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Titolo:
Design of ceramic materials for chemical sensors: Effect of SmFeO3 processing on surface and electrical properties
Autore:
Aono, H; Sato, M; Traversa, E; Sakamoto, M; Sadaoka, Y;
Indirizzi:
Ehime Univ, Fac Engn, Dept Mat Sci & Engn, Matsuyama, Ehime 7908577, JapanEhime Univ Matsuyama Ehime Japan 7908577 Matsuyama, Ehime 7908577, Japan Univ Roma Tor Vergata, Dipartimento Sci & Tecnol Chim, I-00133 Rome, ItalyUniv Roma Tor Vergata Rome Italy I-00133 ecnol Chim, I-00133 Rome, Italy Yamagata Univ, Fac Sci, Dept Mat & Biol Chem, Yamagata 9908560, Japan Yamagata Univ Yamagata Japan 9908560 Biol Chem, Yamagata 9908560, Japan
Titolo Testata:
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
fascicolo: 2, volume: 84, anno: 2001,
pagine: 341 - 347
SICI:
0002-7820(200102)84:2<341:DOCMFC>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
PEROVSKITE-TYPE OXIDES; NANOSIZED LAFEO3 POWDERS; FILM GAS SENSORS; THERMAL-DECOMPOSITION; HETERONUCLEAR COMPLEXES; ELECTROCERAMIC APPLICATIONS; THICK-FILMS; HO; EVOLUTION; BEHAVIOR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
28
Recensione:
Indirizzi per estratti:
Indirizzo: Sadaoka, Y Ehime Univ, Fac Engn, Dept Mat Sci & Engn, Matsuyama, Ehime 7908577, Japan Ehime Univ Matsuyama Ehime Japan 7908577 Ehime 7908577, Japan
Citazione:
H. Aono et al., "Design of ceramic materials for chemical sensors: Effect of SmFeO3 processing on surface and electrical properties", J AM CERAM, 84(2), 2001, pp. 341-347

Abstract

Perovskite-type SmFeO3 powders were prepared by the thermal decomposition of a heteronuclear complex, Sm(Fe(CN)(6)). 4H(2)O and by solid-state reaction between the corresponding single oxides, Sm2O3 and Fe2O3. The thermal decomposition behavior of the complex was studied by thermogravimetric analysis. X-ray diffractometry was used to investigate the structure of the products from the complex thermal decomposition and the formation of SmFeO2 fromthe oxide mixture. Powders prepared by both methods were used to deposit thick films onto alumina substrates with comb-type gold electrodes. The microstructure and chemical homogeneity of the film surfaces,were investigated by scanning electron microscopy and Auger electron spectroscopy. Thick SmFeO3 single-phase films having a homogeneous elemental distribution on the surface were obtained when powder prepared by thermal decomposition of the complex was used for deposition, even when the powder was fired at low temperature (800 degreesC), Surface chemical analysis was performed by X-ray photoelectron spectroscopy (XPS), The O Is XPS line was deconvoluted into two peaks, attributed to adsorbed oxygen (O-ad) and oxygen in the lattice (O-lattice). Quantitative analysis showed that the surface coverage of iron, expressed as Fe/(Fe + Sm), was larger for the films prepared using the solid-state reacted powder. Although the O-lattice/(Fe + Sm) atomic ratio was not influenced by the processing procedures (and, thus, by iron surface coverage), the amount of O-ad decreased with increasing iron surface coverage, A model of the SmFeO3 surface was used to determine that the outermost layer ofthe perovskite-type SmFeO3 prepared from the complex consisted mainly of samarium ions that could each bond four adsorbed oxygen ions. A single oxygen ion could adsorb onto an iron ion, and therefore, the content of adsorbedoxygen was lower for the film prepared from the solid state reacted powders, which showed larger iron surface coverage. Electrical conductance measurements, performed with increasing temperature in different gaseous environments, confirmed these findings. Higher conductances and lower activation energies were observed for the films with larger samarium surface coverage.

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Documento generato il 01/04/20 alle ore 00:51:37