Effect of lattice defects, hydrogen impurity and temperature on electronic thermal conductivity in first wall tungsten materials

Significant changes in the microstructure of the first wall tungsten (W) materials caused by intense particle irradiation from the plasma in fusion reactors should affect the thermal property of the first wall materials. Although it has been established that for metals including W, the electrons contained therein play a major role in heat transport, few theoretical studies have focused on the heat transport performance by electrons of the defective tungsten. In this work, we have intensively investigated the effect of irradiated defects and temperature on the electronic thermal conductivity of tungsten by the tight-binding (TB) potential model. It is found that the electronic transport performance of tungsten crystals with different defects, such as point defects, voids, or hydrogen (H) impurities, degrades with increasing defect concentration, where the greatest reduction is caused by the randomly-distributed point defects and the smallest by H at the same defect concentration. Importantly, filling H in the void is beneficial to reduce the scattering of the void against electrons and improve electronic transport performance. As the temperature rises, the electrical conductivity decreases, but the electronic thermal conductivity increases. The behavior in the electronic thermal conductivity is attributed to the additional ‘gain effect’ of temperature on the electronic thermal conductivity compared to the electrical conductivity. Besides, it is inferred that the weaker the electron scattering caused by defects, the slighter the response of electronic thermal conductivity to temperature. For all concerned systems, the changes in their electronic transport performance can be understood through our calculated electron mean free path (MFP).