Structural and electrical characterisation of SrCe_1-xY_xO_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 diffraction and AC impedance spectroscopy, and the effect of the yttrium dopant concentration on structure and electrical properties has been investigated. X-ray diffraction studies show a decrease in lattice volume with increasing yttrium content.

Electrical conductivity studies have been made as a function of oxygen partial pressure, and at a partial pressure of water vapour of 0.007 atm. The total conductivity has been separated into different components by fitting procedures and regions of ionic and p-type conduction have been identified. At 800 degrees C and at the water vapour partial pressure of 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 regarded as protonic rather than n-type, decreased with doping, while the p-type component at high oxygen partial pressure increased. The relationship between the effect of doping on the conductivity and unit cell volume is discussed, (C) 1999 Elsevier Science B.V.

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