In the world of electronic materials there are two important material properties "electrical conductivity" and "thermal conductivity".

Generally speaking, as long as the electrical conductivity of the material is good enough, the thermal conductivity is also good. For example, copper, silver, aluminum and other metal materials have good electrical and thermal conductivity. Therefore, most metal materials have good electrical conductivity, and their thermal conductivity is very good. However, if the electrical conductivity is poor, does the thermal conductivity must be poor? Of course not. For example, non-conductive nano-diamond is one of the best thermal conductors among materials, and the thermal conductivity of diamond can be as high as 2300W/mK.

It is said that diamonds and rhinestones can be effectively distinguished by using the strong thermal conductivity of diamonds. The operation method: lick it with your tongue. If you feel the tip of your tongue is cool, it is a real drill; if it is warm, it is just a rhinestone; this wave of divine operation It is estimated that only a very sensitive tongue can do it.

heat transfer mechanism
When the temperature of one end of a solid material is higher than the other end, the phenomenon that heat automatically transfers from the hot end to the cold end is called heat conduction. . The mechanism of heat conduction is very complicated. In short, there are two main thermal conduction mechanisms for the heat conduction of solid materials. Metal materials mainly rely on electronic heat conduction, while non-metal materials mainly rely on lattice waves (phonons) of lattice vibration. , the photon heat transfer phenomenon may also exist at high temperature.

There are a large number of free electrons in the metal, and the mass of the electrons is also very light. When a part of the metal is heated, the energy of the free electrons in the heated part increases and the movement intensifies, constantly colliding with the metal ions and exchanging energy, transferring heat from a part to the whole metal. , so the metal has good thermal conductivity. The transfer of heat can be achieved quickly, therefore, metals generally have larger thermal conductivity. The reason why metals can generate current is that under the action of an external electric field, the free electrons in the metal will move in a direction to form a current.