STRUCTURAL CHARACTERIZATION OF CuFe2O4 NANOCOMPOSITES AND SYNTHESIS BY AN ECONOMICAL METHOD.
ABSTRACT: Copper ferrites were prepared through co-precipitation technique. The aim of this effort was to present a novel and economical method of preparation of copper ferrites via co-precipitation technique. Structural properties were studied with the help of XRD technique while micro structural study of the samples was carried out by SEM. The particle size was calculated with the help of Scherrer's formula using characteristic peaks. The SEM images showed uniformity and homogeneity of the synthesized CuFe2O4 particles.
Key words: Copper ferrite, Low cost ferrites, Co-precipitation
Ferrites (CuFeO4) have paramount advantages over other types of magnetic materials like high electrical resistivity and resultant low eddy current losses over a wide range of frequency. For the most favorable combination of low cost, high quality, high stability, and lowest volume, ferrites are considered to be the best core material choice for frequencies from 10 KHz to 50 MHz. Ferrites offer an unmatched flexibility in magnetic and mechanical parameters . The development and consistent successes in switch-mode power supplies is continuously encouraging the ferrite industry to produce new, high quality ferrite cores capable of operating at increasingly higher frequency . The ferrite particles can be used for the synthesis of temperature sensitive magnetic fluid with higher magnetization and magnetization-temperature gradient .
Of all magnetic materials, ferrites are the most useful because in addition to many magnetic properties, they are also good electrical insulator, unlike the ferromagnetic me als. Thus losses due to free electrons are eliminated. The crystallography, electrical and magnetic properties of ferrites depend upon the chemical composition as well as on the various heat treatments during the course of preparation . Different studies have been made to synthesize copper ferrites by using different techniques. These studies revealed that the magnetic performances and microstructure depend considerably on chemical composition and sintering temperature of samples . Ferrite shrinks when sintered, depending on the specific ferrite, this shrinkage can range from 10% to 17% in each dimension. The grain size significantly increases with increasing copper contents and sintering temperature Ts also affects the densification, grain growth and initial magnetic permeability of the samples .
Hankare and co-workers  used oxalate precipitation method to synthesize single-phase Cu-Co ferrite. Wang et al.  used NaOH as precipitant to fabricate Cu-substituted NiZn ferrite and confirmed the formation of cubical spinel structure at all the temperatures for calcinations and sintering. Yang et al.  synthesized copper ferrite (CuFe2O4) by using three different techniques, citric acidassisted sol-gel method, solid-state reaction and co-precipitation method. Conventional oxide ceramic process have been applied by Ahmed et al.  to synthesize nano-crystalline copper ferrite and indicated that with a firing temperature of 1100 degC, the samples have higher bulk density (3.93 g/cm3), whereas at 1200 degC higher saturation magnetization (45.2 emu/g) and lower co-ercivity (6.13 Oe). Various publications also explain successful synthesis of nanosized copper ferrites, and their characterizations [11, 12, 13].
The current effort has been focused to synthesize a low cost copper ferrite via co-precipitation tchnique. Of all these techniques, chemical co-precipitation seems to be the most convenient to synthesize nanoparticles because of its simplicity and better control over crystallite size and other properties of the materials . Characterization has been done using X-ray diffraction and scanning-electron microscope.
2. EXPERIMENTAL SECTION
2.1 Chemicals. Ferrous Sulphate anhydrous (FeSO4), Citric Acid (C2H4O2), and Ethylene Glycol (C6H8O7) were purchased from Merck where as Copper Sulphate (CuSO4) and Sodium Hydroxide (NaOH) were purchased from Fischer and Sigma Aldrich respectively.
2.2 Instruments. X-ray diffraction (XRD) experiments were performed with PANanalytical, Philips and scanning electron microscopic (SEM) images were captured by using JEOL-JSM 5910. For SEM each sample was prepared and coated by gold in Spi-Module Sputter Coater because Scanning Electron Microscopy requires conductor material to analyze the morphology of samples.
2.3 Preparation of Copper Ferrites. Cu ferrites (CuFe2O4) were prepared according to the method adopted by Shin et al.  with minor changes. They synthesized CuFe2O4 with metallic chlorides and used KOH (5N) as precipitant by maintaining pH 10 but we used NaOH (1N) as precipitant and metallic sulphates by maintaining pH 12. The total molarity of the metallic ion solution was kept constant. The samples of CuFe2O4 were prepared by co-precipitation from CuSO4 and FeSO4 salts and citric acid was added to act as complexent. Shin and co-workers mixed the chloride salts with KOH at temperature of 353K but we mixed at room temperature. The bath temperature was maintained at 85 oC. The blackish brown precipitates so obtained were washed several times with de-ionized water till filtered water of precipitates attained pH 7 and finally washed by acetone several times. The bath temperature was maintained at 85 oC.
The final product was dried in oven for 6 to 8 hrs at 50 oC and grinded to fine powder with the help of pestle and mortar. The micro structural characteristics were examined via XRD technique and Scherrer's formula was used to find crystallite size (t = 0.9 ? / B cos ?B, , where ? is the wavelength of the X-rays used. B is deducted from the characteristic peak at full width half maximum (FWHM).
3. RESULTS AND DISCUSSION
We have successfully employed co-precipitation technique and synthesized the Copper ferrites; results were compared with that of Shin et al's  results and were found in a close agreement. In the present work, synthesized copper ferrite showed all the peaks of XRD pattern in close agreement with JCPDS card no. 00-025-0283. There were additional peaks corresponding to extra phases such as a-Fe2O3 which showed incomplete reaction. Crystallite size was estimated in nm . The analysis of the peak positions and the relative intensities of the diffracted lines of the synthesized copper ferrites were compared with XRD pattern of Gomes et al. . By comparing the XRD patterns of the prepared samples, it was found that these were not indexed to single phase of spinal structure. Particle size of each sample was calculated with strongest diffraction peak (311), Fig.1. It was observed that broadening of diffraction peak (311) was directly relating to the particle size.
So in this regard Scherrer's formula was used to find the crystallite size. The previous study clearly depicts that the pH of the solution has important factor regarding the ferrite formation. In the present study we maintain the pH of the solution at 12.
In sample K1A four peaks out of seven major peaks have been matched with the standard pattern of CuFe2O4. The peaks with miller indices (222), (400), (533) did not match with the standard pattern of CuFe2O4. The following miller indices (422), (333) and (622) were not present in our synthesized CuFe2O4. The synthesized CuFe2O4 was found out with FCC structure. Lattice constants have been presented in table 1.
In sample K2A six peaks out of eight major peaks were found out in close agreement with the standard patterns of CuFe2O4. The peaks with miller indices (111) and (422) did not match with the standard pattern of CuFe2O4, Fig. 2. The following miller indices (400) and (300) were not present in the synthesized CuFe2O4. The structure CuFe2O4 was found to be FCC. Lattice constants have been listed in table 2.
Table 1: Peak analysis of XRD Pattern of Sample K1A
2 (deg)###(deg)###I/Imax %###(hkl)###d-value###a (A)
The above table confirmed the miller indices and lattice constants. The average lattice constant was 8.24(?). The X-ray density was calculated 5.67g/cm3!.
Table 2: Peak analysis of XRD Pattern of Sample K2A
2 (deg)###(deg)###I/Imax %###(hkl)###d-value###a (A)
The above table confirmed the miller indices and lattice constants. The average lattice constant was 8.31(?). The X-ray density was calculated 5.53g/cm3!.
Homogeneous CuFe2O4 nanoparticles were prepared by simple and economical chemical co-precipitation method at room temperature. It is reported that the water bath temperature, 85 oC, is the temperature where the most suitable results can be obtained.
Samples Particle size (XRD)
TabTable 3: Particle sizes obtained from X-ray diffraction technique.
The authors would like to acknowledge Department of Physics University of Agriculture Faisalabad for technical assistance and greatly indebted to the University Sains Malaysia (USM) for providing state of the art facilities and graduate assistantship (GA).
1. Z. Huang, G. Yin, X. Liao, Y. Yao and Y. Kang. Preparation and magnetic properties of Cu-ferrite nanorods and nanowires. Journal of Colloid and Interface Science, 317, 530-535(2008)
2. C. R. Hendries and W. R. Amarakoon. Processing of Maganese Zinc Ferries for High-Frequency Switch-Mode Power Supplies. C. Bulliten, 70, 890-896(1991)
3. B. Jeyadevan, C. N. Chinnasamy, K. Shinoda and K. Tohji. Mn-Zn ferrite with higher magnetization for temperature sensitive magnetic fluid. Journal of Applied Physics, 93, 450-455(2003)
4. H. Y. Luo. Z. X. Yue and J. Zhou. Synthesis and high-frequency magnetic properties of sol-gel derived Ni-Zn ferrite for sterite composites. Journal of Magnettism and Magnetic Materials, 210,104-108(2000)
5. M. Feder, O. Caltuns and V. Valceanu. Microstructure and magnetic properties of ni-zn-cu ferrites sintered at different temperatures. Fizica Starii Condensate, 98-103(2001)
6. M. M. Haque. M. Huq and M.A. Hakim.. Influence of CuO and sintering temperature on the microstructure and magnetic properties of Mg-Cu-Zn ferrites. Journal of Magnetism and Magnetic Materials, 320, 2792-2799(2008)
7. P. P. Hankare, P.D. Kamble, M.R. Kadam, K.S. Rane and P.N. Vasambekar. Effect of sintering temperature on the properties of Cu-Co ferrites prepared by oxalate precipitation method. Materials Letters, 61, 2769-2771(2007)
8. H. Wang, J. Liu, W. Li, J. Wang, L. Wang, L. Song, S. Yuan and F. Li. Structural, dynamic magnetic and dielectric properties of Ni0.15Cu0.2Zn0.65Fe2O4 ferrite produced by NaOH co-precipitation method. Journal of Alloys and Compounds, 461, 373-377(2008)
9. H. Yang, J. Yan, Z. Lu, X. Cheng and Y. Tang. Photocatalytic activity evaluation of tetragonal CuFe2O4 nanoparticles for the H2 evolution under visible light irradiation. Journal of Alloys and Compounds, 33, 568-575(2008)
10. Y. M. Z. Ahmed, M. M. Hessien, M. M. Rashad and I.A. Ibrahim. Nano-crystalline copper ferrites from secondary iron oxide (mill scale). Journal of Magnetism and Magnetic Materials, 321, 181-187(2009)
11. D. Gingasu, I. Mindrua, L. Patrona and C. Cizmas. Tetragonal copper ferrite obtained by self-propagating combustion. Journal of Alloys and Compounds, 460, 627-631(2008)
12. T. Liu, L. Wang, P. Yang and B. Hu. Preparation of nanometer CuFe2O4 by auto-combustion and its catalytic activity on the thermal decomposition of ammonium perchlorate. Materials Letters, 62, 4056-4058(2008)
13. W. Lv, Bo Liu, Z. Luo, X. Ren and P. Zhang. XRD studies on the nanosized copper ferrite powders synthesized by sonochemical method. Journal of Alloys and Compounds, 465, 261-264(2008)
14. I.H. Gul, W. Ahmed and A. Maqsood. Electrical and magnetic characterization of nanocrystalline Ni-Zn ferrite synthesis by co-precipitation route. Journal of Magnetism and Magnetic Materials, 320, 270-275(2008)
15. H. C. Shin, S. C. Choi, K. D. Juung and S. H. Han. Mechanism of M ferrites (M = Cu and Ni) in the CO2 Decoposition Reaction. Chem. Mater, 13, 1238-1242(2001)
16. B. D. Cullity. Elements of x-ray diffraction. 2nd edition. Addison wesley publishing company, canada(1978)
17. R. K. Selvan, C. O. Augustin, V. Sepelak, L. J. Berchmans, C. Sanjeeviraja and A. Gedanken. Synthesis and characterization of CuFe2O4/CeO2 nanocomposites. Materials Chemistry and Physics, 112, 373-380(2008)
18. J.A. Gomes, M.H. Sousa, G. J. da Silva, F.A. Tourinho, J. Mestnik-Filho, R. Itrid,G.de M. Azevedo, J. Depeyrot. Cation distribution in copper ferrite nanoparticles of ferrofluids:A synchrotron XRD and EXAFS investigation. Journal of Magnetism and Magnetic Materials, 300, 213-216(2006)
Department of Physics, University of Agriculture, 38000 - Faisalabad, Pakistan
School of Physics, Universiti Sains Malaysia (USM), 11800-Penang, Malaysia
School of Chemical Sciences, Universiti Sains Malaysia (USM), 11800-Penang, Malaysia