A Novel Oxygen Sensor Based on a Metal–Metal Oxide Scale System

Abstract

A novel oxygen sensor was proposed. The sensor, an electrochemical cell, was composed of a metal as reference electrode, its oxide scale as electrolyte and Pt or other adequate materials as sample electrode. It is expected that the electrolyte is self-restorative because it can be restored by high temperature oxidation. The emf measurements were carried out at 873 K in cells using zirconium. At ${\text{P}}_{{\text{O}}_{\text{2}} } = 1 \sim 10^{ - 3}$ atm, the emf vs. ${\text{log P}}_{{\text{O}}_{\text{2}} }$ plot lies on a straight line and its gradient is 2.303RT/4F, suggesting t _ion=1 at the surface of the scale. The emf steeply decreases with decreasing ${\text{P}}_{{\text{O}}_{\text{2}} }$ at ${\text{P}}_{{\text{O}}_{\text{2}} } < 10^{ - 3}$ atm which can not be explained by the increase in the electronic conductivity and is explained by a gas laminar film phase at the surface of the sample electrode.