Investigation on Oxygen Resistance Properties of RBaCo_2O_(5+δ) Ceramics

RBaCo 2 O 5+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℃. 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 RBaCo 2 O 5+δ samples with the change of atmosphere at constant temperatures are studied. The results show that RBaCo 2 O 5+δ could be potential oxygen resistance sensor materials, and that the responding rates of RBaCo 2 O 5+δ are YBaCo 2 O 5+δ DyBaCo 2 O 5+δ GdBaCo 2 O 5+δ PrBaCo 2 O 5+δ NdBaCo 2 O 5+δ SmBaCo 2 O 5+δ EuBaCo 2 O 5+δ . For YBaCo 2 O 5+δ , the resistivity rises quickly due to the oxygen desorption when the atmosphere is switched from oxygen to nitrogen at 700℃, 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.