Synthesis and Characterization of NiFe2O4 Magnetic Nanoparticles by Combustion Method

Synthesis and Characterization of NiFe2O4 Magnetic Nanoparticles by Combustion Method

Available online at SciVerse ScienceDirect J. Mater. Sci. Technol., 2013, 29(1), 34e38 Synthesis and Characterization of NiFe2O4 Magnetic Nanopartic...

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Available online at SciVerse ScienceDirect

J. Mater. Sci. Technol., 2013, 29(1), 34e38

Synthesis and Characterization of NiFe2O4 Magnetic Nanoparticles by Combustion Method M. Kooti*, A. Naghdi Sedeh Chemistry Department, College of Science, Shahid Chamran University, Ahvaz 61357-43169, Iran [Manuscript received April 17, 2012, in revised form June 9, 2012, Available online 24 December 2012]

Magnetic nanoparticles of nickel ferrite (NiFe2O4) have been successfully synthesized by microwave-assisted combustion method using stable ferric and nickel salts as precursors and glycine as fuel. The as-synthesized samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and field emission scanning electron microscopy (FESEM). The effect of different dose of glycine on the structural parameters and magnetic properties of the prepared NiFe2O4 nanoparticles was also investigated. This study revealed that it was possible to produce larger size of nanoparticles with lower saturation magnetization by using higher dose of fuel. KEY WORDS: Nanoparticles; Combustion; Microwave; Nickel ferrite; Glycine

1. Introduction Magnetic spinel ferrite nanocrystals are regarded as one of the most important inorganic materials because of their electronic, optical, electrical, magnetic and catalytic properties, all of which are different from their bulk counterparts. The spinel ferrites have the general formula of MFe2O4 (M ¼ Co2þ, Ni2þ, Zn2þ or other divalent metals) can be described as a cubic, closelypacked arrangement of oxygen atoms, and M2þ and Fe3þ ions can occupy either tetrahedral (A) or octahedral (B) sites[1,2]. Among various ferrites, nickel ferrite (NiFe2O4) is a typical inverse spinel, where Fe3þ ions are located in the tetrahedral (A) and octahedral (B) sites and Ni2þ ions are located in octahedral sites only. The magnetic moments of the tetrahedral and octahedral sublattices couple in an antiparallel manner and form a collinear ferrimagnetic ordering (Neel type) with the Curie temperature of about 870 K[3]. Powder of nanosized nickel ferrite is a useful material due to its high electromagnetic performance, excellent chemical stability and mechanical hardness, high coercivity, and moderate saturation magnetization. These unique properties of nickel ferrite make it a good contender for the application as soft magnets and low loss materials at high frequencies as well as ferro-fluids and biomedical material[4e7].

* Corresponding author. Prof.; E-mail address: [email protected] (M. Kooti). 1005-0302/$ e see front matter Copyright Ó 2013, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited. All rights reserved.

The properties of the synthesized NiFe2O4 are influenced by the composition, purity and microstructure, which are sensitive to the preparation methodology used in their synthesis. In order to achieve materials of the desired physical and chemical properties, the preparation of nickel ferrite nanocrystals through different routes has become an essential part of research and development. Many fabrication methods for preparation of nickel ferrite nanocrystals have been employed, namely by coprecipitation[8], hydrothermal methods[9], solegel methods[10], reverse micelles[11], chemical method[12], etc[13e15]. Although most of these methods have achieved particles of the required sizes and shapes, they require complicated procedures, expensive materials, high reaction temperatures, long reaction time, toxic reagents and by-products and potential harm to the environment. In this paper, we report the synthesis of nanosized nickel ferrite particles by combustion method using microwave heating and glycine as fuel. The employed combustion method can produce fine, high-purity, stoichiometric nickel ferrite particles in very short time. The nanostructure and magnetic properties of the asprepared nickel ferrite as well as the effect of different amounts of fuel were also investigated. 2. Experimental 2.1. General All materials were of commercial reagent grade and obtained from Merck and Fluka. The combustion reactions were carried out using solid state precursors and the heat for reactions was supplied by a microwave oven with a nominal power of 1000 W.

M. Kooti and A.N. Sedeh: J. Mater. Sci. Technol., 2013, 29(1), 34e38


of (6, 8 and 10):1:2, respectively. These samples are designated as S1, S2 and S3. 3. Results and Discussion Nickel ferrite nanoparticles were synthesized by the combustion method using glycine as fuel. In this procedure, glycine (CH2NH2COOH) was employed as the fuel due to its more negative heat of combustion (3.24 kcal g1) as compared to urea (2.98 kcal g1) and citric acid (2.76 kcal g1)[16]. The XRD patterns of samples are shown in Fig. 1. The diffraction peaks observed at 2q ¼ 30.40 , 35.77 , 43.51 , 53.98 , 57.39 and 63.04 correspond to the planes of (220), (311), (222), (400), (422), (511) and (440), respectively. The observed peaks for sample S3 have relative intensity (%) of 26.6, 100, 39.1, 15.9, 42.0, and 57.8, respectively. These angles measured for the NiFe2O4 samples are in very good agreement with the reported values (JCPDS card No. 441485). The diffraction lines provide clear evidence for the formation of cubic phase of pure inverse spinel structure of nickel ferrite with Fd3m space group. The particle size of NiFe2O4 samples has been calculated from the XRD line broadening of (311) peak using DebyeeScherrer’s formula[17] D ¼ Bl=bcos q

Fig. 1 XRD patterns of NiFe2O4 nanoparticles: (a) S1, (b) S2, (c) S3 (- peaks for impurity).

X-ray diffraction (XRD) patterns of the samples were taken with a PW1840 Philips X-ray diffractometer at room temperature using CuKa radiation wavelength of l ¼ 0.15418 nm. The peak position and intensity were obtained between 10 and 80 with a velocity of 0.02 /s. The morphology and size of the particles were examined by transmission electron microscopy (TEM) using a Philips CM10-HT 100 KV microscope. The field emission scanning electron microscopy (FESEM) images were obtained using a Hitachi Japan S4160 field emission scanning electron microscope. Magnetic properties of nickel ferrite nanocrystals were studied using vibrating sample magnetometer (VSM) from Meghnatis Daghigh Kavir Company.

where D is the crystallite size (nm) of the phase under investigation, B is the Scherrer constant (0.9), l is the wavelength of X-ray (l ¼ 0.154 nm), b is the full-width at half maximum (FWHM) of plane (311) and q is the Bragg’s angle. The calculated crystallite size of NiFe2O4 for samples S1, S2, and S3 are found to be 34.7, 38 and 42 nm, respectively. These results revealed that increasing the amount of glycine fuel, from samples S1 to S3 causes enlargement of crystallite size of NiFe2O4 nanoparticles. An X-ray analysis enable us to investigate the role of the amount of fuel in the change of the structural parameters of nickel ferrite such as the crystallite size (D), lattice constant (a), unit cell volume (V) and density (d). The lattice constants of all the samples are calculated using the following relation[17]

2.2. Procedure a ¼ dhkl h2 þ k 2 þ l2 The NiFe2O4 nanoparticles were synthesized by a combustion method using glycine as fuel. In this synthesis calculated proportions of nickel and iron nitrates with known amount of glycine were thoroughly mixed. The obtained dark red liquid was transferred into a porcelain crucible and then heated in a microwave for 2 min with 30% power. During heating of the mixture a great deal of foams produced and spark appeared which spread through the mass, yielding a brown voluminous and fluffy product in the container. The final product was washed several times with deionized water and ethanol and dried at 100  C for 3 h. Three samples of NiFe2O4 have been prepared using glycine: Ni(NO3)2$6H2O:Fe (NO3)3$9H2O in molar ratios


The values are in good agreement with earlier reported values of 0.833 nm for nano NiFe2O4[18] and 0.8339 nm for the bulk NiFe2O4[19], which prove the efficiency of our synthesis technique. The calculated values of various structural parameters are given in Table 1. Furthermore, in both samples S1 and S2 a peak at 2q ¼ 33.42 , attributed to a-Fe2O3 phase impurity is seen but in sample S3, where a high dose of glycine was used, this peak disappeared. The FT-IR spectrum of the as-prepared NiFe2O4 is presented in Fig. 2. A broad absorption band at about 3400 cm1 represents a stretching mode of H2O molecules and OH

Table 1 Structural parameters of nickel ferrite calculated from XRD results Glycine/mmol


Space group

Crystallite size/nm

Lattice constant/nm



6 8 10

fcc fcc fcc

Fd3m Fd3m Fd3m

34.7 38 42

0.8322 0.8294 0.8321

5.404 5.459 5.405

0.5760 0.570 0.5761


M. Kooti and A.N. Sedeh: J. Mater. Sci. Technol., 2013, 29(1), 34e38

Fig. 2 FT-IR spectrum of NiFe2O4 nanoparticles. Fig. 4 TEM image of as-prepared NiFe2O4 nanoparticles (sample S3). [15]

groups . Two other principle absorption bands in the range of 400e600 cm1 are also observed in the FT-IR spectrum. The first band (n1) is around 459 cm1 and the second one (n2) is around 563 cm1, attributed to the long bond length of oxygene metal ions in the octahedral sites and shorter bond length of oxygenemetal ions in the tetrahedral sites in the spinel structure, respectively[20]. Three samples S1, S2, and S3 show the same IR spectra and Fig. 2 is the IR spectrum of S1. The morphology and particle sizes of the as-prepared nickel ferrite nanoparticles were determined by FESEM and TEM techniques. As it can be seen from Fig. 3, the FESEM images show the presence of voids and pores in the samples. This is attributed to the release of large amount of gases during combustion process. The samples have spongy structure and the formation of multigrain agglomerations consisting of very fine crystallites. In sample S3 (Fig. 3(c)), where a high molar ratio of glycine was used, most of pores on the surface have smaller size and the particles are more packed. This is due to the release of more heat during the combustion, which causes the fusion of the NiFe2O4 nanoparticles. The TEM micrographs of the as-fabricated NiFe2O4 nanoparticles (sample S3) is given in Fig. 4 showing almost homogeneous and uniform distribution of these particles in the powder sample. The particles consisted of some regular and irregular polyhedrons with mean sizes of about 35 nm, which is in close agreement with the size obtained from XRD analysis. Magnetic measurements of as-prepared NiFe2O4 were carried out at room temperature using vibrating sample magnetometer (VSM) with a peak field of 10 kOe and the hysteresis loops for samples S1, S2, and S3 are shown in Fig. 5. As it can be seen, the variation of magnetization as a function of applied field presents a narrow cycle and the observed hysteresis loops are characteristic behavior of soft magnetic material. Saturation magnetization (Ms), remanence magnetization (Mr) and coercivity (Hc) values of these ferrites are given in Table 2. The saturation magnetization of NiFe2O4 samples nearly

approaches the value of bulk NiFe2O4 (56 emu g1)[21]. For most magnetic nanoparticles, the saturation magnetization is much lower than bulk value due to the surface spin disorder[22,23] and decreases with decreasing particle size[24]. Among the three synthesized nickel ferrite samples, sample S3, which was prepared using higher dose of fuel, has the least value of Ms. The magnetic saturation of the synthesized NiFe2O4 with pure phase (sample S3) is 48.75 emu g1, which is an acceptable value for this size as reported in literature[25e28] and relatively low in comparison with the corresponding bulk NiFe2O4. A similar decrease in the saturation magnetization was observed for cobalt ferrite, which is also an inverse spinel with collinear ferrimagnetic spin structure in the bulk form[29]. Nickel ferrite is a typical soft ferromagnetic material, whose magnetic behavior depends significantly on the synthesis route and the particle size. For relatively larger particles, magnetic domains are formed to reduce the static magnetic energy. The number of domains diminishes with decreasing particle size. The particles turn into single domain ones with their size under a critical radius (for nickel ferrite, this parameter is about 100 nm), resulting in the increase of coercive force due to vanishing of the magnetization caused by the movement of domain walls. Back to our finding of the variation of Ms from samples S1 to S3, the higher value of Ms for samples S1 and S2 compared to sample S3 could be attributed to the presence of some Fe2O3 impurities in samples S1 and S2 as shown in the XRD patterns of these samples. These paramagnetic impurities may have some contribution to the magnetization that resultantly increases the saturation magnetization of nickel ferrite nanoparticles. In addition to this parameter, the variation of saturated magnetization and coercivity of NiFe2O4 nanoparticles may be also explained on the basis of various factors such as cation redistribution, surface spin, formation of spin glass structures, and magneto crystalline anisotropy.

Fig. 3 FESEM images of NiFe2O4 nanoparticles: (a) S1, (b) S2, (c) S3.

M. Kooti and A.N. Sedeh: J. Mater. Sci. Technol., 2013, 29(1), 34e38


4. Conclusion

Fig. 5 Hysteresis loops of as-prepared NiFe2O4 nanoparticles.

Table 2 Magnetic properties of the as-fabricated NiFe2O4 nanoparticles Sample




S1 S2 S3

60.87 51.86 48.75

17.44 18.36 18.95

112.62 137.12 177.55

Therefore, the magnetic behavior of nanosized nickel ferrites can be a collective effect of these interactions[30,31]. It is worth noting that the magnetic properties of similar ferrite nanoparticles of the same particle size differ depending on the preparation method used. As stated by Naseri et al.[9], pairs of similar spinel ferrite nanoparticles of the same particle size have different saturation magnetization values and coercivity fields. This fact indicates that, the magnetic properties of ferrites are related primarily to the preparation methods. The Ms value of sample S3 also supports the fact that in this sample Ni2þ ions (almost) entirely locate in B sites because due to the lower spin moment of Ni2þ (S ¼ 2 mB/ion) compared to that of Fe3þ (S ¼ 5 mB/ion), the occupation of Ni2þ ions in A sites would result in an increase of the net magnetization according to the Neel configuration. Finally, to give an idea about the advantage of the method for synthesizing NiFe2O4 nanoparticles, we compared our method with those reported earlier, listed in Table 3. As can be seen in Table 3, the reaction conditions of our method are much superior to the methods illustrated in this table. The properties of our fabricated NiFe2O4 sample appear to be either better than some of those presented in this table or comparable with those reported by Umare et al[33].

Table 3 Comparison of reaction conditions and properties of our NiFe2O4 sample with those reported earlier Method of preparation


70  C/3 h, 700  C/10 h Co-precipitation 80  C/40 min, 600  C/10 h Hydrothermal 180  C/10 h Combustion 80  C/2 h, 800  C/2 h Hydrothermal 180  C/10 h Thermal 80  C/24 h, 821  C/3 h treatment Combustion Microwave/2 min Solegel

Hc/Oe Reference Grain Ms/ size/nm (emu/g) 45








65 35

49.6 42.5

30 112.3

[32] [33]

80 47

53.6 29.05

68 51

[18] [9]



177.5 This work

Combustion method with microwave heating was used to synthesize nickel ferrite nanoparticles in high yield and purity. A mixture of Fe (III) and Ni (II) nitrates with glycine as fuel was heated in a microwave to afford nanosized NiFe2O4, which was characterized by various techniques, mainly XRD, FT-IR, FESEM, TEM and VSM. The effect of different amounts of fuel, i.e. glycine, on the size and purity of the prepared nickel ferrite nanoparticles was also investigated. The microwave combustion method can be considered as a facile and rapid route for the preparation of nanoscale NiFe2O4. Moreover, there is no need for expensive precursors or complicated treatments in this method. Acknowledgment The authors are grateful for the financial support provided by the Research Council of Shahid Chamran University, Ahvaz, Iran. REFERENCES [1] B. Aslibeiki, P. Kameli, H. Salamati, M. Eshraghi, T. Tahmasebi, J. Magn. Magn. Mater. 322 (2010) 2929e2934. [2] S.C. Tsang, V. Caps, I. Paraskevas, D. Chadwick, D. Thompsett, Angew. Chem. Int. Edit. 43 (2004) 5645e5649. [3] B.D. Cullity, S. Graham, Introduction to Magnetic Materials, Wiley, New York, 2009. [4] L.Y. Chen, H. Dai, Y.M. Shen, J.F. Bai, J. Alloys Compd. 491 (2010) L33eL38. [5] D.S. Mathew, R.S. Juang, Chem. Eng. J. 129 (2007) 51e65. [6] I. Sharifi, H. Shokrollahi, S. Amiri, J. Magn. Magn. Mater. 324 (2012) 903e915. [7] M.R. Phadatare, V.M. Khot, A.B. Salunkhe, N.D. Thorat, S.H. Pawar, J. Magn. Magn. Mater. 324 (2012) 770e772. [8] M.S. Niasari, F. Davar, T. Mahmoudi, Polyhedron 28 (2009) 1455e1458. [9] M.G. Naseri, E.B. Saion, H.A. Ahangar, M. Hashim, A.H. Shaari, Powder Technol. 212 (2011) 80e88. [10] M. Mozaffari, Z. Abooalizadeh, J. Amighian, J. Magn. Magn. Mater. 323 (2011) 2997e3000. [11] A. Kale, S. Gubbala, R.D.K. Misra, J. Magn. Magn. Mater. 277 (2004) 350e358. [12] P. Deb, A. Basumallick, S. Das, Solid State Commun. 142 (2007) 702e705. [13] L. Chen, Y. Yuan, H. Peng, X. Lu, Z. Luo, Mater. Lett. 67 (2012) 311e314. [14] J. Wang, F. Ren, R. Yi, A. Yan, G. Qiu, X. Liu, J. Alloys Compd. 479 (2009) 791e796. [15] V.K. Sankaranarayana, C. Sreekumar, Curr. Appl. Phys. 3 (2003) 205e208. [16] C.C. Hwang, J.S. Tsai, T.H. Huang, Mater. Chem. Phys. 93 (2005) 330e336. [17] B.D. Cullity, Elements of X-ray Diffraction, second ed., AddisonWesley, London, 1978. [18] J. Huo, M. Wei, Mater. Lett. 63 (2009) 1183e1184. [19] M. Srivastava, S. Chaubey, A.K. Ojha, Mater. Chem. Phys. 118 (2009) 174e180. [20] P. Laokul, V. Amornkitbamrung, S. Seraphin, S. Maensiri, Curr. Appl. Phys. 11 (2011) 101e108. [21] V. Sepelak, K. Tkacova, V.V. Boldyrev, S. Wibmann, K.D. Becker, Physica B 234e236 (1997) 617e619. [22] S. Rana, R.S.M. Srivastava, M. Sorensson, R.D.K. Misra, Mater. Sci. Eng. B 119 (2005) 144e151. [23] R.D.K. Misra, S. Gubbala, A. Kale, W.F. Egelhoff Jr., Mater. Sci. Eng. B 111 (2004) 164e170.


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