Effect of mechanical stress on defect equilibrium of nonstoichiometric oxides

点击翻译按钮获取中文摘要

This research aimed at experimental quantification of the effect of mechanical stress on the defect equilibrium of oxide materials, (La,Sr)CoO3, (La,Sr)(Co,Fe)O3, (La,Sr)FeO3, La2NiO4, nd LaMnO3 were selected as the model materials. A YSZ ball was indented onto the sample surfaces and the potential between the electrodes placed on YSZ and on the sample were measured as a function of time. With the materials with oxygen deficient nonstoichiometry, the potential showed sudden decrease upon loading, and increased upon its release. During the load was kept constant, the potential decayed to the original value with a time constant equivalent to that of oxygen vacancy diffusion. The effect of the stress on the chemical potential was quantified from the emf shift. It was consistent with the thermodynamic calculation based on the chemical expansion coefficient of the corresponding materials.