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Thermogravimetric investigation of oxygen deficiency in SnO 2 reduced at 500 °C or below
- Source :
- Solid State Ionics. 308:101-106
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- The oxygen deficiency of SnO 2 was investigated by thermogravimetric analysis (TGA). The powder samples were reduced in 0.5% H 2 /N 2 at 200–500 °C and, their weight changes were evaluated by TGA under flowing O 2 . The results showed that the response of SnO 2 against H 2 /N 2 differed from that against H 2 /air, which is the gas mixture typically used to evaluate SnO 2 -based gas sensors. The subsequently obtained TGA traces of the powders reduced under H 2 /N 2 showed two stepwise weight gains. The first weight gain began near room temperature and ended at approximately 200 °C. The second weight gain was observed between 400 and 600 °C, which became prominent when the sample was reduced at 400 °C or above. The existence of two types of oxygen sites was deduced from the temperature dependence of the weight changes in the TGA traces and they were related to the positions of oxygen sites in the surface and bulk regions. SnO 2 was tolerant to the oxygen deficiency, and the extent of deficiency was dependent on the crystallinity and the grain size. For example, the composition of SnO 2 precipitated in SnF 2 aqueous solution through a hydrolysis reaction was estimated to be SnO 1.94 after the reduction at 400 °C in 0.5% H 2 /N 2 . Small grains with lower crystallinity tended to accept greater oxygen deficiency under a certain condition.
- Subjects :
- Thermogravimetric analysis
Aqueous solution
Chemistry
Analytical chemistry
chemistry.chemical_element
Mineralogy
02 engineering and technology
General Chemistry
Oxygen deficiency
021001 nanoscience & nanotechnology
Condensed Matter Physics
01 natural sciences
Oxygen
Grain size
Hydrolysis
Crystallinity
0103 physical sciences
General Materials Science
Composition (visual arts)
010306 general physics
0210 nano-technology
Subjects
Details
- ISSN :
- 01672738
- Volume :
- 308
- Database :
- OpenAIRE
- Journal :
- Solid State Ionics
- Accession number :
- edsair.doi...........a0dbd3f2c3b5160c6f4a193bee7e86e4