Synthesis, morphology, thermal stability and magnetic properties of α″-Fe16N2 nanoparticles obtained by hydrogen reduction of γ-Fe2O3 and subsequent nitrogenation
| Autor: | I. Dirba, Philipp Komissinskiy, Leopoldo Molina-Luna, Hans-Joachim Kleebe, C. A. Schwöbel, Michael Duerrschnabel, L.V.B. Diop, Kathrin Hofmann, Oliver Gutfleisch |
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| Přispěvatelé: | Technische Universität Darmstadt (TU Darmstadt) |
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Polymers and Plastics Hydrogen Nanoparticle chemistry.chemical_element 02 engineering and technology 7. Clean energy 01 natural sciences Ammonia chemistry.chemical_compound Nuclear magnetic resonance 0103 physical sciences Thermal stability [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] Chemical composition ComputingMilieux_MISCELLANEOUS 010302 applied physics [PHYS]Physics [physics] Metals and Alloys [CHIM.MATE]Chemical Sciences/Material chemistry 021001 nanoscience & nanotechnology Microstructure Electronic Optical and Magnetic Materials Chemical engineering chemistry Ceramics and Composites [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] Particle Particle size 0210 nano-technology |
| Zdroj: | Acta Materialia Acta Materialia, Elsevier, 2017, 123, pp.214-222. ⟨10.1016/j.actamat.2016.10.061⟩ |
| ISSN: | 1359-6454 |
| DOI: | 10.1016/j.actamat.2016.10.061⟩ |
| Popis: | Typical synthesis of α″-Fe16N2 nanoparticles involves reduction of iron oxides by hydrogen at elevated temperatures which is disadvantageous due to the particle coalescence. Here we report on a process for reduction of iron oxides at elevated pressures and show that by increasing hydrogen pressure from atmospheric to 53 MPa, it is possible to reduce the reaction temperature from 663 K down to 483 K, resulting in phase-pure α-Fe nanoparticles without noticeable particle growth. By subsequent nitrogenation in an ammonia flow, fine, 99% phase-pure α″-Fe16N2 nanoparticles could be synthesized. The reduction temperature and the respective particle size has a significant influence on the nitrogenation step. α″-Fe16N2 nanoparticles exhibit semi-hard magnetic properties with Ms(0) = 215 Am2 kg−1, μ0Hc = 0.22 T, TC = 634 K and exchange stiffness Ac = 6.84 pJ m−1, Aa,b = 7.53 pJ m−1. Synthesis conditions, microstructure, chemical composition and thermal stability of the nanoparticles are systematically studied and correlated with the observed magnetic properties. |
| Databáze: | OpenAIRE |
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