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A Raman scattering study of structural changes in LaMn1-xCoxO3+δ system

Title
A Raman scattering study of structural changes in LaMn1-xCoxO3+δ system
Authors
Minh N.V.Yang I.-S.
Ewha Authors
양인상
SCOPUS Author ID
양인상scopus
Issue Date
2006
Journal Title
Vibrational Spectroscopy
ISSN
0924-2031JCR Link
Citation
vol. 42, no. 2, pp. 353 - 356
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
We present results of Raman scattering studies on LaMn1-xCoxO3+δ over a wide range of doping content (x = 0.1-0.75) and temperature range of 20-300 K. Powder X-ray diffraction patterns show that there is a structural change from orthorhombic to rhombohedral at x = 0.5 as x increases. Raman spectra of all LaMn1-xCoxO3+δ samples show peaks near 260, 500, and 650 cm-1. However, the Raman spectra are not drastically different from each other across the structural phase transition at x = 0.5. On the other hand, the peak frequencies of the modes near 260 and 500 cm-1 as functions of Co content (x) show slope changes at x = 0.5. The full-width at the half-maximum (FWHM) of the mode near 650 cm-1 as a function of Co content (x) shows minimum at x = 0.5. Normally, larger values of FWHM are expected at near x = 0.5, if the mode were affected by the structural disorder at the phase boundary. Therefore, it is likely due to lowest charge concentration at x = 0.5, which results in lowest screening effect. This is consistent with the fact that the intensity of the phonons is strongest at x = 0.5. As the temperature decreases, the two peaks near 500 and 650 cm-1 of different Co contents, related with octahedral distortions, are found to shift to lower frequencies unlike the usual temperature behavior. However, no abrupt change in the peak frequencies and the FWHM is observed across measured temperature range, regardless of the Co content. © 2006 Elsevier B.V. All rights reserved.
DOI
10.1016/j.vibspec.2006.05.027
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자연과학대학 > 물리학전공 > Journal papers
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