MAGNETIC SUSCEPTIBILITIES AND MOSSBAUER SPECTRA OF Sr2-xLaxFeO4-delta (0 less than or equal to x less than or equal to 0.5)

摘要

Solid solutions Sr2-xLaxFeO4-delta (0 less than or equal to x less than or equal to 0.5) with the K2NiF4-type structure have been prepared, and their magnetic susceptibilities have been measured at 4.2-300 K. Substitution of the La ion for the Sr site considerably weakens the antiferromagnetic transition of Sr2FeO4, and it finally disappears in Sr1.6La0.4FeO4-delta. Below the magnetic transition temperatures, magnetic susceptibilities measured under zero-field cooled and field cooled conditions indicate the formation of a spin-glass state. Mossbauer spectra for Sr1.9La0.1FeO4-delta at RT and at 9 K have been measured, and the spectra at 9 K show the presence of magnetic hyperfine interaction of Fe4+ ions; there is no charge disproportionation of Fe4+ yields Fe3+ + Fe5+, even below the magnetic transition temperature. 12 refs.