Trends in the development of solid state amperometric and potentiometric high temperature sensors

High temperature sensors based on solid electrolytes are well established i n many applications. In this context. stabilized zirconia as an oxygen ion conductor plays the key role to monitor oxygen. Recent trends in the use of stabilized zirconia aim at the detection of other exhaust or environmental gases like NOx, CO or hydrocarbons. This is possible by, e.g. monitoring c urrents of specific electrode reactions at a given voltage ('amperometric d evices') or monitoring voltages between different electrodes which result f rom specific electrode reactions including the kinetically determined forma tion of surface oxygen during different catalytic reactions ['mixed-potenti al (non-Nernstian) devices']. In all applications, the catalytic and electr ochemical properties of the electrode materials play a key role for achievi ng reproducible sensor signals. This requires controlled microstructures do wn to the atomic scale. Therefore, extensive work now focuses on the struct ural as well as functional optimization of known, and on the development of new electrode materials. In this promising trend particular emphasis is pu t on the in-situ spectroscopic and microscopic characterization of the vari ous interfaces under sensor operation conditions. (C) 2000 Elsevier Science B.V. All rights reserved.