Structural and electrical characterisation of SrCe1-xYxO xi

The acceptor-doped perovskite proton conductor SrCe1-xYxOxi (x = 0.025 to 0 .20, xi = 3 - x/2) has been prepared and characterised using X-ray diffract ion and AC impedance spectroscopy, and the effect of the yttrium dopant con centration on structure and electrical properties has been investigated. X- ray diffraction studies show a decrease in lattice volume with increasing y ttrium content. Electrical conductivity studies have been made as a functio n of oxygen partial pressure, and at a partial pressure of water vapour of 0.007 atm. The total conductivity has been separated into different compone nts by fitting procedures and regions of ionic and p-type conduction have b een identified. At 800 degrees C and at the water vapour partial pressure o f 0.007 atm, the ionic conductivity showed a maximum at a doping level of x = 0.10, reaching a value of 5 mS/cm. The conductivity component appearing at low oxygen partial pressure, which according to recent studies may be re garded as protonic rather than n-type, decreased with doping, while the p-t ype component at high oxygen partial pressure increased. The relationship b etween the effect of doping on the conductivity and unit cell volume is dis cussed, (C) 1999 Elsevier Science B.V. All rights reserved.