Predicting High Magneto-Electric Coupling in Gd Substituted BiFeO3

Polycrystalline BiFeO3 and Bi0.90R0.10FeO3 (R = La, Nd, Eu, Gd, and Ho) compounds are prepared by solid state synthesis. X-ray diffraction and Raman measurements evidence that La and Nd substitutions retain the rhombohedral R3c crystal structure similar to BiFeO3 whereas a nominal orthorhombic phases are evolved in Eu, Gd, and Ho-substituted compounds. The magnetic measurements at 10 and 300 K clearly indicate that the substitution modifies the spin structure of BiFeO3 and enhances the remanent magnetization M-r and coercive field H-c. The improved magnetic properties are correlated to the tolerance factor t of the compound. The variation of H-c with respect to field at 10 and 300 K illustrates the possibility of high magneto-electric coupling in the Gd substituted compounds. The substitution of rare earth elements results better ferroelectric hysteresis loops due to the reduction of leakage currents. Better and enhanced ferroelectric properties are observed with La substitution. The observed ferroelectric properties are also discussed in terms of tolerance factor. This study is useful to identify the potential rare earth substituent to tune the magnetic and ferroelectric properties of BFO.