Radiation-induced segregation in a ceramic


Radiation-induced segregation is well known in metals, but has been rarely studied in ceramics. We discover that radiation can induce notable segregation of one of the constituent elements to grain boundaries in a ceramic, despite the fact that the ceramic forms a line compound and therefore has a strong thermodynamic driving force to resist off-stoichiometry. Specifically, irradiation of silicon carbide at 300 °C leads to carbon enrichment near grain boundaries, whereas the enrichment diminishes for irradiation at 600 °C. The temperature dependence of this radiation-induced segregation is different from that shown in metallic systems. Using an ab initio informed rate theory model, we demonstrate that this difference is introduced by the unique defect energy landscapes present in the covalent system. Additionally, we discover that grain boundaries in unirradiated silicon carbide grown by chemical vapour deposition are intrinsically carbon-depleted. The inherent grain boundary chemistry and its evolution under radiation are both critical for understanding the many properties of ceramics associated with grain boundaries.

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Fig. 1: STEM-HAADF images showing GBs in SiC.
Fig. 2: Local carbon concentrations in pristine 3C-SiC.
Fig. 3: Evolution of local carbon concentrations near irradiated GBs in 3C-SiC.
Fig. 4: RIS mechanism in SiC revealed by rate theory calculations.

Data availability

The data that support the findings of this study are publicly available at https://uwmadison.box.com/v/NM-RISinCeramic.

Code availability

The code used for calculating carbon concentrations at grain boundaries is provided in the Supplementary Information.


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The authors acknowledge the US Department of Energy Basic Energy Sciences for funding this research (fund number DE-FG02-08ER46493). The authors also acknowledge use of facilities and instrumentation supported by NSF through the University of Wisconsin Materials Research Science and Engineering Center (DMR-1720415). The electron microscopy research was conducted as part of a user project through Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy Office of Science User Facility.

Author information




I.S. conceived and directed the project, with considerable input from X.W. X.W., P.M.V. and I.S. designed the microscopy experiments. X.W., H.Z. and T.B. prepared the thin foils for the microscopy experiments. H.Z., T.B., Y.G., O.E. and T.K. fabricated the bicrystal SiC sample. H.Z. conducted the correlated tEBSD and TEM analysis. X.W., T.B. and J.I. performed the STEM-EELS measurements and data analysis. H.J. and C.L. carried out MD, DFT and CD calculations. X.W. developed the rate theory model for GB concentration calculations, with input from D.M. and I.S. X.W. and I.S. wrote the manuscript with help from all authors.

Corresponding authors

Correspondence to Xing Wang or Izabela Szlufarska.

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Supplementary information

Supplementary Information

Supplementary Notes 1–12, Figs. 1–12, Table 1 and source code of the self-developed algorithm for calculating grain boundary concentrations.

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Wang, X., Zhang, H., Baba, T. et al. Radiation-induced segregation in a ceramic. Nat. Mater. (2020). https://doi.org/10.1038/s41563-020-0683-y

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