CERAMICS INTERNATIONAL Available online at www.sciencedirect.com Ceramics International 39 (2013) S249–S252 Investigation on ferromagnetic and ferroelectric properties of (La, K)-doped BiFeO 3 –BaTiO 3 solid solution Anurak Prasatkhetragarn a,n , Pantip Muangkonkad a , Parichart Aommongkol a , Pongsakorn Jantaratana b , Naratip Vittayakorn c , Rattikorn Yimnirun d a Department of Materials Science, School of Science, University of Phayao, Phayao 56000 , Thailand b Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand c Department of Chemistry, Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand d School of Physics, Institute of Science, Suranaree University of Technology, and Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima 30000, Thailand Available online 24 October 2012 Abstract Multiferroic materials of BiFeO 3 –BaTiO 3 solid solution have been fabricated in order to improve ferromagnetic and ferroelectric properties. The effects of La (1 mol%) and K (varied from 0.5–5 mol%) doped 0.75BiFeO 3 –0.25BaTiO 3 on phase formation, ferromagnetic and ferroelectric properties have been investigated and discussed. The rhombohedral perovskite phase of specimens was characterized by XRD technique. Fracture morphology reveals the grain growth characteristics with increasing K content. (La, K)-doped 0.75BiFeO 3 –0.25BaTiO 3 with La ¼ 1 mol% and K¼ 3 mol% exhibits the highest remnant polarization and remnant magnetization. & 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: Ferroelectric properties; Magnetic properties; Multiferroic 1. Introduction BiFeO 3 -based compounds have received considerable attention and have been studied extensively, because they exhibit both ferroelectric and ferromagnetic characteristics; thus they provide the possibility of applications in devices such as nonvolatile memory, sensors, waveguides, modu- lators, switches, phase invertors, rectifiers, etc. [1–4]. Bulk BiFeO 3 ceramic possesses a ferroelectric Curie temperature (T C ) of 1103 K (830 1C) and an antiferromagnet Ne´el temperature (T N ) of 643 K (370 1C) [3]. However, bulk BiFeO 3 ceramic has some disadvantages such as it is difficult to prepare pure single phase BiFeO 3 , and BiFeO 3 -based materials have a low electrical resistivity. The relatively high conductivity of BiFeO 3 is believed to be due to the degradation of Fe 3 þ species to Fe 2 þ species, thus creating oxygen vacancies for charge compensation. These problems have prevented the material’s practical applications as piezoelectric or magnetoelectric functional components [3]. Processing BiFeO 3 with other perovskite structured materials, such as BaTiO 3 (BT) and PbTiO 3 , would prevent the formation of secondary phases [5–7] and enhance the electrical resistivity. In addition, Ti substitu- tion at the Fe sites can increase the magnetization of the novel compounds [7]. Prior research, S.O. Leontsev and R.E. Eitel have been prepared on Mn-doped (1  x)BiFeO 3 –xBaTiO 3 , it was found that ceramics with 25 mol% BT showed the highest value of dielectric and ferroelectric properties. It is expected that with continuous processing improvements and composition modification, the 0.75BiFeO 3 –0.25BaTiO 3 (0.75BF–0.25BT) system will form the basis of an important family of high-performance lead free piezoelectric ceramics [8]. Although the perovskite structure of these solid solu- tions has been found to be stable at room temperature, their ferromagnetism is still weak. To improve the ferroelectric and ferromagnetic properties, (La, K)-doped www.elsevier.com/locate/ceramint 0272-8842/$ - see front matter & 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. http://dx.doi.org/10.1016/j.ceramint.2012.10.071 n Corresponding author. Tel.: þ 6654 466666; fax: þ6654 466664. E-mail addresses: prasatkhetragarn@yahoo.com (A. Prasatkhetragarn), rattikorn@g.sut.ac.th (R. Yimnirun).