Intuition suggests that a sample of material compressed uniformly from all sides should reduce its dimensions. Only a few materials subjected to hydrostatic compression exhibit the opposite behaviour, expanding slightly in one or two directions. Researchers at the Institute of Physical Chemistry of the Polish Academy of Sciences have developed a material with exceptionally high negative compressibility via a previously unknown mechanism.
When you squeeze something, you usually expect it to shrink, particularly when the pressure exerted acts uniformly from all sides. However, there are materials which, when subjected to hydrostatic pressure, elongate slightly in one or two directions. During the search for optimal compounds for hydrogen storage, researchers made an accidental, albeit very interesting, discovery: Under increasing pressure, one of the tested materials elongated significantly.
"Usually, the increase in dimensions observed in materials with negative compressibility subjected to high hydrostatic pressure is small. We are talking here about values of the order of a single percentage point or even less. We have found a material of very high negative compressibility, of up to 10% in one direction. Interestingly, the elongation occurred abruptly at a pressure of approx. 30 thousand atmospheres," says Dr. Taras Palasyuk (IPC PAS).
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