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KMID : 1059519910350020099
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Journal of the Korean Chemical Society
1991 Volume.35 No. 2 p.99 ~ p.104
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A Study on Nonstoichiometry and Physical Properties of the Mixed Valency Sr1+xEr1-xFeO4-y Ferrite System
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Yo Chul-Hyun
Ryu Kwang-Sun
Pyun Mu-Sil
Lee Sung-Joo
Choi Joong-Gill
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Abstract
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Nonstoichiometric solid solutions of Sr1+xEr1-xFeO4-y system (x = 0.00, 0.25, 0.50, 0.75 and 1.00) with layered K2NiF4 type structure were prepared at 1350℃ under atmospheric pressure. By the analysis of X-ray diffraction, the crystallographic structures of the solid solution of all compositions were found to be pseudo-tetragonal system. Nonstoichiometric chemical formulas have been determined by Mohr salt analysis. It shows that the amount of Fe4+ increases with increasing x up to 0.50 and then decreases, and the value of oxygen nonstoichiometry increases with increasing x value. Mixed valency states of Fe3+ and Fe4+ in the sample were identified again by Mossbauer spectroscopic analysis at 298 K. Electrical conductivity varied within the semiconductivity range of 10-2 ∼ 10-7(Ω-1cm-1), activation energy for electrical conduction decreased with the increment of the mole ratio of Fe4+ or τ value. The conduction mechanism could be explained by the hopping model of the conduction electrons between the valency states of Fe3+ and Fe4+.
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KEYWORD
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