Gas-sensitive electrical properties of perovskite-type SmFeO3 thick films

Abstract Ultrafine SmFeO 3 powders have been prepared by the thermal decomposition at 700°C of the corresponding hexacyanocomplex, Sm[Fe(CN) 6 ]·4H 2 O. These powders have been used for the preparation of thick films, screen-printed on alumina substrates with comb-type Au electrodes. The electrical response of the films fired at 750°C, in N 2 and air atmospheres, prepared from pastes with different composition of the organic vehicle (o.v.), showed that they were sensitive to CO and NO 2 in dry and wet air. The composition of the o.v. strongly influenced the electrical conductivity and its activation energy and the gas response of the SmFeO 3 films, which had similar microstructure. The presence in the o.v. of components with hydroxyl groups causes a reaction with adsorbed oxygen species, which results in an increase in the films resistivity, being SmFeO 3 a p -type semiconductor and in their NO 2 response. The thick film processing parameters are thus of primary concern for the NO 2 sensing properties of the SmFeO 3 thick films.

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