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gamma-Fe2O3 Nanopowders Synthesized in Microwave Plasma and Extraordinarily Strong Temperature Influence on Their Mossbauer Spectra

Basic information
Original title:gamma-Fe2O3 Nanopowders Synthesized in Microwave Plasma and Extraordinarily Strong Temperature Influence on Their Mossbauer Spectra
Authors:Bohumil David, Nadežda Pizurova, Oldřich Schneeweiss, Eva Santava, Vít Kudrle, Ondřej Jašek
Further information
Citation:DAVID, Bohumil, Nadežda PIZUROVA, Oldřich SCHNEEWEISS, Eva SANTAVA, Vít KUDRLE a Ondřej JAŠEK. gamma-Fe2O3 Nanopowders Synthesized in Microwave Plasma and Extraordinarily Strong Temperature Influence on Their Mossbauer Spectra. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, VALENCIA: AMER SCIENTIFIC PUBLISHERS, 2012, roč. 12, č. 12, s. 9277-9285. ISSN 1533-4880. doi:10.1166/jnn.2012.6767.Export BibTeX
@article{1093154,
author = {David, Bohumil and Pizurova, Nadežda and Schneeweiss, Oldřich and Santava, Eva and Kudrle, Vít and Jašek, Ondřej},
article_location = {VALENCIA},
article_number = {12},
doi = {http://dx.doi.org/10.1166/jnn.2012.6767},
keywords = {Microwave Plasma; Nanopowder; gamma-Fe2O3; Mossbauer Spectroscopy; Lamb-Mossbauer Factor},
language = {eng},
issn = {1533-4880},
journal = {JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY},
title = {gamma-Fe2O3 Nanopowders Synthesized in Microwave Plasma and Extraordinarily Strong Temperature Influence on Their Mossbauer Spectra},
url = {http://dx.doi.org/10.1166/jnn.2012.6767},
volume = {12},
year = {2012}
}
Original language:English
Field:Plasma physics
WWW:link to a new windowweb publikace
Type:Article in Periodical
Keywords:Microwave Plasma; Nanopowder; gamma-Fe2O3; Mossbauer Spectroscopy; Lamb-Mossbauer Factor

The article reports on two nanopowders synthesized in microwave plasma: the first sample was synthesized in a torch discharge at 1 bar and the second sample was synthesized in low-pressure plasma at 40 mbar. Morphology, composition and properties of the powders were studied by TEM, XRD, Raman and Mossbauer spectroscopies, and magnetic measurements. In the XRD patterns of the samples only gamma-Fe2O3 was identified (mean crystallite size d(XRD) was 24 nm for the first sample and 13 nm for the second sample). Based on the Mossbauer spectra measured at 5 K, the presence of other iron oxide phases was excluded in both samples. Unusually strong temperature dependence of the Lamb-Mossbauer factor was observed: I-SA(5 K)//(SA)(293 K) = 6 in the case of the first sample and I-SA(5 K)//(SA)(293 K) = 22 for the second sample (I-SA denotes integral spectrum area). This effect is explained as the consequence of the reduced agglomeration of electrically charged nanoparticles in the plasma, i.e., particles can either move at 293 K (when they are free) or tilt (if they are a part of a chain). Superparamagnetic phase was not observed in the room-temperature Mossbauer spectra of both samples.

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