Journal of Alloys and Compounds 504 (2010) 420–426 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom The role of doping on the structural and functional properties of BiFe 1-x Mn x O 3 magnetoelectric ceramics Adelina Ianculescu a , Felicia Prihor Gheorghiu b,∗ , Petronel Postolache b , Ovidiu Oprea a , Liliana Mitoseriu b a Dept. of Science & Engineering of Oxide Materials, Polytechnics University of Bucharest, Romania b Dept. of Physics, Al. I. Cuza University, Bv. Carol I no. 11, Iasi, 700506, Romania article info Article history: Received 17 February 2010 Received in revised form 28 May 2010 Accepted 28 May 2010 Available online 10 June 2010 Keywords: Ceramics Solid state reaction Microstructure Dielectric response abstract BiFeO 3 is one of the few single-phase multiferroics, showing antiferromagnetic and ferroelectric order- ing. Since the dielectric properties in the ceramic state of the pure BiFeO 3 were rather poor and in order to stabilize the perovskite state and to induce ferromagnetism at room temperature, it was adopted the strategy of doping with rare earth or forming solid solutions. Substituting Fe with Mn in BiFeO 3 -based compounds is supposed cause better properties in terms of leakage current density and also to induce changes in the magnetic order of the system. In the present paper, the effect of Mn substitution on the dielectric and magnetic properties of the BiFe 1-x Mn x O 3 ceramics has been studied. Homogeneous sam- ples from microstructural point of view were obtained for all the compositions analyzed. The magnetic properties are strongly affected by the presence of Mn ions. The possible origin of these behavior is discussed in terms of phase purity, grain size and grain boundary phenomena. The extrinsic properties are impossible to be fully controlled by normal ceramic processing. By controlling the extrinsic contri- butions to the dielectric properties, the ceramic system might be a valuable multiferroic material for magnetoelectric applications. At room temperature the ceramic is a multiferroic, since it is ferroelectric and magnetically-ordered. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Multiferroic materials, in which ferroelectricity and mag- netism coexist, attract much attention from both fundamental and practical points of view [1,2]. Although multiferroics are highly exciting materials for potential application, there are few systems which show magnetoelectric (ME) multiferroic behav- ior, due to the apparent opposite requirements concerning the d-orbital occupancy for ferroelectric and magnetic order [3,4]. BiFeO 3 (BFO) is one of the few single-phase multiferroics at room temperature having a distorted perovskite structure with rhombohedral symmetry (space group R3c). It exhibits both ferro- electric properties with a high Curie temperature (T C = 830 ◦ C) and antiferromagnetic order (Néel temperature T N = 370 ◦ C), and also shows a weak ferro/ferri magnetic characteristic in some temper- ature ranges [5]. Although promising for its multiferroic character, only poor dielectric and ferroelectric properties (low values of the polarization and of the dielectric constant) were found at room temperature in the bulk ceramics, mainly due to the semiconduct- ∗ Corresponding author. E-mail address: felicia prihor@stoner.phys.uaic.ro (F.P. Gheorghiu). ing character which does not allow a proper electrical poling and lead to high dielectric losses [4]. In order to improve the electrical properties while preserving the magnetic ordering, several research groups adopted the strat- egy of doping BiFeO 3 with different +3 valence ions on A, B or both A and B sites [6–10]. The doping has resulted in the reduc- tion of the leakage current density and in the improvement of the ferroelectric properties to some extent. Such substitutions were also expected to shift the transition temperature towards the room temperature. According to the Shannon et al. [11], the Mn 3+ (ionic radius = 0.645 Å) ions can occupy the Fe 3+ sites in BiFeO 3 materials, because both ions have the same valence state and similar ionic size to that of Fe 3+ (0.645 Å). Even if there are different oxidation states of Mn (3+, 4+) in Mn-doped BiFeO 3 materials, the ionic radii of the different oxidation states of Mn are comparable to that of Fe 3+ . Con- sequently, the Mn ions can occupy the Fe sites only. Similar types of observations have been reported by Chung et al. [8]. From technological point of view, magnetoelectric multiferroics are wanted to show a kind of magnetic order (ferro- or ferrimag- netic) at room temperature. Due to the cycloidal spin magnetic structure [12] with long wavelength (∼62 nm), a weak ferromag- netism was generally observed in BiFeO 3 at room temperature. In addition, weak ME coupling is often reported. The substitution of Fe with Mn in BiFeO 3 -based compounds is expected to result in better 0925-8388/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2010.05.135