The electronic contribution to the thermal conductivity can be deduced from the electrical conductivity through the use of the Wiedemann-Franz law. However, the thermal conductivity due to phonon heat transfer cannot be measured directly. 自由电子引起的热导率可以通过电导率,利用Wiedemann-Franz定律得到,声子引起的热导率目前仍然不能进行实验测量,只能借助其他方法来研究。