The influence of nonstoichiometry on electrical transport and ethanol sensing characteristics for nanocrystalline LaFexO3-δ sensors
The influence of nonstoichiometry on electrical transport and ethanol sensing characteristics for nanocrystalline LaFexO3-δ sensors
复制标题
非化学计量对纳米晶 LaFexO3 δ 传感器的电输运和乙醇传感特性的影响
DOI：
10.1016/j.snb.2016.02.096
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发表时间：
2016-07-01
影响因子：
8.4
通讯作者：
Peng, Hua
中科院分区：
文献类型：
--
作者：
Cao, Kang;Cao, Ensi;Peng, Hua
以柠檬酸为溶剂，采用溶胶-凝胶法制备了非化学计量比的LaFexO 3-δ（x = 0.7/0.8/0.9/1.0/1.1/1.2/1.3）纳米晶粉末。LaFexO 3- delta传感器电阻的温度依赖性最符合小极化子跳跃传导的Holsteins模型。电阻是由电子价态补偿和氧空位补偿之间的竞争决定的。在同一温度下，随着缺铁量的增加，电阻下降。XPS对O 1 s和Cl s谱的分析证实了表面碳酸镧的存在。结合表面吸附氧和碳酸镧浓度、Fe ~（4+）/Fe ~（3+）原子比和Fe/La原子比随x值的变化，讨论了LaFexO_（3-δ）传感器对乙醇的响应，表明除了吸附氧物种的贡献外，单齿碳酸镧分解释放的天然活性氧捕获的电子也对传感器的响应有贡献。纳米晶LaFe_（0.8）O_（3-δ）传感器的最佳传感性能归因于其相对大的表面吸附氧物种和单齿碳酸镧浓度。(C)© 2016 Elsevier B. V.版权所有。
Nonstoichiometric nanocrystalline LaFexO3 - delta(x = 0.7/0.8/0.9/1.0/1.1/1.2/1.3) powers were prepared by sol-gel method with citric acid. Temperature dependence of resistance for LaFexO3 - delta sensors fits best to Holsteins model of small polaron hopping conduction. The resistance is determined by the competition between electrical valence compensation and oxygen vacancy compensation. And at each fixed temperature, the resistance is decreased with the introduction of more Fe deficiency. XPS analysis on O1s and Cl s spectra verifies the existence of La-carbonate on the surface. The variation of surface concentration of adsorbed oxygen and La-carbonate, atomic ratio of Fe4+/Fe3+ and Fe/La with x value are discussed in combination, which indicate that the release of electrons trapped by native active oxygen due to the decomposition of monodentate La-carbonate also makes contribution to the response of LaFexO3 - delta sensors to ethanol, in addition to the major contribution from adsorbed oxygen species. The best sensing performance of nanocrystalline LaFe0.8O3 - delta sensor is ascribed to its relatively large surface concentration of adsorbed oxygen species and monodantate La-carbonate. (C) 2016 Elsevier B.V. All rights reserved.