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Atomistic Understanding of the Formation, Structure, and Decomposition of an Fe4C Iron Carbide Phase on a Copper Substrate

Author
Abstract
Having an atomistic understanding of the formation and structural characteristics of bulk and surface iron carbide phases plays a crucial role in comprehending the mechanisms of phase transformation, microstructure formation, and surface reconstructions in the development of advanced materials with improved magnetic, mechanical, and catalytic properties. This study uses synchrotron (SR) and angle-resolved (AR) XPS, STM, LEED, and theoretical calculations (DFT) with the aim to provide a detailed experimental and theoretical discussion on the formation, stabilization, structure, and decomposition of Fe4C iron carbide. FCC(100) Fe4C iron carbide multilayer films were prepared on Cu(100) by evaporating iron in the presence of an ethylene atmosphere. Angle-resolved XPS measurements reveal that surface and interior carbon can be distinguished due to their appearance at different binding energies and reveal that the surface consists of Fe2C while the bulk has Fe4C stoichiometry. LEED and STM measurements show that the surface exhibits the p4g(2 × 2) clock reconstruction. Theory simulations show that the bulk Fe4C iron carbide has a constrained crystal lattice with alternating Fe and Fe4C2 layers, which grow in a pseudomorphic way on the copper. The carbide phase is stable up to 700 K. Above this temperature, iron diffuses into the copper while carbon remains on the surface, where it forms graphite.
Year of Publication
2023
Journal
Journal of Physical Chemistry C
Volume
127
Issue
26
Number of Pages
12811-12820
DOI
10.1021/acs.jpcc.3c03134
Dataset
10.1021/acs.jpcc.3c03134
PId
08f77e071c7ad5cb3909ad551256f8a9
Alternate Journal
J. Phys. Chem. C
Journal Article
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