Detecting material transmitting electricity but not transmitting heat, contrary to the law in textbooks

Vanadium dioxide (VO2), which is the name of a special, conductive metal that does not transfer heat, was announced by scientists. VO2 with its special features can lead wires to a new history.

VO2 was first discovered in 2017. At that time, scientists were extremely surprised by its features that went against Wiedemann-Franz's Law - good conductors will conduct heat well, cause causing electrical appliances to be operated continuously to heat up.

Tests for VO2 show that the metal transmits electricity without transmitting heat. In its natural state, VO2 is inherently strange. At temperatures below 32 degrees Celsius, a block of VO2 glass will be transparent but when at temperatures above 60 degrees Celsius, it will darken, turn into a kind of light shield and let electricity flow through.

Junqiao Wu, head of research at Berkeley Lab, said the discovery of VO2 is of great importance, allowing us to understand the nature of exotic conductive materials.

Previously, researchers have also found some substances that can conduct electricity better than conduct heat, but only if the material is in a hundred-degree negative environment. Particularly with VO2, it can transmit electricity only at warm temperatures, so its practical applicability is immense.

Looking at how electrons move inside the VO2 crystal lattice, the researchers found that the heat transfer generated inside VO2 when the electrons moved was 10 times smaller than the amount that Wiedemann-Franz's Law pointed out. out. This shows that the electrons in VO2 have moved in a way that is different from how they behave in the single particle form of electrons in the common metal we often see.

According to Professor Wu, the electrons in VO2 move in a uniform way which is no different from fluid flow so there is not much heat generated.

In particular, when mixing VO2 with other materials, the researchers can adjust the amount of electricity and the amount of heat moving inside the material. For example, when tungsten is mixed into VO2, the newly created compound is able to conduct heat more efficiently. This means that VO2 has the ability to dissipate heat when heated to a certain temperature, while it has not yet reached that temperature it is an insulator.

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