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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 25, Number 1
BKCSDE 25(1)
January 20, 2004 

Mossbauer Spectroscopic Study of La2-2xSr2xCu1-xFexO4-y (0 ≤ x ≤ 0
Jung Chul Park*, Song-Ho Byeon, Don Kim, Choong-Sub Lee
La2-2xSr2xCu1-xFexO4-y, Mossbauer spectroscopy, Electronic interaction
Tetragonal K2NiF4-type La2-2xSr2xCu1-xFexO4-y solid-solution have been synthesized by citrate based sol-gel method. The valence state of iron was determined by Mossbauer spectroscopy and subsequent iodometric titration clearly showed that the copper ions in this solid-solution are in the mixed valence state Cu(II/III). When x ≤ 0.3, Fe(III) is competing with the mixture of Cu(II) and Cu(III) and La2-2xSr2xCu1-xFexO4-y exhibits a metallic character. No evidence for Cu(II)-O-Fe(IV) ↔ Cu(III)-O-Fe(III) valence degeneracy was observed. In contrast, a small amount of Fe(IV) is observed with increasing x (x = 0.4 and 0.5), revealing a semiconducting behavior. These results suggest that the electronic interaction of Cu(III)-O-Fe(III) contributes greatly to the metallic character, while the electronic interaction of Cu(II)-O-Fe(IV) deteriorates the metallic character of La2-2xSr2xCu1-xFexO4-y.
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