Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7147314 | Sensors and Actuators B: Chemical | 2014 | 7 Pages |
Abstract
The appropriate doping of Ca in nanocrystalline LaFeO3 not only reduces the electrical resistance, but also enhances the sensing response. A minimum of resistance for nanocrystalline La1âxCaxFeO3 (x = 0-0.35) occurs at about x = 0.3 with a value of Fe4+/Fe3+â1. The electrical conduction of La1âxCaxFeO3 (x = 0-0.35) can be well described by the mechanism of small polaron hopping. Results of X-ray photoelectron spectroscopy (XPS) show that the proportion of adsorbed oxygen Oads enhances monotonously with Ca doping from x = 0-0.35. However, there exists an optimal Ca content (about x = 0.2) for obtaining highest response to 200 ppm CO among La1âxCaxFeO3-based sensors (0â¤xâ¤0.35). Such results indicate that some parts of adsorbed oxygen species do not effectively release their electrons to the surface of La1âxCaxFeO3 at higher Ca dopants. The gas sensing response to CO for La1âxCaxFeO3 sensors depends not only upon the amount of adsorbed oxygen on grain surfaces of sensors, but also upon the desorption capabilities of adsorbed oxygen species through reacting with CO.
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Authors
Changmin Shi, Hongwei Qin, Ming Zhao, Xiaofeng Wang, Ling Li, Jifan Hu,