Although, the present

thermal conductivity of approximately 7.6 Wm−1 K−1 is still high for thermoelectric application, we anticipate that by using HPT processing combined with appropriate doping will result in further reduction of thermal conductivity of silicon and possibly other thermoelectric materials such as SiGe, Bi2Te3, and PbTe. Conclusions In summary, we demonstrated a novel way to reduce the lattice thermal conductivity of crystalline silicon by intense plastic strain through high-pressure torsion (HPT) at a pressure of 24 GPa. The grain boundary size decreases to nanoscale levels upon increasing the strain by HPT processing. The thermal conductivity of check details the HPT samples decreases to as low as approximately 7.6 Wm−1 K−1 due to the increase in phonon scattering at the nanograin boundaries. The present results introduce an efficient and irreversible way to make nanograin Selumetinib research buy boundaries and provide a potential tool for the fabrication of thermoelectric materials with improved performance. Acknowledgements This work was supported in part by a Grant-in-Aid for scientific research from the MEXT Japan, in Innovative areas ‘Bulk Nanostructured Metals’ (Nos. 22102004, 2510278). SH was financially supported by postdoctoral fellowship from Japan Society of Promotion of Science (JSPS) for foreign researchers. MK acknowledges the

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