An investigation of the characteristics of oxygen sensors using a Nd1+xBa2−xCu3Oy-based ceramics rod.

A hot spot, which is a glowing orange local area, appears in RE Ba 2 Cu 3 O y (RE : rare earth) ceramic rods when a voltage exceeding a certain value is applied at room temperature. After a hot spot appears, the current changes according to the partial pressure of oxygen in the ambient atmosphere, acting as an oxygen sensor without the need for a heating system. In this study, the moisture resistance and oxygen-sensing characteristics of 5 mol% Nd 2 BaCuO 5 -added Nd 1+ x Ba 2− x Cu 3 O y (x = 0–0.8) rods were investigated by preparing ceramic rods via a solid-state reaction at 960 °C. The moisture resistance improved at x ≥ 0.4. In the case of x ≤ 0.4, the current increased as the voltage increased, reached its peak value, and subsequently decreased. Finally, the current increased monotonically with increasing voltage at x ≥ 0.6. Furthermore, the sensitivity to gas was not strongly affected by the changes in x. The characteristics are discussed from the viewpoint of the heat balance in the rod and lattice defects of the material. [ABSTRACT FROM AUTHOR]