Synthesis and magnetic properties of flower-like FeCo particles through a one pot polyol process Prakash Karipoth, Arun Thirumurugan, R. Justin Joseyphus ⇑ Magnetic Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli 620 015, India article info Article history: Received 5 March 2013 Accepted 24 April 2013 Available online xxxx Keywords: FeCo Polyol process Binary alloys Thermomagnetic analysis Shape anisotropy Ethylene glycol Curie temperature Solid solution Flower-like Phase transformation abstract FeCo alloys of various compositions with flower-like morphology were synthesized using a unique one pot polyol process. The morphology of Fe particles was cubic, whereas the FeCo particles showed flower-like morphology, with more petals for the Co rich FeCo. The average particle size varied from 120 to 155 nm depending on the composition of the alloy. The Curie temperature as determined by ther- momagnetic analysis was 985 °C for Fe 67 Co 33 and 939 °C for the Fe 36 Co 64 samples. Their corresponding bcc to fcc phase transformation temperatures were 985 and 825 °C, respectively. Coercivity up to 511 Oe was observed due to the shape anisotropy arising out of the flower-like morphology compared to the usual cubic or spherical morphologies. Post-annealing studies showed that Fe 67 Co 33 is more stable compared to other compositions. Ó 2013 Elsevier Inc. All rights reserved. 1. Introduction FeCo alloys are used in variety of applications such as targeted drug delivery, cancer therapy [1,2], high-frequency power applica- tions [3], magnetic-resonance imaging [4], electromagnetic EM-wave absorption [5,6], and magnetoelastic soft actuators [7]. The synthesis of FeCo through chemical synthesis techniques has been a subject of interest and attempted through sol–gel method [8], hydrogen reduction (CSM-HR) [9], thermal decomposition [10,11], thermolysis [12,13], borohydride reduction [14], co-pre- cipitation [15], and alkalide reduction [16]. However, most of these methods have limitations like prolonged synthesis duration [15,17], use of environmentally hazardous chemicals [18], undesir- able oxide formation in the final product [19], complex synthesis setups [20], and too many reaction dependent parameters [9]. As compared to these synthesis methods, polyol process is a simple, eco-friendly, and cost effective route to synthesize metal and alloy particles [21–23]. Polyols act as reducing agent and also overcome the problem of oxidation of metal particles in solution compared to other chemical methods. Although Au and Ag were synthesized using polyol process, the synthesis of Fe and its alloys has been found to be a challenge due to the limited reduction potential of polyols [24]. Later on, by enhancing the reduction potential of polyols using appropriate concentration of NaOH, Fe [25,26] and FeCo of varying compositions were successfully synthesized [27,28]. Furthermore, Huba et al. [29] prepared FeCo particles by slightly modifying the synthesis procedure; but the final particles showed irregular morphology and agglomeration compared to the previous reports. The physical properties of metals and their alloys are influenced not only by the size but also on the morphol- ogy of the nanoparticles [30–34]. Metals such as Au and Ag which are highly reducible and alloys such as CoNi could be synthesized with various morphologies like wires, cubes, spheres, plates, flow- ers, rice, and dumbbells using additives by polyol process [35–39]. Since the synthesis of FeCo by co-reduction of Fe and Co from its precursors depends on the experimental conditions such as temperature, type of precursor, NaOH concentration and the scheme of introducing the precursors into the solvent, morphology control is a challenge. The morphology of FeCo particles synthe- sized through polyol process was reported to be either spherical or cubic so far [27–29]. Moreover, properties of the FeCo particles such as the Curie temperature and bcc to fcc phase transition tem- perature were not discussed. In this paper, we report the synthesis of flower-like FeCo alloy particles by a simple one pot polyol pro- cess without any morphology controlling surfactants and report their compositional dependent properties. 0021-9797/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcis.2013.04.041 ⇑ Corresponding author. Fax: +91 0431 2500133. E-mail address: rjustinj@nitt.edu (R. Justin Joseyphus). Journal of Colloid and Interface Science xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Journal of Colloid and Interface Science www.elsevier.com/locate/jcis Please cite this article in press as: P. Karipoth et al., J. Colloid Interface Sci. (2013), http://dx.doi.org/10.1016/j.jcis.2013.04.041