The influence on the spinel structure of Fe3+ Cr substitution was studied in flux-grown synthetic single crystals of the magnesiochromite– magnesioferrite (MgCr2O4–MgFe2O4) solid solution series. Samples were analysed by single-crystal X-ray diffraction, electron microprobe analyses, optical absorption and Mo¨ ssbauer spectroscopy. With the exception of iron-poor samples (3–12 mol-% MgFe2O4), optical absorption and Mo¨ ssbauer spectra show that iron occurs almost exclusively as trivalent Fe in the present samples. A very intense and broad absorption band at ca 7,800 cm1 dominates the optical absorption spectra of samples with higher Fe-contents. The appearance of this band is related to a distinct structural disorder of Fe3+ and a development of magnetic ordering as demonstrated by Mo¨ ssbauer spectra. Profound composition-related changes are observed in the Mo¨ ssbauer spectra, which are magnetically unsplit in the range 2–41 mol-% magnesioferrite, but become magnetically split in the range 59–100 mol-% magnesioferrite. Structural parameters a0 and M–O increase with magnesioferrite content and inversion degree, while u and T–O decrease. Our study confirms the previously reported (Lavina et al. 2002) influence of Fe3+ at the M site on T–O bond lengths in the spinel structure.

The MgCr2O4 - MgFe2O4 solid solution series: Effects of octahedrally coordinated Fe3+ on T-O bond lengths

LENAZ, DAVIDE;PRINCIVALLE, FRANCESCO;
2006-01-01

Abstract

The influence on the spinel structure of Fe3+ Cr substitution was studied in flux-grown synthetic single crystals of the magnesiochromite– magnesioferrite (MgCr2O4–MgFe2O4) solid solution series. Samples were analysed by single-crystal X-ray diffraction, electron microprobe analyses, optical absorption and Mo¨ ssbauer spectroscopy. With the exception of iron-poor samples (3–12 mol-% MgFe2O4), optical absorption and Mo¨ ssbauer spectra show that iron occurs almost exclusively as trivalent Fe in the present samples. A very intense and broad absorption band at ca 7,800 cm1 dominates the optical absorption spectra of samples with higher Fe-contents. The appearance of this band is related to a distinct structural disorder of Fe3+ and a development of magnetic ordering as demonstrated by Mo¨ ssbauer spectra. Profound composition-related changes are observed in the Mo¨ ssbauer spectra, which are magnetically unsplit in the range 2–41 mol-% magnesioferrite, but become magnetically split in the range 59–100 mol-% magnesioferrite. Structural parameters a0 and M–O increase with magnesioferrite content and inversion degree, while u and T–O decrease. Our study confirms the previously reported (Lavina et al. 2002) influence of Fe3+ at the M site on T–O bond lengths in the spinel structure.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/1854894
 Avviso

Registrazione in corso di verifica.
La registrazione di questo prodotto non è ancora stata validata in ArTS.

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 29
  • ???jsp.display-item.citation.isi??? 27
social impact