Role of grain boundaries as phonon diffraction gratings in the theory of thermal conductivity

Article

关键词: AMORPHOUS MATERIALS;    SOLIDS;    TEMPERATURE;    GLASSES;    HEAT;    TRANSPORT;   

DOI  :  10.1103/PhysRevB.61.6677

来源: SCIE

【 摘 要 】

The picture of a grain boundary as a periodic array of dislocations implies the occurrence of phonon scattering processes that the Klemens theory of thermal conductivity does not account for. A grain boundary works similar to a diffraction grating, producing diffraction spectra of various orders: each order number n is associated with a class of scattering processes contributing to thermal resistance. The Klemens theory corresponds to n=0: it is shown that processes with n not equal 0 are essential to explain the heat transport properties of a specimen containing grain boundaries. The theory is used to explain the behavior of thermal conductivity, both in the range below 5 K and in the region of the conductivity peak, as observed in crystals of lithium fluoride, alumina, and quartz. It is also applied to the conductivity curve of fused silica, in the frame of a model where a glass is pictured as a solid with a high-density distribution of grain boundaries.

【 授权许可】

Free