Synthesis And Ageing Effect In Feo Nanoparticles: Transformation To Core-shell Feo/fe3o4 And Their Magnetic Characterization

This paper reports the magnetic properties of partially oxidized FeO nanoparticles (NPs) prepared using thermal decomposition of iron acetylacetonate at high temperature. X-ray diffraction (XRD) analysis confirmed that the resulting NPs comprise a mixture of wüstite and magnetite phases, which are subsequently confirmed using high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) pattern. Magnetic properties were investigated using vibrating sample magnetometer (VSM), which exhibit superparamagnetic (SPM) behavior at room temperature. Alternatively, below 200 K, a large exchange bias field has been observed in field cooled mode whose magnitude increases with the decrease in measuring temperature attaining a maximum value of ∼2.3 kOe at 2 K accompanied by coercivity enhancement (∼3.4 kOe) and high field of irreversibility (>50 kOe). The results are discussed taking into account the role of interface exchange coupling on the macroscopic magnetic properties of the nanoparticles. © 2011 Elsevier B.V. All rights reserved.5092264146417Zeng, B.Z., Sun, S., (2008) Adv. Funct. Mater., 18, p. 391Hou, Y., Xu, Z., Sun, S., (2007) Angew. Chem. Int. Ed., 46, p. 6329Chen, C.J., Chiang, R.K., Lai, H.Y., Lin, C.R., (2010) J. Phys. Chem. C, 114, p. 4258Meiklejohn, W.H., Bean, C.P., (1957) Phys. Rev., 105, p. 904Chappert, C., Fert, A., Van Dau, F.N., (1999) Nat. Mater., 200, p. 552Skumryev, V., Stoyanov, S., Zhang, Y., Hadjipanyis, G., Givord, D., Nogues, J., (2003) Nature (London), 423, p. 850Ong, Q.K., Wei, A., Lin, X.-M., (2009) Phys. Rev. B, 80, p. 134418Guo, S., Liu, W., Meng, M., Liu, X.H., Gong, W.J., Han, Z., Zhang, Z.D., (2010) J. Alloys Compd., 497, p. 10Hai, H.T., Yang, H.T., Kura, H., Hasegawa, D., Ogata, Y., Takahashi, M., Ogawa, T., (2010) J. Colloid Interface Sci., 346, p. 37Tsuzuki, T., Schäffel, F., Muroi, M., McCormick, P.G., (2011) J. Alloys Compd., 509, p. 5420Fernández-García, M.P., J. Alloys Compd, , doi:10.1016/j.jallcom.2010.12.206Karthik, K., Selvan, G.K., Kanagaraj, M., Arumugam, S., Victor Jaya, N., (2011) J. Alloys Compd., 509, p. 181Nogués, J., Schuller, I.K., (1999) J. Magn. Magn. Mater., 192, p. 203Berkowitz, A.E., Takano, K., (1999) J. Magn. Magn. Mater., 200, p. 552Stamps, R.L., (2000) J. Phys. D: Appl. Phys., 33, p. 247Nogués, J., Sort, J., Langlais, V., Doppiu, S., Dieny, B., Munoz, J.S., Surinach, S., Zhang, Y., (2005) Int. J. Nanotechnol., 2, p. 23Bobo, J.F., Gabillet, L., Bibes, M., (2004) J. Phys.: Condens. Matter, 16, p. 471Zheng, R.K., Wen, G.H., Fung, K.K., Zhang, X.X., (2004) J. Appl. Phys., 95, p. 5244Bianco, L.D., Fiorani, D., Testa, A.M., Bonetti, E., Signorini, L., (2004) Phys. Rev. B, 70, p. 052401Kavich, D.W., Dickerson, J.H., Mahajan, S.V., Hasan, S.A., Park, J.H., (2008) Phys. Rev. B, 78, p. 174414Sheera, M.S., Roy, P., Manivannan, M., (2000) Mater. Res. Soc. Symp. Proc., 581, p. 511Kodama, R.H., Berkowitz, A.E., McNiff Jr., E.J., Foner, S., (1997) J. Appl. Phys., 81, p. 5552Lima Jr., E., Vargas, J.M., Rochenberg, H.R., Zysler, R.D., (2008) J. Nanosci. Nanotechnol., 8, p. 5913Shavel, A., Gonzalez, B.R., Spasova, M., Spasova, M., Farle, M., Liz-Marzan, L.M., (2007) Adv. Mater., 17, p. 3870Prozorov, R., Prozorov, T., Mallapragada, S.K., Narasimhan, B., Williams, T.J., Bazylinski, D.A., (2007) Phys. Rev. B, 76, p. 054406Garcia, J., Subias, G., (2004) J. Phys.: Condens. Matter, 16, p. 145Walz, F., (2002) J. Phys.: Condens. Matter, 14, p. 285Verwey, E.J., (1999) Nature, 144, p. 32