Abstract

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 degrees C. After heat-treating at 400 degrees 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.

Autore Pugliese

• Epifani Mauro Salvatore , Siciliano Pietro Aleardo

Tutti gli autori

• Epifani M.; Andreu T.; Magana C.R.; Diaz R.; Arbiol J.; Siciliano P.; Morante J.R.

Titolo volume/Rivista

Sensors and actuators. B, Chemical

Anno di pubblicazione

2010

ISSN

0925-4005

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

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Numero di citazioni Scopus

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Ultimo Aggiornamento Citazioni

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Settori ERC

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Codici ASJC

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