General theory for designing phonon transport in alloyed/doped materials

摘要

Alloying/doping is a widely used technique for improving the electrical,mechanical,and optical properties of materials.However,this technology induces significant distortions in the lattice structure,mass distribution,and potential field,greatly enhancing phonon scattering.Here,we introduce the concept of alloying/doping path and employ crystal symmetry,lattice deformation,and electron distribution to characterize it.Based on this new concept,the phonon thermal transport behavior in alloyed/doped materials can be well designed,and along different alloying/doping paths,the difference in thermal conductivity can be up to 45 times.On one hand,strategic alloying/doping that combines high crystal symmetry,large lattice contraction,and the same electron distribution suppresses phonon-phonon scattering phase space,induces phonon stiffening,and bolsters electronic structure symmetry,respectively.These synergistic effects significantly improve thermal conductivity.On the other hand,random alloying/doping has a low symmetry,leading to the typical“U”shape of alloying/doping level-dependent thermal conductivity.Our theory is corroborated in three-dimensional(3D)Si,2D MoS_(2),and quasi-1D TiS_(3),affirming its efficacy and broad applicability in controlling phonon transport.