Spectroscopic and spectromagnetic studies were performed on SiO 2 obtained by hydrolytic condensation of tin(IV) alkoxide, Sn(OtBu) 4. Tin dioxide was produced in powder form, suitable for spectroscopic investigation, and it could also be used as base material for thin film gas sensors. Electron paramagnetic resonance (EPR) spectroscopy allowed to detect singly ionized paramagnetic oxygen vacancies (V 0*), produced by interaction of SnO 2 with carbon monoxide in the range of temperature 298-773 K. The interaction with CO at T<173 also reduced some Sn(IV) centres to Sn(II), by transfer of electrons from the oxygen vacancies to Sn(IV). This was detected by X-ray Photoelectron Spectroscopy (XPS) in the Valence Band region. Moisture too, when present in the atmosphere, was found to form paramagnetic oxygen vacancies. In the presence of air the formation of vacancies due to CO interaction, and their reaction with molecular oxygen occurred at the same time. Below 473 K the saturation of vacancies was due to chemisorbed paramagnetic O 2- , while above 473 K it was from diamagnetic O 2$
Canevali, C., Chiodini, N., Di Nola, P., Morazzoni, F., Scotti, R., Bianchi, C. (1997). Electron paramagnetic resonance and X-ray photoelectron spectroscopy studies of SnO 2 obtained by sol-gel process. In Conference Proceedings Vol 54 Sensors for Advanced Applications '96 National Meeting on Sensors for Advanced Applications.
Electron paramagnetic resonance and X-ray photoelectron spectroscopy studies of SnO 2 obtained by sol-gel process
CANEVALI, CARMEN;CHIODINI, NORBERTO;MORAZZONI, FRANCA;SCOTTI, ROBERTO;
1997
Abstract
Spectroscopic and spectromagnetic studies were performed on SiO 2 obtained by hydrolytic condensation of tin(IV) alkoxide, Sn(OtBu) 4. Tin dioxide was produced in powder form, suitable for spectroscopic investigation, and it could also be used as base material for thin film gas sensors. Electron paramagnetic resonance (EPR) spectroscopy allowed to detect singly ionized paramagnetic oxygen vacancies (V 0*), produced by interaction of SnO 2 with carbon monoxide in the range of temperature 298-773 K. The interaction with CO at T<173 also reduced some Sn(IV) centres to Sn(II), by transfer of electrons from the oxygen vacancies to Sn(IV). This was detected by X-ray Photoelectron Spectroscopy (XPS) in the Valence Band region. Moisture too, when present in the atmosphere, was found to form paramagnetic oxygen vacancies. In the presence of air the formation of vacancies due to CO interaction, and their reaction with molecular oxygen occurred at the same time. Below 473 K the saturation of vacancies was due to chemisorbed paramagnetic O 2- , while above 473 K it was from diamagnetic O 2$
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