Enhanced multiferroism in Gd-doped BiMn2O5 ceramics

Gd doped Bi_1-xGd_xMn₂O₅ (x = 0.00–0.12) ceramics are synthesized via solid state reaction technique and they have been investigated for their structural, morphological, magnetic and electric properties. X-ray diffraction experiments and their corresponding Rietveld refinement confirm that the major phase characteristics of all the compositions are orthorhombic. The morphological studies reveal that the average grain size gradually decreases from $～500\mathrm{nm}$ to $～200\mathrm{nm}$ due to Gd substitution. The temperature dependent zero field cooled (ZFC) and field cooled (FC) magnetization curves demonstrate an antiferromagnetic Néel transition at 42 K. Due to the substitution of 4% Gd, the phase transition remains unaltered, however, both ZFC and FC curves coincide with each other at an applied magnetic field of 500 Oe. The remanent magnetizations and coercive fields are also found to enhance at room temperature due to the substitution of Gd. The polarization vs. electric field hysteresis loops exhibits the ferroelectric behavior of Bi_1-xGd_xMn₂O₅ (x = 0.00–0.12) ceramics at room temperature. Gd substitution also results in enhanced stability of the dielectric constant at wide range of high frequencies with significant suppression of low frequency dispersion particularly for 12% Gd doping. Moreover, a correlation among leakage current, remanent polarization, dielectric constant and microstructure has also been observed while investigating the Gd doped BiMn₂O₅ ceramics.