recent research on image crystals; Discovery of shape-controllable cavities surrounded by facets in ceramics

Serizawa, Hiroyuki  

My investigation on cavities in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO matrix. In a series of experiments, I noticed that the shape of the negative crystal changes depending on the heat-treatment history. In general, it is difficult to control arbitrarily the shapes of these polyhedral negative crystals embedded in a solid medium; however, the shape can easily be controlled using the helium injection method. Our research team named the shape controlled negative crystal as image crystal.