Getting ice by heating water
A group of Israeli scientists found a way to quickly turn supercooled water into ice. They used the fact that in an electric field, water changes its physical properties. Moreover, using the pyroelectric effect, it is possible to turn water into ice by heating it.
In general, the formation of ice usually occurs around some kind of litter or dust particles. If not, then in a perfectly clean atmosphere, even at ordinary pressure, water can retain a liquid form up to –42 ° C. This is the so-called supercooled water, which is used in medicine, cryogenics, etc.
The influence of the electric field on the freezing point of water has been known for more than 150 years: in particular, in a field of negative charge, water freezes at lower temperatures than in a field of positive charge. The most popular theory is that water molecules supposedly “change their orientation” in the field, which complicates the crystallization of ice. Oddly enough, this mechanism has not yet been fully studied. The problem is the lack of experimental data: scientists could not manage to find the material through which you can skip a charge and which does not react with water.
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An elegant experiment managed to come up with Igor Lubomirsky with colleagues from the Weizmann Institute (Israel). Scientists used pyroelectric lithium tantalate (LiTaO 3 ), which changes its electric field when heated / cooled. In the absence of a charge, water droplets on its surface freeze at –12.5 ° C. But if the surface is cooled, then lithium tantalate acquires a negative charge and water droplets remain liquid to –18 ° . If the surface is heated, in the field of positive charge, water freezes at –7 ° .
The results of scientific work published in the journal Science: David Ehre, Etay Lavert, Meir Lahav and Igor Lubomirsky, Science, 2010, DOI: 10.1126 / science.1178085. Buy an electronic version of the article here .
via Wired
In general, the formation of ice usually occurs around some kind of litter or dust particles. If not, then in a perfectly clean atmosphere, even at ordinary pressure, water can retain a liquid form up to –42 ° C. This is the so-called supercooled water, which is used in medicine, cryogenics, etc.
The influence of the electric field on the freezing point of water has been known for more than 150 years: in particular, in a field of negative charge, water freezes at lower temperatures than in a field of positive charge. The most popular theory is that water molecules supposedly “change their orientation” in the field, which complicates the crystallization of ice. Oddly enough, this mechanism has not yet been fully studied. The problem is the lack of experimental data: scientists could not manage to find the material through which you can skip a charge and which does not react with water.
')
An elegant experiment managed to come up with Igor Lubomirsky with colleagues from the Weizmann Institute (Israel). Scientists used pyroelectric lithium tantalate (LiTaO 3 ), which changes its electric field when heated / cooled. In the absence of a charge, water droplets on its surface freeze at –12.5 ° C. But if the surface is cooled, then lithium tantalate acquires a negative charge and water droplets remain liquid to –18 ° . If the surface is heated, in the field of positive charge, water freezes at –7 ° .
The results of scientific work published in the journal Science: David Ehre, Etay Lavert, Meir Lahav and Igor Lubomirsky, Science, 2010, DOI: 10.1126 / science.1178085. Buy an electronic version of the article here .
via Wired
Source: https://habr.com/ru/post/83468/
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