Electronic behavior of three oxygen non-stoichiometric Fe{sup 4+}/Fe{sup 3+} oxoperovskites

Journal Article · Thu Dec 15 00:00:00 EST 2005 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2005.09.020· OSTI ID:20784814

Zhou, H D ^[1]; Goodenough, J B ^[1]

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1. Texas Materials Institute, ETC 9.102, 1 University Station, C2201, University of Texas at Austin, Austin, Texas 78712-1063 (United States)

For comparison with the Mn{sup 4+}/Mn{sup 3+} oxoperovskites at the crossover from localized to itinerant behavior of the {sigma}-bonding e electrons, the electronic properties of three oxygen non-stoichiometric, mixed-valent Fe{sup 4+}/Fe{sup 3+} oxoperovskites were explored by measuring their resistivity {rho}(T), thermoelectric power {alpha}(T), and magnetic susceptibility {chi}(T). Oxidation of Ca{sub 2}Fe{sub 2}O{sub 5} by annealing in ozone progresses by oxygen insertion to give conductive CaFeO{sub 3} perovskite clusters in a localized-electron, weakly oxidized brownmillerite Ca{sub 2}Fe{sub 2}O{sub 5+} {sub {delta}} matrix. Removal of 0.12 oxygen per formula unit from La{sub 1/3}Sr{sub 2/3}FeO{sub 3} lowers somewhat its cooperative disproportionation reaction, and fivefold-coordinated ions neighboring oxygen vacancies in the more ionically bonded slabs act as donors to the covalently bonded Fe(V)O{sub 6} planes. Single-crystal SrFeO{sub 2.83} exhibited bad-metal behavior with superparamagnetic, electron-rich fluctuations below 240 K that, on cooling below 190 K, become progressively trapped by the oxide-ion vacancies as an immobile second phase; long-range antiferromagnetic order is stabilized below a T {sub N}{approx}60 K.

• OSTI ID: 20784814
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 12 Vol. 178; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANNEALING
ANTIFERROMAGNETISM
CALCIUM COMPOUNDS
FLUCTUATIONS
IRON IONS
MONOCRYSTALS
OXIDES
PEROVSKITE
SUPERPARAMAGNETISM
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K