A Variable Temperature X- and W-Band EPR Study of Fe-Doped SiCN Ceramics Annealed at 1000, 1100, and 1285 °C: Dangling Bonds, Ferromagnetism and Superparamagnetism
- Autores: Andronenko S.1, Rodionov A.1, Misra S.2
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Afiliações:
- Institute of Physics, Kazan Federal University
- Department of Physics, Concordia University
- Edição: Volume 49, Nº 4 (2018)
- Páginas: 335-344
- Seção: Original Paper
- URL: https://journals.rcsi.science/0937-9347/article/view/248048
- DOI: https://doi.org/10.1007/s00723-017-0973-y
- ID: 248048
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Resumo
Polymer-derived SiCN ceramics, annealed (also referred to as pyrolyzed) at 1000, 1100, and 1285 °C, and doped with Fe(III) acetylacetonate, are investigated by electron paramagnetic resonance (EPR) from 4 to 120 K at X-band (9.425 GHz). In addition, the SiCN ceramic, annealed at 1100 °C, was studied by EPR at 300 K at W-band (93.96 GHz). There was observed a significant increase in EPR linewidth due to dangling bonds (g = 2.001) below 20 K at X-band. The low-field X-band FMR line (g ≈ 12) indicated the presence of ferromagnetic Fe5Si3 crystallites. There were found two EPR lines due to carbon-related dangling bonds: (1) those present as defects on the surface of the free-carbon phase (as sp2 carbon-related dangling bonds with g = 2.0011) and (2) those present within the bulk of carbon phase (as sp3 carbon-related dangling bonds with g = 2.0033). On the other hand, the intense low-field EPR signal observed at X-band was not observed at W-band. As well, there was observed splitting of the single broad EPR signal observed at g = 2.05 at X-band into two signals at W-band at g = 1.99 and g = 2.06, due to two different Fe-containing superparamagnetic nanocrystallites. Two new EPR signals, not observed at X-band, were observed at W-band, namely at g = 2.28 and g = 3.00, which are also due to g∥ of these superparamagnetic nanocrystallites.
Sobre autores
S. Andronenko
Institute of Physics, Kazan Federal University
Autor responsável pela correspondência
Email: sergey.andronenko@gmail.com
ORCID ID: 0000-0002-3424-923X
Rússia, Ul. Kremlevskaya, 18, Kazan, 420008
A. Rodionov
Institute of Physics, Kazan Federal University
Email: sergey.andronenko@gmail.com
Rússia, Ul. Kremlevskaya, 18, Kazan, 420008
S. Misra
Department of Physics, Concordia University
Email: sergey.andronenko@gmail.com
Canadá, 1455 de Maisonneuve Boulevard West, Montreal, QC, H3G 1M8