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Solid Solution of Metal Dopants in Semiconducting β-FeSi2 Matrix

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Abstract:

Metal dopants are commonly used to improve the transport properties of semiconducting iron silicide (β-FeSi2). However, the formation of metallic phases is sensitive to the addition of dopants, especially when they reach their solubility limits. Those secondary phases negatively impact on the transport properties of the materials. In this study, the strategy to investigate the metal solubility in β-FeSi2 matrix based on crystal structure transition, phase fraction, and microstructural evolution was established. The X-ray diffraction results show that the peak intensity of the metallic phases (ε-FeSi and α-Fe2Si5) increases with increasing doping level. For Mn-doped β-Fe1−xMnxSi2, phase fraction analysis shows that the semiconducting β phase remains the dominant phase (>95%) up to x = 0.08, whereas metallic phases become dominant for x > 0.08. Although the β-phase persists up to x = 0.08, local compositional analysis reveals that the solubility of Mn within the β-phase decreases with increasing formation of secondary phases. The local elemental distribution analysis shows that Mn and Co, respectively, have a solid solution limit of ~6.3±0.1 % and ~8.8±0.7 % in β-FeSi2. It is found that Mn and Co have higher solubility than Ni. Our study provides insights into the strategy to probe the solubility of dopants, which could be beneficial for performance enhancement in semiconducting iron silicide systems.

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Periodical:

Key Engineering Materials (Volume 1062)

Pages:

19-36

DOI:

https://doi.org/10.4028/p-w8Tvdm

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Online since:

August 2026

Authors:

Sopheap Sam*, Kosuke Yamazaki, Hiroshi Nakatsugawa

Keywords:

Iron Silicide, Microstructure Evolution, Solubility Limit, Structural Transition

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© 2026 Trans Tech Publications Ltd. All Rights Reserved

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