Abstract
The kinetics of point-defect association/dissociation reactions in Ce 0.8Cd0.2O1.9 and their influence on the crystal lattice parameter are investigated by monitoring thermally induced stress and strain in substrate and self-supported thin films. It is found that, in the temperature range of 100-180 °C, the lattice parameter of the substrate-supported films and the lateral dimensions of annealed, self-supported films both exhibit a hysteretic behavior consistent with dissociation/ association of oxygen vacancy-aliovalent dopant complexes. This leads to strong deviation from linear elastic behavior, denoted in the authors' previous work as the "chemical strain" effect. At room temperature, the equilibrium state of the point defects is reached within a few months. During this period, the lattice parameter of the substrate-supported films spontaneously increases, while the self-supported films are observed to transform from the flat to the buckled state, indicating that formation of the dopant-vacancy complex is associated with a volume increase. The unexpectedly slow kinetics of establishing the defect equilibrium at room temperature can explain the fact that, depending on the sample history, the "observable" lattice parameters of Ce0.8Cd0.2O1.9, as reported in the literature, may differ from one another by a few tenths of a percent. These findings strongly suggest that the lattice parameter of the materials with a large concentration of interacting point defects is a strong function of time and material preparation route.
Original language | English |
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Pages (from-to) | 634-641 |
Number of pages | 8 |
Journal | Advanced Functional Materials |
Volume | 19 |
Issue number | 4 |
DOIs | |
Publication status | Published - 24 Feb 2009 |
Funding
Nancy and Stephen Grand Research Center; Wiley InterScienceThis research is made possible in part by the historic generosity of the Harold Perlman Family and was partially supported by the Nancy and Stephen Grand Research Center for Sensors and Security. The authors express their appreciation to Dr. Rotraut Merkle of the MPI for Solid State Research, Stuttgart, fora very fruitful discussion. Supporting Information is available online from Wiley InterScience or from the author.
All Science Journal Classification (ASJC) codes
- General Chemistry
- Condensed Matter Physics
- General Materials Science