Effect of Co substitution on the structural, electrical, and magnetic properties of Bi_0.9La_0.1FeO₃ by sol-gel synthesis

Abstract

Cobalt (Co)-doped Bi_0.9La_0.1FeO₃ multiferroics were synthesized by a sol-gel method based on the autocombustion technique. As-synthesized powder was examined using various characterization techniques to explore the effect of Co substitution on the properties of Bi_0.9La_0.1FeO₃. X-ray diffraction reveals that Co-doped Bi_0.9La_0.1FeO₃ preserves the perovskite-type rhombohedral structure of BiFeO₃, and the composition without Co preserves the original structure of the phase; however, a second-phase Bi₂Fe₄O₉ has been identified in all other compositions. Surface morphological studies were performed by scanning electron microscopy. Temperature-dependent resistivity of the samples reveals the characteristic insulating behavior of the multiferroic material. The resistivity is found to decrease with the increase both in temperature and Co content. Room temperature frequency-dependent dielectric measurements were also reported. Magnetic measurements show the enhancement in magnetization with the increase in Co content.

Keywords

multiferroics / cobalt / doping / microstructure / electric properties / magnetic properties / sol-gel process

References

[1] Wang K.F., Liu J.M., Ren Z.F. Multiferroicity: the coupling between magnetic and polarization orders. Adv. Phys., 2009, 58(4): 321.

[2] Izyumskaya N., Alivov Ya., Morkoç H. Oxides, oxides, and more oxides: high-κ oxides, ferroelectrics, ferromagnetics, and multiferroics. Crit. Rev. Solid State Mater. Sci., 2009, 34(3–4): 89.

[3] M. Fechner, I.V. Maznichenko, S. Ostanin, A. Emst, J. Henk, P. Bruno, and I. Mertig, Magnetic phase transition in two-phase multiferroics predicted from first principles, Phys. Rev. B, 78(2008), No. 21, article No. 212406.

[4] Lim S.H., Murakami M., Lofland S.E., Zambano A.J., Riba L.G.S., Takeuchi I. Exchange bias in thin-film (Co/Pt)₃/Cr₂O₃ multilayers. J. Magn. Magn. Mater., 2009, 321(13): 1955.

[5] Shtrikman S., Treves D. Observation of the magnetoelectric effect in Cr₂O₃ powders. Phys. Rev., 1963, 130(3): 986.

[6] Fiebig M. Revival of the magnetoelectric effect. J. Phys. D, 2005, 38(8): R123.

[7] Tokura Y. Multiferroics-toward strong coupling between magnetization and polarization in a solid. J. Magn. Magn. Mater., 2007, 310(2): 1145.

[8] Wang J., Neaton J.B., Nagarajan V., Liu B., Vaithyanathan V., Waghmare U.V., Zheng H., Rabe K.M., Wuttig M., Ramesh R., Ogale S.B., Viehland D., Schlom D.G., Spaldin N.A. Epitaxial BiFeO₃ multiferroic thin film heterostructures. Science, 2003, 299(5613): 1719.

[9] J. Wang, M.Y. Li, X.L. Liu, L. Pei, J. Liu, B.F. Yu, and X.Z. Zhao, Synthesis and multiferroic properties of BiFeO₃ nanotubes, Chin. Phys. Lett., 26(2009), No. 11, article No. 117301.

[10] Troyanchuk I.O., Tereshko N.V., Chobot A.N., Bushinsky M.V., Bärner K. Weak ferromagnetism in BiFeO₃ doped with titanium. Phys. B, 2009, 404(21): 4185.

[11] L.W. Martin, S.P. Crane, Y.H. Chu, M.B. Holcomb, M. Gajek, M. Huijben, C.H. Yang, N. Balke, and R. Ramesh, Multiferroics and magnetoelectrics: thin films and nanostructures, J. Phys. Condens. Matter, 20(2008), No. 43, article No. 434220.

[12] Wei J., Xue D.S., Wu C.F., Li Z.X. Enhanced ferromagnetic properties of multiferroic Bi_1−xSr_xMn_0.2Fe_0.8O₃ synthesized by sol-gel process. J. Alloys Compd., 2008, 453(1–2): 20.

[13] Yu X.L., An X.Q. Enhanced magnetic and optical properties of pure and (Mn, Sr) doped BiFeO₃ nanocrystals. Solid State Commun., 2009, 149(17–18): 711.

[14] Singh P., Park Y.A., Sung K.D., Hur N., Jung J.H., Noh W.S., Kim J.Y., Yoon J., Jo Y. Magnetic and ferroelectric properties of epitaxial Sr-doped BiFeO₃ thin films. Solid State Commun., 2010, 150(9–10): 431.

[15] S.R. Das, R.N. Choudhary, P. Bhattacharya, R.S. Katiyar, P. Dutta, A. Manivannan, and M.S. Seehra, Structural and multiferroic properties of La-modified BiFeO₃ ceramics, J. Appl. Phys., 101(2007), No. 3, article No. 034104.

[16] S.T. Zhang, Y. Zhang, M.H. Lu, C.L. Du, Y.F. Chen, Z.G. Liu, Y.Y. Zhu, X.Q. Pan, and N.B. Ming, Substitutioninduced phase transition and enhanced multiferroic properties of Bi_1−xLa_xFeO₃ ceramics, Appl. Phys. Lett., 88(2006), No. 16, article No. 162901.

[17] Al-Haj M. X-ray diffraction and magnetization studies of BiFeO₃ multiferroic compounds substituted by Sm³⁺, Gd³⁺, Ca²⁺. Cryst. Res. Technol., 2010, 45(1): 89.

[18] Jia D.C., Xu J.H., Wang W., Ke H., Zhou Y. Structure and multiferroic properties of BiFeO₃ powders. J. Eur. Ceram. Soc., 2009, 29(14): 3099.

[19] Mazumder R., Sen A. Effect of Pb-doping on dielectric properties of BiFeO₃ ceramics. J. Alloys Compd., 2009, 475(1–2): 577.

[20] P. Kharel, S. Talebi, B. Ramachandran, A. Dixit, M.B. Sahana, C. Sudakar, R. Naik, M.S.R. Rao, G. Lawes, and V.M. Naik, Structural, magnetic, and electrical studies on polycrystalline transition-metal-doped BiFeO3thin films, J. Phys. Condens. Matter, 21(2009), No. 3, art. No. 036001.

[21] Zhou B., Zhang Y.W., Liao C.S., Yan C.H. Magnetism and phase transition for CoFe_2−xMn_xO₄nanocrystalline thin films and powders. J. Magn. Magn. Mater., 2002, 247(1): 70.

[22] Smyth C.P. Dielectric Behavior and Structure, 1955, New York, McGraw-Hill, 53.

[23] Gul I.H., Maqsood A. Structural, magnetic and electrical properties of cobalt ferrites prepared by the sol gel route. J. Alloys Compd., 2008, 465(1–2): 227.

[24] Azough F., Freer R., Thrall M., Cernik R., Tuna F., Collison D. Microstructure and properties of Co-, Ni-, Zn-, Nb- and W-modified multiferroic BiFeO3 ceramics. J. Eur. Ceram. Soc., 2010, 30(3): 727.

[25] Kim W.S., Jun Y.K., Kim K.H., Hong S.H. Enhanced magnetization in Co and Ta-substituted BiFeO₃ ceramics. J. Magn. Magn. Mater., 2009, 321(19): 3262.

[26] Kanai T., Ohkoshi S.I., Hashimoto K. Magnetic, electric, and optical functionalities of (PLZT)_x(BiFeO₃)_1−x ferroelectric-ferromagnetic thin films. J. Phys. Chem. Solids, 2003, 64(3): 391.