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Temperature‐dependent Raman scattering study of Fe 3 O 2 BO 3 ludwigite
Author(s) -
Leite C. A. F.,
Guimarães R. B.,
Fernandes J. C.,
Continentino M. A.,
Paschoal C. W. A.,
Ayala A. P.,
Guedes I.
Publication year - 2002
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.801
Subject(s) - raman spectroscopy , orthorhombic crystal system , raman scattering , delocalized electron , atmospheric temperature range , phonon , chemistry , ion , analytical chemistry (journal) , x ray raman scattering , crystallography , crystal structure , condensed matter physics , optics , physics , organic chemistry , chromatography , meteorology
Raman scattering measurements were carried out for Fe 3 O 2 BO 3 and Ni 2 FeO 2 BO 3 ludwigite crystals in the temperature range from 15 to 300 K. At room temperature ludwigite has an orthorhombic structure belonging to space group $D_{2h}^{9}$ . Attempts made to record polarized Raman spectra were successful, and we were able to identify most of the phonons belonging to A 1 g species. A careful analysis of the spectra shows that the observed Raman modes do not exhibit variations either in wavenumber or intensity or both with temperature, indicating that the $D_{2h}^{9}$ phase does not undergo any structural modification in the temperature range investigated. Also, we observed for Fe 3 O 2 BO 3 ludwigite the appearance of a continuous scattering background in the phonon spectrum for temperatures below 200 K . This background, which is due to electronic transitions between Fe 2+ and Fe 3+ ions, is related to the charge delocalization effect. Copyright © 2002 John Wiley & Sons, Ltd.
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