CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

Chapter 5
formation of Cr 2 N was around 2 eV, and the shift in N1s binding energy was around 1 eV. In
Cr2p 3/2 region (Fig. 5.6a) the peak around 576.7 eV corresponds to the contribution from Cr 2 N,
and peak around 574.6 eV corresponds to the contribution of elemental chromium from the
stainless steel [163].
Fig. 5.5a: XPS spectra of chromium (Cr2p 3/2 ) region (dose 1×10 17 N + /cm 2 )
For N1s region (Fig. 5.5b) the peak around 397.5 eV is attributed to N1s in Cr 2 N
compound and, the peak around 398.6 is from elemental N1s region [163]. The preferential
formation of Cr 2 N at this dose is attributed to the lower free energy of formation (H f = -125.4
Joule/mole) as compared to CrN (H f = -122.9 Joule/mole), and iron nitrides (H f = -10.45
Joule/mole) even though iron is the major alloying element in austenitic stainless steel [164]. At
higher dose of 2.5×10 17 N + /cm 2 , the peak position observed for Cr2p 3/2 and N1s were sameThus,
with increase in dose of nitrogen ion implantation, chromium preferentially combines with