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Journal of Materials Science

, Volume 29, Issue 3, pp 762–767 | Cite as

Mössbauer spectral invetigations of ultrafine rare-earth iron garnets

  • V. K. Sankaranarayanan
  • N. S. Gajbhiye
Papers

Abstract

Ultrafine rare-earth iron garnets (RIG) in the crystalline size range 1.0–35 nm, prepared by the citrate precursor method have been investigated by Mössbauer spectroscopy at room temperature. The crystallites of 10–35 nm size show two six-line spectra corresponding to tetrahedral and octahedral Fe3+ with isomer shifts, δ, and magnetic hyperfine fields, Hhf, comparable to the bulk polycrystalline garnets. However, 1.0–1.5 nm crystallites (X-ray amorphous) show a quadrupole split doublet due to superparamagnetic nature with isomer shifts (0.3 mms−1) internediate between tetrahedral and octahedral values of bulk garnets. The relative increase of tetrahedral δ and the decrease in the octahedral δ indicate, respectively, an increase of tetrahedral Fe-O bond distance and a decrease of octahedral Fe-O bond distance in the ultrafine state, in complete agreement with the observations made earlier in the spectrochemical investigations. The lines are broad (linewidth=0.65 mms−1) and the quadrupole splittings are relatively larger (ΔEQ = 1.0 mms−1) indicating large deviation from cubic symmetry at the Fe3+ sites.

Keywords

Isomer Shift Quadrupole Split Hyperfine Field Magnetic Hyperfine Field Magnetic Hyperfine 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • V. K. Sankaranarayanan
    • 1
  • N. S. Gajbhiye
    • 1
  1. 1.Department of chemistryIndian Institute of TechnologyKanpurIndia

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