CERAMICS INTERNATIONAL Available online at www.sciencedirect.com Ceramics International 41 (2015) 2389–2398 Influence of Eu substitution on structural, magnetic, optical and dielectric properties of BiFeO 3 multiferroic ceramics Prakash Chandra Sati a , Manoj Kumar a,n , Sandeep Chhoker a , Mukesh Jewariya b a Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida 201307, India b National Physical Laboratory (CSIR), Dr. K.S. Krishnan Marg, New Delhi 110012, India Received 1 September 2014; received in revised form 9 October 2014; accepted 9 October 2014 Available online 16 October 2014 Abstract Eu substituted BiFeO 3 (Bi 1 x Eu x FeO 3 ; x ¼ 0–0.15) polycrystalline ceramics were synthesized by a solid state reaction method. Rietveld refinement of X-ray diffraction patterns reveals that samples crystallize in R3c structure for x r0.10 and (R3c þ Pn2 1 a) phases coexist for x Z0.12–0.15. The magnetic measurements show weak ferromagnetic nature of Eu substituted BiFeO 3 samples due to ferromagnetic coupling between Eu 3 þ and Fe 3 þ ions. The remnant magnetization is found to increase from 0.0003 emu/g for x ¼ 0.00 to 0.087 emu/g for x ¼ 0.15. The gradual change in line shape of electron spin resonance spectra has been attributed to local distortion induced by Eu substitution. UV–visible absorption spectra in the spectral range 1.12–3.5 eV were dominated by two charge transfer transitions and two doubly degenerate d–d transitions. The optical band gap is found to decrease from 2.25 to 2.16 eV with increasing Eu concentration. Improved dielectric properties with enhancement in frequency independent region of dielectric constant and loss have been observed. & 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: B. X-ray methods; C. Dielectric properties; C. Magnetic properties; C. Optical properties 1. Introduction Magnetoelectric multiferroics, combining ferroelectric and magnetic properties, show considerable promise for applications in several devices such as electric-field-controlled ferromagnetic resonance devices, transducers with magnetically modulated piezoelectricity, and multiple-state memory elements [1,2]. The magnetoelectric coupling between magnetic and electrical orders in these multiferroics has enabled us to control magnetic polari- zation by applying electric field and vice versa [3]. Amongst naturally occurring multiferroics, BiFeO 3 (BFO) has been considered as a unique material for the development of multi- functional devices because of its characteristic ferroelectric, magnetic, piezoelectric and optical properties. It includes a high ferroelectric Curie temperature (T C  1100 K), high antiferro- magnetic Néel temperature of (T N  650 K), lead-free piezo- electricity and large flexibility in the wavelength of visible light region [4,5]. These features make BiFeO 3 particularly applicable in the fields of ferroelectrics, magnetics, piezoelectrics, and optics; in addition, cross correlation of these properties can be expected above room temperature (RT) [6]. BiFeO 3 has a pero- vskite-type crystal structure that is rhombohedrally distorted in the [111] direction and crystallizes in the space group R3c [7]. Its ferroelectric order originates from the stereochemical activity of the Bi lone electron pair [8,9]. As the A-site Bi 3 þ ion of BiFeO 3 shows a valence electron configuration of 6s 2 6p 0 the lone 6s 2 electrons of Bi 3 þ ion hybridize with both the empty 6p 0 orbits of Bi 3 þ ion and the 2p 6 electrons of O 2  ion to form Bi–O covalent bonds, leading to a structural distortion and hence ferroelectric order [9,10]. This is characterized by the second- order Jahn–Teller effect and is referred to as the stereochemical activity of the Bi lone electron pair. Even though BFO exhibits ferroelectric properties, its applications are limited due to excess leakage current [11]. In term of magnetic properties, BFO is antiferromagnetic with a G-type spin configuration [7,12] i.e., nearest neighbour Fe moments are aligned antiparallel to each other. But the Dzyaloshinskii–Moriya (DM) interaction www.elsevier.com/locate/ceramint http://dx.doi.org/10.1016/j.ceramint.2014.10.053 0272-8842/& 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved. n Corresponding author. E-mail address: manoj.chauhan@jiit.ac.in (M. Kumar).