Effect of Gd-substitution on the ferroelectric and magnetic properties of BiFeO₃ processed by high-energy ball milling

Multiferroic BiFeO₃ was synthesized by means of high-energy ball milling (HEBM) followed by thermal annealing at various temperatures and the effect of Gd³⁺ substitution (x=0.0–0.20) at Bi³⁺ site was investigated in this study. It is found that the Gd-substitution tends to decrease the impurity phases and the crystallization of single phase BiFeO₃ is observed at x=0.1. Scanning electron micrograph of Bi_1−xGd_xFeO₃ sintered sample indicated a decrease in particle size and change in shape with increasing x. For all the studied samples, the measured dielectric constant values tend to increase from 110 (x=0.0) to 250 (x=0.10). The dielectric loss is found to be more for the pure BiFeO₃ as compared to the Bi_1−xGd_xFeO₃. Ferroelectric loops show a maximum polarization of 1.63 μC/cm² for the Bi_0.9Gd_0.1FeO₃. Magnetization (M) versus magnetic field (H) hysteresis loops at 300 K BiFeO₃ and Bi_0.9Gd_0.1FeO₃ demonstrated non-saturated loops, suggesting the antiferromagnetic nature of the samples. The M–H behavior of the Bi_1−xGd_xFeO₃ at 300 K shows the antiferromagnetic nature of the samples. The estimated magnetization value at 10 kOe for the Bi_0.9Gd_0.1FeO₃ sample (0.23 emu/g) is found to be higher than that of the pure BiFeO₃ (0.037 emu/g).