Arab J Sci Eng (2015) 40:2079–2084 DOI 10.1007/s13369-015-1668-z RESEARCH ARTICLE - PHYSICS Influence of (La, Cu) Doping on the Room Temperature Multiferroic Properties of BiFeO 3 Ceramics A. Sathiya Priya 1 · I. B. Shameem Banu 1 · Murthy Chavali 2 Received: 5 January 2015 / Accepted: 13 April 2015 / Published online: 24 April 2015 © King Fahd University of Petroleum & Minerals 2015 Abstract A series of Bi 1−x La x Fe 0.98 Cu 0.02 O 3 (x = 0.01, 0.03 and 0.05) ceramics were synthesized by sol–gel method. The prepared ceramics were characterized by X-ray diffrac- tometer (XRD), vibrating sample magnetometer (VSM) and dielectric measurement. XRD patterns reveal that Bi 1−x La x Fe 0.98 Cu 0.02 O 3 (x = 0.01, 0.03 and 0.05) ceramics crys- tallize in single-phase rhombohedral structure with R3c space group without distortion, and the average crystallite size was in the range of 31–92 nm. VSM exhibited a weak ferro- magnetism for La- and Cu-co-doped BiFeO 3 ceramics. The squareness ratio of the hysteresis loop decreases as La con- centration increases in Bi 1−x La x Fe 0.98 Cu 0.02 O 3 . However, these materials show improved dielectric properties com- pared to undoped BiFeO 3 ceramic. Keywords Sol–gel · BiFeO 3 · VSM · Squareness ratio · Dielectric constant · Dielectric loss 1 Introduction Multiferroic materials are one of the fascinating materials which exhibit two or more ferroic properties simultaneously [1–4]. The magnetoelectric coupling which is the occurrence of polarization on applying a magnetic field or occurrence of magnetization on applying a electric field is the special fea- ture of these materials [5]. Multiferroic materials are used B A. Sathiya Priya priyasathiya8@gmail.com 1 Department of Physics, B. S. Abdur Rahman University, Chennai, Tamil Nadu, India 2 Division of Chemistry, Department of Science and Humanities, Vignan’s University, Guntur, Andhra Pradesh, India in spintronics, sensors and multifunctional devices [6, 7]. BiFeO 3 (BFO) is one of the well-known multiferroic materi- als which have a magnetoelectric effect (ME) at room temper- ature. It has a rhombohedrally distorted perovskite structure with space group R3c. In BiFeO 3 , Bi 3+ ions have lone pair electrons and are responsible for the ferroelectric property. Fe 3+ ions have partially filled inner shells and are responsi- ble for ferromagnetic property. BFO has ferroelectric curie temperature of (T c ) ∼850 ◦ C and Neel’s temperature of (T N ) about 370 ◦ C[8–10]. BFO has some drawbacks such as large leakage current. Superimposed incommensurate cycloid spin structure cancels out its macroscopic magnetization, and so it exhibits weak antiferromagnetism at room temperature and shows spatially non-uniform magnetic structure. To suppress the spiral spin structure so as to enhance the magnetic mo- ment and to reduce the leakage current, one of the effective methods is to chemically modify BFO by doping. Several studies reported that when rare earth elements such as Dy, La, Nd and Sm are doped in Bi site and transition metals such as Cu, Mn, Cr are doped in Fe site, magnetic and electrical properties of BFO can be improved [11–14]. A few reports on the La-doped BFO have revealed the improvement in the magnetic properties of the doped BFO. Chaudhuri and Mandal [15] reported on Bi 1−x La x FeO 3 (x = 0, 0.05, 0.1 and 0.15) synthesized by hydrothermal method and demonstrated the improved magnetic and electric prop- erties. Yan et al. [16] reported that the saturation magnetiza- tion of Bi 1−x La x FeO 3 (x = 0, 0.05 and 0.1) increases with increase in La concentration. Yang et al. [17] reported on Bi 0.9−x La 0.1 Ca x FeO 3 (BLCFO x ) (x = 0, 0.10, 0.13, 0.17 and 0.20) nanoparticles prepared by sol–gel method. The concentration of x ≤ 0.17 exhibited the antiferromagnetic behavior. They observed a typical increase in magnetiza- tion with the reduction in particle size. With increase in the concentration, remnant magnetization and coercive mag- 123