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Bizarre Metal Conducts Electricity but not Heat


Every once in a while, scientists come across new materials that seem to define the laws of physics. Exotic properties aren’t anything unprecedented, but having a metal that can conduct electricity but not heat raises many questions about its internal molecular structure and composition. In fact, there’s a physics law named “Wiedemann-Franz Law” which states that electrical conductors are also heat conductors. As it seems, this law has at least one exception, and researchers at the Berkeley Lab of Material Sciences have found it.

The metal is vanadium dioxide (VO2) which has already sparked the interest of the scientific community in the recent past. It is the same material that was found to be able to switch from a see-through insulator to a conductive metal in low temperatures, as proven by researchers from the RIKEN Center for Emergent Matter Science back in 2013. VO2 is transparent like glass at 30 degrees Celsius, and reflects infrared light when it reaches 60 OC. After further experimentation by the Berkeley team, the engineers discovered this unexpected and unusual property which opens up a galore of use-case possibilities.

Looking deeper into the material, the team found that electrons move within the vanadium dioxide’s crystal lattice in an absolutely synchronized way, so the heat that is generated as a side-effect is negligible. On regular metals, heat is created by electrons that hop around in a random fashion, but in VO2, this movement unfolds in a wholly tuned and marching-like manner. At this moment, the team is experimenting with the addition of more substances into the bizarre metal, achieving a controlled regulation of thermal conductivity properties in the material. Tungsten was confirmed to be working well with VO2, but more materials will be tested as the team aims to develop a set of different-purpose VO2-based materials for every application.

Image: Karl-Ludwig Poggemann/Flickr, CC BY 2.0