ORCID Profile
0000-0003-2081-7475
Current Organisations
Warsaw University of Technology
,
Instytute of Power Engineering - Research Institute
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Publisher: Elsevier BV
Date: 26-07-2010
Publisher: Elsevier BV
Date: 10-2002
Publisher: Elsevier BV
Date: 2003
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C1DT11212K
Abstract: Mössbauer spectroscopy and magnetization studies of YBaCo(4-x)Fe(x)O(7+δ) (x = 0-0.8) oxidized at 0.21 and 100 atm O(2), indicate an increasing role of penta-coordinated Co(3+) states when the oxygen content approaches 8-8.5 atoms per formula unit. Strong magnetic correlations are observed in YBaCo(4-x)Fe(x)O(8.5) from 2 K up to 55-70 K, whilst the average magnetic moment of Co(3+) is lower than that for δ ≤ 0.2, in correlation with the lower (57)Fe(3+) isomer shifts determined from Mössbauer spectra. The hypothesis on dominant five-fold coordination of cobalt cations was validated by molecular dynamics modeling of YBaCo(4)O(8.5). The iron solubility limit in YBaCo(4-x)Fe(x)O(7+δ) corresponds to approximately x ≈ 0.7. The oxygen intercalation processes in YBaCo(4)O(7+δ) at 470-700 K, analyzed by X-ray diffraction, thermogravimetry and controlled-atmosphere dilatometry, lead to unusual volume expansion opposing to the cobalt cation radius variations. This behavior is associated with increasing cobalt coordination numbers and with rising local distortions and disorder in the crystal lattice on oxidation, predicted by the computer simulations. When the oxygen partial pressure increases from 4 × 10(-5) to 1 atm, the linear strain in YBaCo(4)O(7+δ) ceramics at 598 K is as high as 0.33%.
Publisher: American Chemical Society (ACS)
Date: 21-03-2007
DOI: 10.1021/CM070096X
Location: Belarus
No related grants have been discovered for Yevgeniy Naumovich.