Combined Neutron Diffraction and Atomistic Modeling Studies of Structure, Defects, and Water Incorporation in Doped Barium Cerate Perovskites
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- 作者：A. Kruth ; R. A. Davies ; M. S. Islam ; J. T. S. Irvine
- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：March 20, 2007
- 年：2007
- 卷：19
- 期：6
- 页码：1239 - 1248
- 全文大小：290K
- 年卷期：v.19,no.6(March 20, 2007)
- ISSN：1520-5002
文摘
A series of co-doped barium cerate perovskites, Ba1-xLaxCe0.9-xY0.1+xO2.95, with 0 
x 0.15, wasprepared by solid-state reaction, and the structural properties were investigated using high-resolutionneutron diffraction. All compositions were found to exhibit the orthorhombic Pbnm structure, althoughthe octahedral basal plane distortion is greatly reduced on doping, accompanied with an increase inoctahedral elongation. Compositions close to the solid solution limit, x = 0.1 and 0.15, are pseudo-tetragonal and pseudo-cubic and appear to be close to a phase transition, most likely to space groupsImma or I4/mcm. An anomaly in unit cell parameters occurs at low dopant concentration, 0.03 x 0.05, and was found to be reflected in reduction of the structural water uptake of the material within thiscompositional range. Atomistic simulations were carried out to study the energetics for dopant incorporationat A- and B-sites and water incorporation at oxygen sites. The results suggest that the reduced protonicdefect concentration within the compositional range where the structural anomaly occurs might be causedby less favorable water incorporation energies.
x 0.15, wasprepared by solid-state reaction, and the structural properties were investigated using high-resolutionneutron diffraction. All compositions were found to exhibit the orthorhombic Pbnm structure, althoughthe octahedral basal plane distortion is greatly reduced on doping, accompanied with an increase inoctahedral elongation. Compositions close to the solid solution limit, x = 0.1 and 0.15, are pseudo-tetragonal and pseudo-cubic and appear to be close to a phase transition, most likely to space groupsImma or I4/mcm. An anomaly in unit cell parameters occurs at low dopant concentration, 0.03 x 0.05, and was found to be reflected in reduction of the structural water uptake of the material within thiscompositional range. Atomistic simulations were carried out to study the energetics for dopant incorporationat A- and B-sites and water incorporation at oxygen sites. The results suggest that the reduced protonicdefect concentration within the compositional range where the structural anomaly occurs might be causedby less favorable water incorporation energies.