Stability and oxygen-storage characteristics of Al-substituted YBaCo{sub 4}O{sub 7+{delta}}

• Published in: Journal of solid state chemistry Vol. 183; no. 3
• Main Authors: Raesaenen, Samuli, Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Motohashi, Teruki, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Yamauchi, Hisao, Karppinen, Maarit
• Format: Journal Article
• Language: English
• Published: United States 15.03.2010
• Subjects: ABSORPTION; ALKALINE EARTH METAL COMPOUNDS; ALUMINIUM COMPOUNDS; ANNEALING; BARIUM COMPOUNDS; CHALCOGENIDES; CHEMICAL ANALYSIS; CHEMICAL REACTIONS; COBALT COMPOUNDS; DECOMPOSITION; DESORPTION; ELEMENTS; FLUID FLOW; GAS FLOW; GRAVIMETRIC ANALYSIS; HEAT TREATMENTS; HEATING; MATERIALS SCIENCE; NONMETALS; OXIDES; OXYGEN; OXYGEN COMPOUNDS; QUANTITATIVE CHEMICAL ANALYSIS; SORPTION; STORAGE; TEMPERATURE RANGE; TEMPERATURE RANGE 0400-1000 K; THERMAL ANALYSIS; THERMAL GRAVIMETRIC ANALYSIS; TRANSITION ELEMENT COMPOUNDS; YTTRIUM COMPOUNDS
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2010.01.010

A series of Al-substituted YBa(Co{sub 1-x}Al{sub x}){sub 4}O{sub 7+{delta}} samples was synthesized and characterized with respect to the capability to store large amounts of oxygen at low temperatures (at 200-400 deg. C) and the phase decomposition upon heating under oxidizing conditions at higher temperatures (above 550 deg. C). It was revealed that increasing the Al-substitution level up to x{approx}0.10 boosts up the phase-decomposition temperature from {approx}550 to {approx}700 deg. C, while the unique oxygen absorption/desorption characteristics remain nearly the same as those of the pristine YBaCo{sub 4}O{sub 7+{delta}} phase. The maximum amount of excess oxygen absorbed by the Al-substituted YBa(Co{sub 1-x}Al{sub x}){sub 4}O{sub 7+{delta}} samples was determined to be as large as {delta}{approx}1.45 for x=0.10 (in 100 atm O{sub 2} at 320 deg. C). Isothermal annealing experiments carried out for the same x=0.10 phase at 300 deg. C revealed that it could be reversibly charged and discharged with 1.2 oxygen atoms per formula unit by switching the gas flow from N{sub 2} to O{sub 2} and vice versa. - Graphical abstract: A small amount of aluminum replacing cobalt in YBaCo{sub 4}O{sub 7+{delta}} works efficiently for boosting up the phase-decomposition temperature (T{sub D}), but yet retains the unique low-temperature oxygen-storage characteristics of the phase.