Advances in Nanoparticles, 2013, 2, 378-383 Published Online November 2013 (http://www.scirp.org/journal/anp) http://dx.doi.org/10.4236/anp.2013.24052 Open Access ANP Synthesis and Characterization of Ni-Zn Ferrite Nanoparticles (Ni 0.25 Zn 0.75 Fe 2 O 4 ) by Thermal Treatment Method Poh Lin Leng 1 , Mahmoud Goodarz Naseri 2* , Elias Saion 1 , Abdul Halim Shaari 1 , Mazaliana Ahmad Kamaruddin 1 1 Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang, Malaysia 2 Department of Physics, Faculty of Science, Malayer University, Malayer, Iran Email: * mahmoud.naseri55@gmail.com Received August 14, 2013; revised October 2, 2013; accepted October 16, 2013 Copyright © 2013 Poh Lin Leng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Cubic structured nickel-zinc ferrite nanoparticles (Ni 0.25 Zn 0.75 Fe 2 O 4 ) have been synthesized by thermal treatment method. In this procedure, an aqueous solution containing metal nitrates as precursors, polyvinyl pyrrolidone as a cap- ping agent, and deionized water as a solvent were thoroughly stirred, dried at 353 K for 24 h, and crushed into powder before calcination to remove organic matters and crystallize the particles. The structure and particle size were charac- terized by X-ray powder diffraction and transmission electron microscopy. The average particle size increased from 7 to 25 nm with increase of calcination temperature from 723 to 873 K respectively. The magnetic properties were deter- mined by vibrating sample magnetometer and electron paramagnetic resonance electron paramagnetic resonance at room temperature. By increasing the calcinations temperatures from 723 to 873 K it showed an increase of the mag- netization saturation from 11 to 26 emu/g and the g-factor from 2.0670 to 2.1220. The Fourier transform infrared spec- troscopy was used to confirm the presence of metal oxide bands at all temperatures and the removal of organic matters at 873 K. Keywords: Thermal Treatment; Nickel Zinc Ferrite; Nanoparticles; Magnetic Property 1. Introduction The last two decades have seen a remarkable progress in the synthesis of spinel ferrites nanocrystals, aiming at a better material with excellent chemical stability, low magnetic coercivity, moderate saturation magnetization, high permeability, high electrical resistivity and low eddy current. In particular, the nickel-zinc (Ni-Zn) ferrite nanocrystals have been extensively studied for their su- per-paramagnetic properties, which are suitable for high- frequency applications such as rod antennas and cores of inductors and transformers [1,2]. The magnetic proper- ties of ferrites of spinel structural formula AB 2 O 4 are mainly controlled by the divalent cations, which occupy the tetrahedral A sites and the trivalent cation, which has high degree affinity for octahedral B sites [3,4]. Zn fer- rite bulk material has a normal spinel structure, where all divalent cations are located on the tetrahedral sites and trivalent cations all located on the octahedral sites. Ni ferrites bulk materials on the other hand have an inverse spinel structure, where half of trivalent cations occupy the tetrahedral sites while the other half remain on octa- hedral, while divalent cations all migrate to octahedral positions. It has been shown that for the Ni-Zn ferrite nanoparticles, octahedral sites prefer for Ni and tetrahe- dral prefers for Zn [5]. Substituting Zn for Ni cations leads to the formula ( 2 x Zn  3 1x Fe   ) ( 1x Ni  3 1x Fe   )O 4 (0 ≤ x ≤ 1), in which the first and second brackets indicate oc- cupancy of the A and B sub-lattices respectively. Beside the distribution of divalent and trivalent cations in the spinel structure, the properties of Ni-Zn ferrite nanopar- ticles are highly sensitive to the quantum confinement effect of particle size, which in turn depends on the method of preparation of the nanoparticles [6]. A variety of methods have been proposed for the syn- thesis of Ni-Zn ferrite nanoparticles with controllable size, shape, and chemical stability such as sol-gel methods [7], * Corresponding author.