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KMID : 1059519930370110923
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Journal of the Korean Chemical Society
1993 Volume.37 No. 11 p.923 ~ p.928
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Study of Nonstoichiometric Composition and Physical Properties of Sr1+xHo1-xFeO4-y System
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Ryu Kwang-Sun
Ryu Kwang-Hyun
Rho Kwon-Sun
Yo Chul-Hyun
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Abstract
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The series of solid solutions in the Sr1+xHo1-xFeO4-y (x = 0.00, 0.25, 0.50, 0.75 and 1.00) systems with K2NiF4 type structure have been prepared at 1550℃ under an atmospheric air pressure. The X-ray powder diffraction spectra of these samples assign that the crystallographic phases are tetragonal system over the whole x range. The lattice volume was increased with increasing the substitution amount of the Sr2+ ion. The mole ratio of the Fe4+ ion to total iron ions or τ value has been determined by Mohr salt titration of the sample and then the y value was calculated from x and τ values. The τ and y values have been increased with x values. The nonstoichiometric chemical formula are formulated from the general formula of Sr1+xHo1-xFe1-τ3+Feτ4+O4-y replaced by x, τ and y values. Mossbauer spectra show the mixed valence state and coordination state of Fe3+ and Fe4+ ions. It is found out that the magnetic property of the samples is paramagnetic at room temperature. Electrical conductivity varied within the semiconductivity range of 1.0 to 1 × 10-9 Ω-1cm-1. Activation energy of the electrical conductivity was decreased with the τ value. The conduction mechanism should be explained by the hopping model of the conduction electrons between the valence states of Fe3+ and Fe4+ ions.
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KEYWORD
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