Effect of holmium oxide on impedance and dielectric behavior of polyaniline–holmium oxide composites

Applying chemical in situ polymerization method, conducting polyaniline–holmium oxide (PANI/Ho₂O₃) composites with varying wt% of Ho₂O₃ in PANI were prepared. Composites were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Room temperature frequency response conductivity and the dielectric studies of the as synthesized composites were investigated in the range 50 to 10⁶ Hz. AC conductivity was found to decrease with the increasing wt% of Ho₂O₃. Further, conductivity of the composites obeyed power law of disordered materials. Cole–Cole plots for each composite, depicted single semicircle inferring that the conduction is due to the hopping of charge carriers. With increasing wt% of Ho₂O₃, dielectric constant and dielectric loss both decreased and at low frequencies, high dielectric constant of the composites, found decreasing with increasing applied frequencies due to Maxwell–Wagner type polarization. Tangent loss plots showed relaxation peaks at the resonant frequency.