ORIGINAL PAPER Ultrasound-Assisted Synthesis and Tuning the Magnetic and Structural Features of Superparamagnetic Fe 3 O 4 Nanoparticles by Using Ethylenediamine as a Precipitating Agent Komail Boustani 1 & Aliasghar Shokri 1 & Saber Farjami Shayesteh 2 & Atefeh Jafari 2 Received: 7 November 2019 /Accepted: 21 January 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Due to the strong effect of nanoparticles’ size on the magnetic and structural properties of Fe 3 O 4 (magnetite) nanoparticles, the size selection proportional to desired magnetization especially superparamagnetic characteristic of these particles is very impor- tant. In this work, at first, the Fe 3 O 4 nanoparticles successfully synthesized by a novel precipitating agent, ethylenediamine (EN), with an ultrasonic treatment (40 kHz, 150 W) by the co-precipitation method. Then, in order to accurately investigate the synthesis conditions on the physical properties of Fe 3 O 4 , the influence of reaction temperature, reaction time, and precipitating agent are studied. The structural and magnetic properties of the as-prepared nanoparticles are characterized by X-ray diffraction (XRD), Rietveld refinement, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analysis. It is found that the EN produces magnetite nanoparticles with a larger size and desired saturation magnetization (M s ). The absence of impurity phases in all of the synthesized nanoparticles and formation of the spinel structures at low temperature (30 °C) can be due to the influence of the ultrasound waves. Keywords Superparamagnetic Fe 3 O 4 . Ethylenediamine . Magnetic properties . Ultrasonic irradiation 1 Introduction Even after decades, due to the high potential of superparamagnetic iron oxide (Fe 3 O 4 ) nanoparticles in many technological areas such as magnetic storage media, catalysis, waste water, lithium ion battery, biosensing applications, and in medical applications, for example, as a targeted drug delivery, contrast agent in the magnetic resonance imaging (MRI) and cell separation, the study of its magnetic properties still con- tinues [1–7]. The popularity of Fe 3 O 4 (magnetite) nanoparticles for use in various fields, especially in medical applications, is in addition to its superior magnetization, its non-toxicity and sta- bility under physiological conditions [5, 8–10]. Because of the size-dependent nature of magnetic properties, in particularly the behavior of superparamagnetism, which is very attractive for many applications, research on the tuning of particle size with desired saturation magnetization (M s ) and coercivity (H c ) is worthwhile. So, this article has been devoted to this issue. The synthesis method plays an important role in the prop- erties of produced nanoparticles [11]. To date, the magnetite nanoparticles have been synthesized by various methods, such as co-precipitation, sol-gel, hydrothermal, and etc. [10, 12]. There are several reports about the study of synthesis method and reaction condition effects on the physical properties of the magnetite nanoparticles [10, 11, 13, 14]. The co-precipitation as a convenient way for preparation of magnetite nanoparti- cles is a very facile method and can be combined with other rout like ultrasound irradiation. Various people have been working on the synthesis of magnetic nanoparticles, including iron oxide, using acoustic waves and applying them in differ- ent areas [12, 15–17]. Almessiere et al. fabricated ferrites by sonochemical way [18–20]. Wei et al. [21] used sonochemical method for improving the property of calcium ferrite. Mahdiani et al. [22] investigated the experimental and instru- mental parameters on properties of PbFe 12 O 19 nanostructures * Komail Boustani komailboustani@shargh.tpnu.ac.ir 1 Department of Physics, Payame Noor University, P. O. Box 19395-3697, Tehran, Iran 2 Nanostructure Lab, Physics Department, University of Guilan, Rasht, Iran https://doi.org/10.1007/s10948-020-05436-y Journal of Superconductivity and Novel Magnetism (2020) 33:1879–1887 Published online: 7 February 2020 /