Insights on thermal and transport features of BaCe0.8-xZrxY0.2O3-delta proton-conducting materials

Abstract

BaCe0.8-xZrxY0.2O3-delta-based materials (BCZYx, 0 <= x <= 0.8) are obtained through a modified citrate-nitrate combustion method at 1150 degrees C with following sintering at 1450 degrees C. Then their thermomechanical and electrical properties are thoroughly investigated. Using of wet-chemical route it is allowed to obtain single-phase and dense ceramic samples at a wide range of Ce:Zr ratio. It is found that the relative linear expansion of ceramics decreased with gradual increasing x, which is reflected in a corresponding drop of thermal expansion coefficient (TEC) values, from 11.6 x 10(-6) to 83 x 10(-6) K-1 (similar to 30%). It is also found that, the decrease in pO(2) does not significantly change the ceramics' linear expansion, whereas the increase in pH(2)O resulted in marked variation of both linear expansion and TEC values. The electrical conductivity of BCZYx decreases from 0.85 to 0.02 mS cm(-1) at 300 degrees C (similar to 98%) and from 69.9 to 17.9 mS cm(-1) at 900 degrees C (similar to 75%) with the increase of x. At the same time, hole contribution on total conductivity increases with increasing x. Taking into account the phase stability in BaCe0.8-xZrxY0.2O3-delta system, the material with optimal properties should be sought at close concentration of Ce and Zr. (C) 2014 Elsevier B.V. All rights reserved.