Publication Date:
2017-03-21
Description:
The oxygen nonstoichiometry of SrFeO 3−δ was determined by solid-state Coulometric titration at 750°C-1040°C and 10 −18 ≤ p O 2 (atm)≤0.5. At T ≤850°C, a hysteresis in the oxygen nonstoichiometry (δ) isotherms indicates the presence of a two-phase region corresponding to a mixture of a perovskite and an oxygen vacancy ordered phase. The variation of δ with temperature at fixed p O 2 values and the variation of log( p O 2 ) with reciprocal temperature at fixed δ are reported. The p O 2 at the p - n transition in the electrical conductivity increases as the temperature increases, and the transition in the conductivity isotherm occurs at a composition of SrFeO 2.505(1) at 950°C and SrFeO 2.508(1) at 900°C. Since strontium exclusively occupies the A-site, a simple point defect model that assumes noninteracting defects can describe the isotherms but only at 1040°C; nonideal behavior is observed at lower temperatures. The partial molar thermodynamic quantities for oxygen in SrFeO 3−δ were determined.
Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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