M. Guemmaz et al., Electronic changes induced by vacancies on spectral and elastic propertiesof titanium carbides and nitrides, J ELEC SPEC, 107(1), 2000, pp. 91-101
Citations number
55
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA
Substoichiometric carbides TiC0.49+ TiC0.78 and nitrides TiN0.45 TiN0.61 ha
ve been synthesized by multiple energy ion implantation of C+ and N+ in pol
ycrystalline titanium. Here, we review theoretical and experimental results
concerning the electronic structure of these compounds with various degree
s of vacancies. The valence band X-ray photoemission spectra (v-XPS) as wel
l as core level XPS suggest important changes of the electronic structure i
n comparison to the corresponding stoichiometric compounds. New structures
appear near the Fermi level in the experimental v-XPS spectra in agreement
with tight-binding-linear-muffin-tin-orbitals (TB-LMTO) calculations of the
electronic densities of states (DOS). These structures, absent in stoichio
metric compounds, are interpreted as resulting from Ti-Ti bond states betwe
en neighbouring titanium atoms through vacancies induced by substoichiometr
y along the whole range of vacancy concentration. Moreover, these bond modi
fications explain the experimental changes of Young's modulus, observed by
nanoindentation, in substoichiometric titanium carbides and nitrides. (C) 2
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