TY - JOUR
T1 - Phonon transport in multiphase nanostructured silicon fabricated by high-pressure torsion
AU - Shao, Cheng
AU - Matsuda, Kensuke
AU - Ju, Shenghong
AU - Ikoma, Yoshifumi
AU - Kohno, Masamichi
AU - Shiomi, Junichiro
N1 - Funding Information:
This research was funded in part by JSPS KAKENHI (Grant Nos. 19H00744, 18H01384, 19K14902), JST CREST (Grant No. JPMJCR20Q3), and the National Natural Science Foundation of China (Grant No. 52006134). The calculations in this work were performed using supercomputer facilities of the Institute for Solid State Physics, the University of Tokyo.
Publisher Copyright:
© 2021 Author(s).
PY - 2021/2/28
Y1 - 2021/2/28
N2 - We present a combined experimental and numerical investigation of phonon transport in multiphase nanostructured silicon. The sample was synthesized by high-pressure torsion with a nominal pressure of 24 GPa. Based on the x-ray diffraction measurement, we have identified the existence of three phases of silicon in the sample: Si-I, Si-III, and Si-XII, with volume fractions of 66%, 25%, and 9% and average grain sizes of 25, 14, and 11 nm, respectively. The measured thermal conductivities of the sample in the temperature range of 150-330 K are on the order of 5 W/(m K) and exhibit weak temperature dependence. A multiscale modeling that incorporates first-principles lattice dynamics, the Monte Carlo ray-tracing method, and effective medium theory was used to understand the mechanism of phonon transport in multiphase nanostructured silicon as well as the weak temperature dependence. We found that the thermal conductivity of single-phase nanostructured silicon decreases with decreasing average grain size and is about an order of magnitude lower than the corresponding bulk counterpart when the average grain size is O (10 nm). The weak temperature-dependent thermal conductivity in the nanostructured silicon is attributed to the strong elastic phonon-boundary scattering at the grain boundary. The thermal conductivity predicted from the multiscale modeling matches reasonably well with the measurement. This work provides insights into phonon transport in multiphase nanostructured materials and suggests that the effective thermal conductivity of nanostructured silicon from high-pressure torsion can be further reduced by increasing the volume fractions of the Si-III and Si-XII phases.
AB - We present a combined experimental and numerical investigation of phonon transport in multiphase nanostructured silicon. The sample was synthesized by high-pressure torsion with a nominal pressure of 24 GPa. Based on the x-ray diffraction measurement, we have identified the existence of three phases of silicon in the sample: Si-I, Si-III, and Si-XII, with volume fractions of 66%, 25%, and 9% and average grain sizes of 25, 14, and 11 nm, respectively. The measured thermal conductivities of the sample in the temperature range of 150-330 K are on the order of 5 W/(m K) and exhibit weak temperature dependence. A multiscale modeling that incorporates first-principles lattice dynamics, the Monte Carlo ray-tracing method, and effective medium theory was used to understand the mechanism of phonon transport in multiphase nanostructured silicon as well as the weak temperature dependence. We found that the thermal conductivity of single-phase nanostructured silicon decreases with decreasing average grain size and is about an order of magnitude lower than the corresponding bulk counterpart when the average grain size is O (10 nm). The weak temperature-dependent thermal conductivity in the nanostructured silicon is attributed to the strong elastic phonon-boundary scattering at the grain boundary. The thermal conductivity predicted from the multiscale modeling matches reasonably well with the measurement. This work provides insights into phonon transport in multiphase nanostructured materials and suggests that the effective thermal conductivity of nanostructured silicon from high-pressure torsion can be further reduced by increasing the volume fractions of the Si-III and Si-XII phases.
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U2 - 10.1063/5.0037775
DO - 10.1063/5.0037775
M3 - Article
AN - SCOPUS:85101535932
VL - 129
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 8
M1 - 085101
ER -