Thermal conductivity reduction of crystalline silicon by high-pressure torsion

Sivasankaran Harish, Mitsuru Tabara, Yoshifumi Ikoma, Zenji Horita, Yasuyuki Takata, David G. Cahill, Masamichi Kohno

Research output: Contribution to journalArticlepeer-review


We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk crystalline silicon when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity of the HPT-processed samples were measured using picosecond time domain thermoreflectance. Thermal conductivity measurements show that the HPT-processed samples have a lattice thermal conductivity reduction by a factor of approximately 20 (from intrinsic single crystalline value of 142 Wm-1 K-1 to approximately 7.6 Wm-1 K-1). Thermal conductivity reduction in HPT-processed silicon is attributed to the formation of nanograin boundaries and metastable Si-III/XII phases which act as phonon scattering sites, and because of a large density of lattice defects introduced by HPT processing. Annealing the samples at 873 K increases the thermal conductivity due to the reduction in the density of secondary phases and lattice defects.

Original languageEnglish (US)
Article number326
Pages (from-to)1-5
Number of pages5
JournalNanoscale Research Letters
Issue number1
StatePublished - 2014


  • High-pressure torsion
  • Silicon thermal conductivity
  • Thermoelectrics
  • Time domain thermoreflectance

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics


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