abstract
Magnetic particles were successfully synthesised by a new and simple one-step auto-ignition method, with octylamine as organic fuel and iron nitrate nonahydrate as an oxidant, both in an aqueous solution. After synthesis and stabilising at 550 degrees C in reduced atmosphere, the samples consisted of mostly well crystalline magnetite (Fe3O4), with a small amount of hematite present, in the form of micron-scale agglomerations of nanoparticles. A noticeable reduction of crystallite size of magnetite (42-28 nm) and an increase in the hematite crystallite sizes were observed with increasing octylamine addition, although the actual observed nanoparticle size increased slightly from similar to 30 up to 50 nm. The magnetic properties were assessed at room temperature, and all were found to be strongly ferrimagnetic with very narrow hysteresis loops. The saturation magnetisation at 4 T was 77.2-91.6 A m(2) kg(-1), and coercivity was only 10.03-11.30 kA m(-1) (126-142 Oe). These results are also compared to the few previous studies on using octylamine to produce magnetite nanoparticles, which were all purely organic hydrothermal processes, and produced materials with lower magnetisation values and comparable coercivity in similarly sized particles. (C) 2019 Elsevier B.V. All rights reserved.
keywords
COMBUSTION SYNTHESIS; NANOPARTICLES; PIGMENT; FE3O4
subject category
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
authors
Ben-Arfa, BAE; Mohseni, F; Salvado, IMM; Ferreira, JMF; Amaral, JS; Pullar, RC
our authors
Basam Abobaker Emhmed Ben-Arfa
Researcher
Farzin Mohseni
PhD Student
Isabel Margarida Miranda Salvado
Associate Professor
João Cunha de Sequeira Amaral
Assistant Researcher
José Maria da Fonte Ferreira
Retired Professor
Rob Pullar
CollaboratorGroups
G2 - Photonic, Electronic and Magnetic Materials
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
acknowledgements
R.C. Pullar wishes to thank FCT (Fundacao para a Ciencia e a Tecnologia, Portugal) Grant IF/00681/2015, and J.S. Amaral thanks FCT Grant IF/01089/2015, for supporting this work. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES.