کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
751227 895212 2010 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
From doping to phase transformation: Ammonia sensing performances of chloroalkoxide-derived WO3 powders modified with chromium
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
From doping to phase transformation: Ammonia sensing performances of chloroalkoxide-derived WO3 powders modified with chromium
چکیده انگلیسی

WO3 precursor solutions were prepared by methanolysis of WCl6 in presence of acetylacetone as a stabilizer. Chromium addition was achieved by mixing Cr 2-ethylhexanoate with the pure solutions, with Cr: W atomic concentrations ranging from 2% to 22%. Powders were prepared by drying the solutions and heat-treating the product up to 700 °C. After heat-treating at 400 °C, crystalline WO3 was obtained, and X-ray diffraction and Transmission Electron Microscopy showed that the powders were constituted by a mixture of the WO3 monoclinic and triclinic crystallographic phases. The Cr-modified samples, with a Cr concentration of at least 5%, presented the additional phase Cr2WO6. Structural investigations suggested that this phase was favored instead of chromium oxides due to the incorporation of Cr in the WO3 lattice in interstitial position. The sensing tests towards ammonia gas, in concentrations ranging from 50 to 500 ppm, showed that, up to 5% concentration, Cr addition is beneficial in lowering the best operating temperatures and/or improving the response with respect to the pure powders. For higher Cr concentrations, the response severely decays. This result was interpreted in terms of the Cr2WO6 grains and of the influence of lowered concentration of interstitial Cr on the oxygen vacancies.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Sensors and Actuators B: Chemical - Volume 148, Issue 1, 30 June 2010, Pages 200–206
نویسندگان
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