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Microstructural Evolution of Nanocrystalline Magnetite Synthesized by Electrocoagulation

  • Ying-Chieh Weng (a1), I.A. Rusakova (a2), Andrei Baikalov (a2), J.W. Chen (a3) and Nae-Lih Wu (a1)...


Nanocrystalline magnetite powders were synthesized by an electrocoagulation technique, in which an electric current was passed across two plate electrodes of carbon steel immersed in NaCl(aq) electrolyte, and the microstructure of the oxide powder was found to evolve in roughly three stages. The first stage involves formation and growth of severely defective colloidal crystallites. This is followed by agglomeration among the oxide crystallites to form mesoporous agglomerates containing predominantly inter-crystallite pores, and the average crystallite size was found to reach a plateau. Finally, coarsening of the crystallites within the agglomerates leads to another rapid increase in crystallite size and reduction in pore opening. The synthesized powders typically showed a saturation magnetization of ∼75 emu/g and a coercivity Hc of ∼118 Oe. A mechanism involving competition between nucleation and growth of free colloids and coarsening of the skeletal framework was proposed to explain the temporary level-off in crystallite size during the synthesis.


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1Bohacek, J., Subrt, J., Hanslik, T. and Tlaskal, J.: Preparing particulate magnetites with pigment properties from suspensions of basic iron(III) sulfates with the structure of Jarosite. J. Mater. Sci. 28, 2827 (1993).
2Comstock, R.L.: Modern magnetic materials in data storage. J. Mater. Sci. Mater. Electron. 13, 509 (2002).
3Wu, K.T., Kuo, P.C., Yao, Y.D. and Tsai, E.H.: Magnetic and optical properties of Fe3O4 nanoparticles ferrofluids prepared by coprecipitation technique. IEEE Trans. Magn. 37(4), 26512653 (2001).
4Shinkai, M.: Functional magnetic particles for medical application. J. Biosci. Bioeng. 94, 606 (2002).
5Perez, J.M., Simeone, F.J., Saeki, Y., Josephson, L. and Weissleder, R.: Viral-induced self-assembly of magnetic nanoparticles allows the detection of viral particles in biological media. J. Am. Chem. Soc. 125, 10192 (2003).
6Beydoun, D., Amal, R., Low, G.K.C., McEvoy, S.: Novel photocatalyst: Titania-coated magnetite. Activity and photodissolution. J. Phys. Chem. B 104, 4387 (2000).
7Kang, Y.S., Risbud, S., Rabolt, J.F. and Stroeve, P.: Synthesis and characterization of nanometer-size Fe3O4 and γ–Fe2O3 particles. Chem. Mater. 8, 2209 (1996).
8Lee, H.S., Lee, W.C. and Furubayashi, T.: A comparison of coprecipitation with microemulsion methods in the preparation of magnetite. J. Appl. Phys. 85, 5231 (1999).
9Diamandescu, L., Mihaila-Tarabasanu, D., Teodorescu, V. and Popescu-Pogrion, N.: Hydrothermal synthesis and structural characterization of some substituted magnetites. Mater. Lett. 37, 340 (1998).
10Li, Y., Liao, H., Qian, Y.: Hydrothermal synthesis of ultrafine α–Fe2O3 and Fe3O4 powders. Mater. Res. Bull. 33, 841 (1998).
11Bae, D.S., Han, K.S., Cho, S.B. and Choi, S.H.: Synthesis of ultrafine Fe3O4 powder by glycothermal process. Mater. Lett. 37, 255 (1998).
12Sun, S. and Zeng, H.: Size-controlled synthesis of magnetite nanoparticles. J. Am. Chem. Soc. 124, 8204 (2002).
13Khollam, Y.B., Dhage, S.R., Potdar, H.S., Deshpande, S.B., Bakare, P.P., Kulkarni, S.D. and Date, S.K.: Microwave hydrothermal preparation of submicron-sized spherical magnetite (Fe3O4) powders. Mater. Lett. 56, 571 (2002).
14Dhage, S.R., Khollam, Y.B., Potdar, H.S., Deshpande, S.B., Bakare, P.P., Sainkar, S.R. and Date, S.K.: Effect of variation of molar ratio (pH) on the crystallization of iron oxide phases in microwave hydrothermal synthesis. Mater. Lett. 57, 457 (2002).
15Tsouris, C., Depaoli, D.W. and Shor, J.T. Method and apparatus to electrolytically produce high-purity magnetite particles, U.S. Patent No. 6 179 987(2001).
16Tsouris, C., DePaoli, D.W., Shor, J.T., Hu, M.Z.C. and Ying, T.Y.: Electrocoagulation for magnetic seeding of colloidal particles. Colloids Surf. A 177, 223 (2001).
17Ying, T.Y., Yiacoumi, S. and C., Tsouris: An electrocoagulation method for the formation of magnetite particles. J. Disp. Sci. Technol. 23, 569 (2002).
18Wu, N.L., Wang, S.Y., Han, C.Y., Wu, D.S. and Shiue, L.R.: Electrochemical capacitor of magnetite in aqueous electrolytes. J. Power Sources 113, 173 (2003).
19Jones, F.W.: The measurement of particle size by the x-ray method. Proc. Roy. Soc. (London) 166A, 16 (1938).
20Lee Pan, R. and Banfield, J.F.: Morphology development and crystal growth in nanocrystalline aggregates under hydrothermal conditions: Insight from titania. Geochimi. Cosmochimi. Acta 63, 1549 (1999).
21Yeadon, Y., Ghaly, M., Yang, J.C., Averback, R.S. and Gibson, J.M.: Contact epitaxy observed in supported nanoparticles. Appl. Phys. Lett. 73, 3208 (1998).
22Banfield, J.F., Welch, S.A., Zhang, H., Ebert, T.T. and Penn, R.L.: Aggregation-based crystal growth and microstructure development in natural iron oxyhydroxide biomineralization products. Science 289, 751 (2000).


Microstructural Evolution of Nanocrystalline Magnetite Synthesized by Electrocoagulation

  • Ying-Chieh Weng (a1), I.A. Rusakova (a2), Andrei Baikalov (a2), J.W. Chen (a3) and Nae-Lih Wu (a1)...


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