TY  - JOUR
A1  - Kojda, Danny
A1  - Hofmann, Tommy
A1  - Gostkowska-Lekner, Natalia Katarzyna
A1  - Habicht, Klaus
T1  - Characterization and modeling of the temperature-dependent thermal conductivity in sintered porous silicon-aluminum nanomaterials
JF  - Nano research
N2  - Nanostructured silicon and silicon-aluminum compounds are synthesized by a novel synthesis strategy based on spark plasma sintering (SPS) of silicon nanopowder, mesoporous silicon (pSi), and aluminum nanopowder. The interplay of metal-assisted crystallization and inherent porosity is exploited to largely suppress thermal conductivity. Morphology and temperature-dependent thermal conductivity studies allow us to elucidate the impact of porosity and nanostructure on the macroscopic heat transport. Analytic electron microscopy along with quantitative image analysis is applied to characterize the sample morphology in terms of domain size and interpore distance distributions. We demonstrate that nanostructured domains and high porosity can be maintained in densified mesoporous silicon samples. In contrast, strong grain growth is observed for sintered nanopowders under similar sintering conditions. We observe that aluminum agglomerations induce local grain growth, while aluminum diffusion is observed in porous silicon and dispersed nanoparticles. A detailed analysis of the measured thermal conductivity between 300 and 773 K allows us to distinguish the effect of reduced thermal conductivity caused by porosity from the reduction induced by phonon scattering at nanosized domains. With a modified Landauer/Lundstrom approach the relative thermal conductivity and the scattering length are extracted. The relative thermal conductivity confirms the applicability of Kirkpatrick's effective medium theory. The extracted scattering lengths are in excellent agreement with the harmonic mean of log-normal distributed domain sizes and the interpore distances combined by Matthiessen's rule.
KW  - thermal conductivity
KW  - mesoporous silicon
KW  - porosity
KW  - spark plasma
KW  - sintering
KW  - nanoscale modeling
Y1  - 2022
U6  - https://doi.org/10.1007/s12274-022-4123-y
SN  - 1998-0124
SN  - 1998-0000
VL  - 15
IS  - 6
SP  - 5663
EP  - 5670
PB  - Tsinghua Univ. Press
CY  - Beijing
ER  -