Abstract
Engineering microstructural defects, like grain boundaries, offers superior control over transport properties in energy materials. However, technological advancement requires establishing microstructure-property relations at the micron or finer scales, where most of these defects operate. Here, the first experimental evidence of thermal resistance for individual silicon grain boundaries, estimated with a Gibbs excess approach, is provided. Coincident site lattice boundaries exhibit uniform excess thermal resistance along the same boundary, but notable variations from one boundary to another. Boundaries associated with low interface energy generally exhibit lower resistances, aligning with theoretical expectations and previous simulations, but several exceptions are observed. Transmission electron microscopy reveals that factors like interface roughness and presence of nanotwinning can significantly alter the observed resistance, which ranges from ∼0 to up to ∼2.3 m2K/GW. In stark contrast, significantly larger and less uniform values - from 5 to 30 m2K/GW - are found for high-angle boundaries in spark-plasma-sintered polycrystalline silicon. Further, finite element analysis suggests that boundary planes that strongly deviate from the sample vertical (beyond ∼45°) can show up to 3-times larger excess resistance. Direct correlations of properties with individual defects enable the design of materials with superior thermal performance for applications in energy harvesting and heat management.
| Original language | English (US) |
|---|---|
| Journal | Advanced Functional Materials |
| DOIs | |
| State | Accepted/In press - 2024 |
Funding
E.I. and S.J. contributed equally to this work. The authors would like to acknowledge Dr. Tamboli and Dr. Page of the National Renewable Energy Laboratory for providing the samples, as well as Dr. Abbott at Northwestern University and Prof. Boehlert at Michigan State University for support with sample preparation and imaging. This work was supported by the Northwestern University Center for Engineering Sustainability and Resilience through the Seed\u2010funded project \u201CToward Engineering Metamaterials for Sustainable Energy Solutions: Local Thermal Properties of Grain Boundaries in Polycrystalline Materials.\u201D O.B. acknowledges support from the National Science Foundation (NSF) under the grant numbers, NSF DMR\u20102117727, and NSF DMR\u20101720139 for the Materials Research Science and Engineering Center (MRSEC) of Northwestern University. G.J.S. acknowledges the support of award 70NANB19H005 from the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD). A.Z. acknowledges funding from NSF DMR\u20102118463. J.S. and R. N. acknowledge support from the Japan Science and Technology Agency, under the program JST CREST grant No. JPMJCR21O2. This work made use of the EPIC, SPID, and NUFAB facilities of Northwestern University's NUANCE Center, which received support from the SHyNE Resource (NSF ECCS\u20102025633), the IIN, and Northwestern's MRSEC program (NSF DMR\u20102308691).
Keywords
- coincident site lattices
- grain boundaries
- multicrystalline silicon
- structure-property relations
- thermal conductivity imaging
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Chemistry
- Biomaterials
- General Materials Science
- Condensed Matter Physics
- Electrochemistry