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Investigation on Oxygen Resistance Properties of RBaCo2O5+δ Ceramics

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Author(s): SONG Hong-Zhang, QIN Zhen, GAO Feng, JIA Jian-Feng, YANG De-Lin, HU Xing

Journal: Journal of Inorganic Materials
ISSN 1000-324X

Volume: 27;
Issue: 8;
Start page: 887;
Date: 2012;
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Keywords: RBaCo2O5+δ ceramics; surrounding oxygen pressure; varistors; sensors

ABSTRACT
RBaCo2O5+δ (R=Y, Dy, Gd, Pr, Nd, Sm, and Eu) ceramics were synthesized by the solid-state reaction method. Their resistivities depending on temperature were investigated by the standard four-probe method from room temperature to 600¡䬠At low temperature, all the resistivities decrease with the rising temperature, and exhibit semiconducting behavior. After the resistivities reach minimum values at certain temperatures, they increase slowly with temperature, and exhibit semimetal conducting behavior. Especially, the resistivity variations of RBaCo2O5+δ samples with the change of atmosphere at constant temperatures are studied. The results show that RBaCo2O5+δ could be potential oxygen resistance sensor materials, and that the responding rates of RBaCo2O5+δ are YBaCo2O5+δ > DyBaCo2O5+δ > GdBaCo2O5+δ > PrBaCo2O5+δ > NdBaCo2O5+δ > SmBaCo2O5+δ > EuBaCo2O5+δ. For YBaCo2O5+δ, the resistivity rises quickly due to the oxygen desorption when the atmosphere is switched from oxygen to nitrogen at 700¡䪠and reaches its maximum equilibrium value within 90 s. In addition, the resistivity drops drastically due to the oxygen adsorption when the nitrogen atmosphere is switched to oxygen, and reaches its minimum equilibrium value within 30 s.

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Tangokurs Rapperswil-Jona

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