Oxygen sensing element having barrier layer between ceramic substrate and solid electrolyte layer

摘要

An oxygen sensing element having a ceramic substrate, a layer of an oxygen ion conductive solid electrolyte such as zirconia containing a stabilizing oxide such as yttria, and a pair of electrode layers formed on one side of the solid electrolyte layer so as to be spaced from each other. To prevent a significant change in the output characteristic of the element caused by diffusion of the stabilizing oxide from the solid electrolyte layer into the ceramic substrate, there is a barrier layer which intervenes between the substrate and the solid electrolyte layer at least in a region between the two electrode layers. The barrier layer is formed of a ceramic material such as the above mentioned solid electrolyte or a metal such as platinum, or has a double-layer structure consisting of a metal layer in direct contact with the substrate and an outer layer formed of a ceramic material.