Thermal conductivity the list of thermal conductivities. These should be considered approximate due to the uncertainties related to material definitions. High energy generation rates within electronics or turbines require the use of materials with high thermal conductivity such as copper "(see: Copper in heat exchangers)", aluminium, and silver. On the other hand, materials with low thermal conductance, such as polystyrene foam and fire brick, are used in building construction or in furnaces in an effort to slow the flow of heat, i.e. for insulation purposes. The reciprocal of thermal conductivity is "thermal resistivity", usually expressed in kelvin-meters per watt (K⋅m⋅W). For a
Wiedemann–Franz law the Wiedemann–Franz law. A Berkeley-led study in 2016 by Lee "et al." also found a large violation of the Wiedemann–Franz law near the insulator-metal transition in VO nanobeams. In the metallic phase, the electronic contribution to thermal conductivity was much smaller than what would be expected from the Wiedemann–Franz law. The results can be explained in terms of independent propagation of charge and heat in a strongly correlated system. Wiedemann–Franz law In physics, the Wiedemann–Franz law states that the ratio of the electronic contribution of the thermal conductivity ("κ") to the electrical conductivity ("σ") of a metal is proportional to