Electron Probe Microanalysis of Ni Silicides Using Ni-L X-Ray Lines

We report electron probe microanalysis measurements on nickel silicides, Ni₅Si₂, Ni₂Si, Ni₃Si₂, and NiSi, which were done in order to investigate anomalies that affect the analysis of such materials by using the Ni L₃-M_4,5 line (Lα). Possible sources of systematic discrepancies between experimental data and theoretical predictions of Ni L₃-M_4,5 k-ratios are examined, and special attention is paid to dependence of the Ni L₃-M_4,5 k-ratios on mass-attenuation coefficients and partial fluorescence yields. Self-absorption X-ray spectra and empirical mass-attenuation coefficients were obtained for the considered materials from X-ray emission spectra and relative X-ray intensity measurements, respectively. It is shown that calculated k-ratios with empirical mass attenuation coefficients and modified partial fluorescence yields give better agreement with experimental data, except at very low accelerating voltages. Alternatively, satisfactory agreement is also achieved by using the Ni L₃-M₁ line (Lℓ) instead of the Ni L₃-M_4,5 line.