X-ray diffraction reveals the freeze-thaw cycle of krypton trapped in the cylindrical pores of mesoporous silicon and the hexagonal pores of mesoporous carbon. The melting point is significantly depressed in both materials, according to research by Kunimitsu Morishige, Okayama University of Science, Japan. The freezing and melting points are the same in carbon but very different in silicon; a pronounced hysteresis effect.

Understanding this hysteresis effect and why it apparently occurs in some porous materials and not others is fundamental to condensed matter science, but could also have implications for handling materials in lab-on-a-chip devices.

• Freezing and Melting of Kr in Hexagonally Shaped Pores of Turbostratic Carbon: Lack of Hysteresis between Freezing and Melting
  K. Morishige,
  J. Phys. Chem. C 2011.
  DOI: 10.1021/jp108036q