Oxygen partial pressure measuring device - has permeable sintered body sepg. reference space providing three=phase contact

The space holding O2-contg. reference gas and an internal contact in appts. for the high temp. measurement of O2 partial pressures is sepd. from the space containing the test medium by a wall of solid electrolyte permeable to O2 ions. The reference gas space provides three-phase contact between this solid electrolyte, the internal contact and the reference gas, and is at least partially filled by a sintered body, also permeable to O2 ions, in contact with the internal contact and the solid electrolyte. The reference gas space may be a tube of the solid electrolyte, or a metal or ceramic tube contg. a disc of the electrolyte. A thermo-element is pref. located in the sintered body. Oxygen partial pressures are measured e.g. in molten material or gases. The contact is superior to known contacts made from Pt paints or by evapn. of Pt cpds. on hot supports.