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The oxidation of zirconium as observed by Auger electron spectroscopy: A comparison of experiment and density of state calculations
Author(s) -
Jungblut B.,
Sicking G.,
Papachristos T.
Publication year - 1988
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740130205
Subject(s) - auger , zirconium , spectral line , chemistry , analytical chemistry (journal) , fermi level , auger electron spectroscopy , atomic physics , range (aeronautics) , tetragonal crystal system , density of states , oxygen , materials science , electron , physics , condensed matter physics , crystallography , nuclear physics , inorganic chemistry , organic chemistry , chromatography , astronomy , composite material , crystal structure
Abstract Several investigators found by using standard AES equipment that the peak‐to‐peak heights of the Zr signals in the energy range between 80 eV and 170 eV vary in an unusual way after exposure of the sample to oxygen. 1–7 Normally the decrease of the Auger signal intensity is more pronounced for the metal signals of lower energy in comparison to those of higher energy. In contrast, in the case of Zr, an oxygen exposure leads to a strongly weakened 144 eV peak, whereas the signals in the energy range between 80 eV and 125 eV remain relatively unaffected. In order to study this phenomenon, a series of high resolution spectra on Zr and ZrO x specimens was taken. The corresponding data sets were processed by applying algorithms for background correction, smoothing, and deconvolution resulting in AES spectra, which are almost free from experimental broadening and loss process artifacts. As a result of this procedure, it becomes apparent that with increasing oxygen content an additional peak gradually appears 7 eV below the 144 eV Zr signal, whereas the signals between 80 eV and 125 eV show minor line shape effects. This new marked Auger transition can be explained by the formation of an oxygen 2p band which enables cross transitions and interatomic transitions to take place. This is confirmed by the density of state calculation performed for tetragonal ZrO 2 , 8 which reveals a O 2p band in the energy range from −4 eV to −8 eV below the Fermi level. Differentiated spectra of lower resolution, such as used for routine analysis, do not resolve these two signals and therefore show a broad peak of comparatively low intensity at 144 eV.