2013 Fiscal Year Final Research Report

Effect of mechanical stress on defect equilibrium of nonstoichiometric oxides

Research Project

Project/Area Number	24656375
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Inorganic materials/Physical properties
Research Institution	Tohoku University
Principal Investigator	KAWADA Tatsuya 東北大学, 環境科学研究科, 教授 (10271983)
Project Period (FY)	2012-04-01 – 2014-03-31
Keywords	酸素不定比性 / 応力 / 欠陥平衡 / 酸素センサ / ペロブスカイト型酸化物
Research Abstract	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.

(4 results)