ESR study of influence of oxygen on molybdenum sulfides

• Published in: Journal of non-crystalline solids 1992-11, Vol.149 (3), p.218-228
• Main Authors: Bensimon, Y., Belougne, P., Deroide, B., Zanchetta, J.V., Giuntini, J.C., Henn, F.
• Format: Article
• Language: English
• Subjects: Color centers and other defects; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron paramagnetic resonance and relaxation; Exact sciences and technology; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Physics
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/0022-3093(92)90070-Z

Electron spin resonance (ESR) measurements of amorphous molybdenum sulfides MoS 2+ x (0 ≤ x ≤ 1) and their derived compounds MoS y O z , which are obtained by oxygen exposure at 130°C, are performed in order to determined the nature and the number of the active sites. The ESR spectrum is always the sum of three elementary signals, the responsible species of which are analyzed by means of a simulation program. These species can be related either to unsaturated sulfur atoms or to Mo V atoms within two different surroundings. The strong modification of the ESR spectra, around the composition MoS 2.6, can be considered as a “pseudo-transition”. The influence of oxygen exposure confirms this assumption and leads to an increasing number of paramagnetic defects in accordance with the catalytic properties of these solids.