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We examine the validity of assumptions commonly used for the analysis of bonds (bond fractions) in amorphous W-B-C systems by a deconvolution procedure applied on measured XPS profiles. We focus on the relationship between the chemical shift of 4f electronic states of W atoms and the relative amounts of W-X bonds (X=W, B, C). The bond fraction analysis of amorphous W-B-C assumes that the formation of binary W–B and W–C bonds leads to a shift of 4f electron binding energies to lower and higher values, respectively, due to the differences in the Pauling electronegativity of W, B and C. Different W-B-C compositions also lead to different relative amounts of W-W bonds but their effect on the chemical shift is usually neglected. To test these assumptions we generated amorphous W-B-C atomic model of W40B30C30 composition (atomic percent), calculated the W 4f core electron binding energies from ab initio methods and examined relationships between the W-X bonds and the chemical shift of 4f electron binding energies. Our analysis confirms the expected chemical shifts in W-B-C caused by W-C bonds. Additionally, we found a correlation between W-W bonds and W 4f electronic states and discuss its influence on the bond fraction analysis.
Keywords: XPS, bonds, amorphous materials, atomistic model© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.