Dielectric dispersion and antiferromagnetism in BiTbxFe1−xO3 (x=1.0, 0.75)

Bismuth terbium oxide, BiTbO3 (BT) and bismuth terbium iron oxide, BiTb0.75Fe0.25O3 (BTF) are synthesized by the solid-state reaction technique. Rietveld refinement of the room temperature powder X-ray diffraction pattern of both BT and BTF confirms cubic phase with lattice parameter a=5.4451 (2) and 5.4896 (3) Å respectively. Raman spectroscopy studies have been made to investigate vibrational properties for both the samples. The dielectric relaxation behavior of the samples is investigated by alternating current impedance spectroscopy (ACIS) in the frequency range from 42 Hz to 1.10 MHz and in the temperature range from 303 to 673 K. The complex impedance plane plots and ac conductivity spectra reveal the presence of grain, grain-boundary and electrode effect in BT. Both BT and BTF are antiferromagnetic in nature with Néel temperature of 33.8 and 51.9 K respectively.