Formation of Fe-Fe Antiferromagnetic Dimers in Doped TiO 2 :Fe Nanoparticles
| Autor: | Yermakov, A. Y., Gubkin, A. F., Korolev, A. V., Molochnikov, L. S., Uimin, M. A., Rosenfeld, E. V., Kurkin, M. I., Minin, A. S., Volegov, A. S., Boukhvalov, D. W., Konev, S. F. |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
MAGNETIC RESONANCE MEASUREMENT
ANTIFERROMAGNETIC CORRELATIONS QUANTUM MECHANICAL MODEL BINARY ALLOYS TITANIUM DIOXIDE TIO2 NANO-PARTICLES NANOSTRUCTURED MATERIALS THEORETICAL STUDY PARAMAGNETIC RESONANCE MAGNETIC CLUSTER MAGNETIC PROPERTIES PARAMAGNETISM ANTIFERROMAGNETICS OXYGEN CRYSTAL STRUCTURE EXCHANGE INTERACTIONS MIXED MAGNETIC STATE ANTIFERROMAGNETISM ANATASE STRUCTURES MAGNETIC MOMENTS OXYGEN VACANCIES NANOMAGNETICS NANOPARTICLES DENSITY FUNCTIONAL THEORY |
| Zdroj: | Journal of Physical Chemistry C |
| Popis: | In this work, we report the results of comprehensive experimental and theoretical study of magnetic properties of TiO 2 nanoparticles (20 nm) doped with Fe at various concentrations ranging from 0.1 to 4.6 at. %. Our electron paramagnetic resonance and magnetic measurements data evidence the mixed magnetic state, where paramagnetic Fe 3+ ions coexist with short-range antiferromagnetic correlations caused by negative exchange interaction between neighboring Fe 3+ ions. A quantum mechanical model of the Fe-based magnetic cluster represented as a set of dimers with strong a(100-300) K and weak (a1 K) exchange interactions has been proposed. Our model was found to provide a good description of magnetic properties of TiO 2 :Fe nanopowders. Density-functional theory (DFT) calculations revealed Fe 3+ oxidation state of the iron center in the vicinity of an oxygen vacancy in the crystal structure of anatase. DFT calculations confirmed that two types of Fe 3+ spin-pairs with weak and strong exchange interactions can be formed in the vicinity of an oxygen vacancy. Accumulation of magnetic moment carriers and formation of magnetic clusters in TiO 2 nanoparticles with anatase structure were found to be a general tendency for all studied TiO 2 :Fe nanopowders. © Copyright 2018 American Chemical Society. The research was supported by the Russian Science Foundation (project 16-12-10004). The authors are grateful for the contributions made by our colleagues G. S. Zakharova, A. S. Konev, K. I. Borodin, Z. A. Phatakhova, A. M. Murzakaev, and V. S. Gaviko. The X-ray investigation and magnetic measurements have been performed in the Collaborative Access Center of M. N. Mikheev Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia. |
| Databáze: | OpenAIRE |
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