Accession Number:

AD0613577

Title:

MOSSBAUER STUDIES ON IRON IN THE PEROVSKITES LA1-XSR-XFEO3 (0< OR = X< OR = 1). CONDITION FOR MAXIMUM RESONANCE ABSORPTION PEAK IN A SINGLELINE MOSSBAUER ABSORPTION,

Descriptive Note:

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR INSULATION RESEARCH

Personal Author(s):

Report Date:

1965-02-01

Pagination or Media Count:

49.0

Abstract:

Mossbauer spectra of the perovskite series La1-xSr-x FeO-y 0. 0 or x or 1.0 y Approx. 3 were obtained with Fe57 as the photon-emitting and absorbing nucleus and analyzed in detail. The Neel temperature of antiferromagnetic LaFeO3 decreases with increasing Sr concentration, in agreement with previous reports. That of antiferromagnetic SrFeO2.5 brownmillerite structure also decreases as oxygen is introduced to transform it to perovskite SrFeO3. Characteristic Fe4 lines, identified for compounds of high x, have isomer shifts between 0.10 and 0.20 mmsec relative to a source of Co57 in stainless steel Type 310. However, spectra of compounds of intermediate x indicate the existence of an intermediate Fe3 to 4 state, and a correlation between the total isomer shift of a compound and its Fe4 content was attempted. With increasing x a significant discontinuity in the total isomer shift, corresponding to a transition from magnetic order to disorder, was found. Line widths vary around 0.40 mmsec compared with 0.26 mmsec, the narrowest line obtainable in the present setup and show broadening in a sample fired for a short time. The temperature effect was used to calculate the specific heat. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE