Temperature Dependence Of Coercive Field Of Znfe 2o 4 Nanoparticles

Structural and magnetic measurements on ZnFe 2O 4 nanoparticles obtained through co-precipitation chemical method are reported. The Rietveld analysis of X-ray patterns reveal that (i) our samples are single phase, and (ii) the average particle size increases with synthesis temperature. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization measurements show that the average blocking temperature increases for increasing mean particle size. Besides, one can observe via magnetization measurements that our particle size distribution also increases as a function of synthesis temperature. Finally, we have observed that the coercive field does not decay with the square root of temperature following the Néel relaxation and the Bean-Livingston approaches. In order to fit our experimental data, we have used a generalized model that proposes a temperature dependence of blocking temperature due to the coexistence of blocked and unblocked particles. This proposed generalized model shows good agreement with our experimental results. © 2012 American Institute of Physics.1115Néel, L., (1949) C. R. Acad. Sci., Paris, 228, p. 664Néel, L., (1949) Ann. Geophys., 5, p. 99Kodama, R.H., Makhlouf, S.A., Berkowitz, A.E., (1997) Phys. Rev. Lett., 78, p. 1393. , 10.1103/PhysRevLett.79.1393Kodama, R.H., Berkowitz, A.E., (1999) Phys. Rev. B, 59, p. 6321. , 10.1103/PhysRevB.59.6321De Biasi, E., Ramos, C.A., Zysler, R.D., Romero, H., (2002) Phys. Rev. B, 72, p. 144416. , 10.1103/PhysRevB.65.144416Nunes, W.C., Folly, W.S.D., Sinnecker, J.P., Novak, M.A., (2004) Phys. Rev. B, 70, p. 14419. , 10.1103/PhysRevB.70.014419Allia, P., (2001) Phys. Rev. B, 64, p. 144420. , Marco Coisson, Paola Tiberto, Franco Vinai, Marcelo Knobel, M. A. Novak, and W. C. Nunes, 10.1103/PhysRevB.64.144420Li, F.S., Wang, L., Wang, J.B., Zhou, Q.G., Zhou, X.Z., Kunkel, H.P., Williams, G.J., (2004) J. Magn. Magn. Mater., 268, p. 332. , 10.1016/S0304-8853(03)00544-4Jayadevan, B., Tohji, K., Nakatsuka, K., Narayanasamy, A., (2000) J. Magn. Magn. Mater., 217, p. 99. , 10.1016/S0304-8853(00)00108-6Rietveld, H.M., (1967) Acta Crystallogr., 22, p. 151. , 10.1107/S0365110X67000234Young, R.A., Sakthivel, A., Moss, T.S., Paiva-Santos, C.O., (1995) J. Appl. Crystallogr., 28, p. 366. , 10.1107/S0021889895002160Zhao, N.N., (2008) Langmuir, 24, p. 991. , 10.1021/la702848xLim, B., (2009) Adv. Funct. Mater., 19, p. 189. , 10.1002/adfm.200801439Zysler, R.D., Fiorani, D., Testa, A.M., (2001) J. Magn. Magn. Mater., 244, p. 5. , 10.1016/S0304-8853(00)01328-7Zysler, R.D., (2006) Physica B, 384, p. 277. , 10.1016/j.physb.2006.06.010Wu, J.J., (2006) J. Phys. Chem. B, 110, p. 18108. , 10.1021/jp0644661Salgueirino-Maceira, V., Spasova, M., Farle, M., (2005) Adv. Funct. Mater., 15, p. 1036. , 10.1002/adfm.200400469Caruso, F., Spasova, M., Saigueirino-Maceira, V., Lizmarzan, L.M., (2001) Adv. Mater., 13, p. 1090. , 10.1002/1521-4095(200107)13:14<1090::AID-ADMA1090>3.0.CO;2-HZhu, L.P., Xiao, H.M., Fu, S.Y., (2007) Cryst. Growth Des., 7, p. 177. , 10.1021/cg060454tCangussu, D., Nunes, W.C., Da, H.L., Corra, S., MacEdo, W.A.A., Knobel, M., Alves, O.L., Mazali, I.O., (2009) J. Appl. Phys., 105, p. 013901. , 10.1063/1.3054173Kneller, E.F., Luborsky, F.E., (1963) J. Appl. Phys., 34, p. 656. , 10.1063/1.1729324Pfeiffer, H., (1990) Phys. Status Solidi A, 118, p. 295. , 10.1002/pssa.v118:1Vavassori, P., Angeli, E., Bisero, D., Spizzo, F., Ronconi, F., (2001) Appl. Phys. Lett., 79, p. 2225. , 10.1063/1.1406986Hamdeh, H.H., Ho, J.C., Oliver, S.A., Willey, R.J., Oliveri, G., Busca, G., (1997) J. Appl. Phys., 81, p. 1851. , 10.1063/1.364068Dormann, J.L., Fiorani, D., Tronc, E., (1999) J. Magn. Magn. Mater., 202, p. 251. , 10.1016/S0304-8853(98)00627-1Dormann, J.L., Fiorani, D., Tronc, E., (1997) Adv. Chem. Phys., 98, p. 283. , 10.1002/SERIES2007Winkler, E., Zysler, R.D., Vasquez Mansilla, M., Fiorani, D., (2005) Phys. Rev. B, 72, p. 132409. , 10.1103/PhysRevB.72.132409Zysler, R.D., Ramos, C.A., De Biasi, E., Romero, H., Ortega, A., Fiorani, D., (2000) J. Magn. Magn. Mater., 221, p. 37. , 10.1016/S0304-8853(00)00368-1De Biasi, E., Ramos, C.A., Zysler, R.D., (2003) J. Magn. Magn. Mater., 262, p. 235. , 10.1016/S0304-8853(02)01496-8Tronc, E., (2003) J. Magn. Magn. Mater., 262, p. 6. , 10.1016/S0304-8853(03)00011-8Shim, J.H., Lee, S., Hye Park, J., Han, S., Jeong, Y.H., Whan Cho, Y., (2006) Phys. Rev. B, 73, p. 064404. , 10.1103/PhysRevB.73.064404Hofmann, M., Campbell, S.J., Ehrhardt, H., Feyerherm, R., (2004) J. Mater. Sci., 39, p. 5057. , 10.1023/B:JMSC.0000039185.80910.5