Preparation, Morphological and Structural Properties of Nanocrystalline Ni–Mg Cobalt-Ferrite Synthesized by the Co-Precipitation Method R. M. Rosnan a* , Z. Othaman b , A.A. Ati c Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru, Malaysia. a* rizuanmr@gmail.com, b zulkafliothaman@utm.my c aliphysics1@yahoo.com Keywords: Co 0.5 Ni 0.5−x Mg x Fe 2 O 4 · Spinel nanoferrites · co-precipitation · cobalt ferrite Abstract. The present study describes the morphological and structural characterization of nanosized Ni-Mg cobalt-ferrites. The nominal compositions Co 0.5 Ni 0.5−x Mg x Fe 2 O 4 in the range (0.0 ≤ x ≤ 0.5) have been synthesized by co-precipitation method. These nano-powder products were sintered in furnace at temperature of 900°C for 10 hour with a heating rate of 5°C/min to obtain these ferrites. The prepared nano-ferrites were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) with varying concentration (x) in the composition of the prepared nanoferrites. XRD confirmed formation of single phase spinel ferrite with average crystalline size in the range of 34–37 nm. Lattice constant (a) increases with an increase of Mg concentration. Further information about the structure and morphology of the nanoferrites was obtained from FESEM and results are in good agreement with XRD. Introduction Cobalt ferrites, CoFe 2 O 4 are among the most widely used magnetic materials having low cost, high performance for high frequency applications. CoFe 2 O 4 with an inverse spinel structure is well known to have a relatively large magnetic anisotropy, moderate saturation magnetization, remarkable chemical stability, and mechanical hardness [1]. These properties, along with their great physical and chemical stability, make CoFe 2 O 4 nanoparticles for potential applications in magnetic data storage systems, electromechanical transducers and biomedicine. The magnetic character of the particles used for recording media depends crucially on the size, shape and purity of these nanoparticles. These particles should be single domain, of pure phase, having high coercivity and medium magnetization [2]. Hence the need for developing fabrication processes that are relatively simple and yield controlled particle sizes. In view of the important technological applications of spinel ferrites nanoparticles, the synthesis of magnetic systems with characteristic nanoscale dimension has attracted considerable attention. The co-precipitation method offers a synthesis route for the production of ferrite, which are low cost, uniform and non-aggregated. In this research, novel Nickel-Magnesium substituted of Cobalt ferrite was synthesized. The Co-Ni-Mg Fe 2 O 4 nanoparticle was primarily prepared by co-precipitation method. The prepared nano-ferrites were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) with varying concentration (x) in the composition of the prepared nanoferrites. Methods And Procedures Preparation of Ni-Mg substituted cobalt ferrite nanoparticles. The polycrystalline powders of series Co 0.5 Ni (0.5−x) Mg (x) Fe 2 O 4 (0.0 ≤ x ≤ 0.5) in steps of 0.1 were prepared by the chemical co- precipitation route. The stoichiometric amounts of Ni(NO 3 ) 2 ∙6H 2 O, Mg(NO 3 ) 2 ∙6H 2 O, Co(CH 3 COO) 2 ∙4H 2 O and Fe(NO 3 ) 3 ∙9H 2 O were introduced. All aqueous solutions are dissolved in distilled water, heated up to 90°C and stirred for 2 hours. To obtain ferrites of a smaller, less dispersed and more homogeneous, the mixing of reagents is performed by addition of NaOH drop- wise into the metal solutions. For the transformation of hydroxides into ferrites (dehydration and atomic rearrangement involved in the conversion of intermediate hydroxide phase into ferrites), it is recommended to maintain a temperature of 90 °C for another 20 minutes. The precipitates are then thoroughly washed several times, and overnight dried at 200 °C to remove water contents. The Advanced Materials Research Vol. 1109 (2015) pp 355-359 Submitted: 2014-07-27 © (2015) Trans Tech Publications, Switzerland Accepted: 2014-12-11 doi:10.4028/www.scientific.net/AMR.1109.355 Online: 2015-06-10 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 124.82.93.215-20/10/15,18:52:45)