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Pavel Kotov
A group of scientists from Michigan State University reported regarding getting a liquid that “defies simple theoretical explanations”because it exhibits piezoelectric properties. The material can be used in optical devices or in “new field of piezohydraulics”.
Image source: pubs.acs.org
The piezoelectric effect, that is, the polarization of a dielectric during mechanical deformation, was discovered in 1880. There is also the opposite effect – the occurrence of mechanical deformations in an electric field. Materials possessing such properties – piezoelectrics – are now used very widely. They are used in quartz watches, amplifiers, transformers and even lighters. But until now, they have been solids, because piezoelectric fluids have not been observed.
A new property of the substance was discovered during the study of two ionic liquid salts: when they were placed in a cylinder and began to be compressed by a piston, both liquids began to generate electricity in proportion to the applied force, and this, as the head of the research group, Professor Gary Blanchard, put it, “shocked us to hell”. In addition, the effect was found in the liquid “induced free charge gradient”corresponding to the inverse piezoelectric effect.
Until now, it was believed that only materials with a crystalline structure, which are highly ordered, can be piezoelectrics. Therefore, scientists did not even try to detect such properties in liquids. Now researchers are trying to study the mechanisms of the occurrence of the piezoelectric effect in liquids, as well as to find new substances from this group with higher conductivity, because the piezoelectric effect identified in these liquids manifests itself “an order of magnitude smaller than quartz».
The authors of the study have already tried to put their discovery into practice by placing liquids in a lens-shaped container – by acting on it with electricity, they were able to change the focal length. They also noted that the discovery would require changes in the theory of the piezoelectric effect to explain the experimental observations. Finally, these fluids promise to be environmentally friendly in industrial applications—unlike many solid piezoelectrics, they do not contain lead.
