Ac-conductivity and structural, magnetic, dielectric, and photocatalytic properties of Gd doped BiFeO3 nanoparticles

Abstract

In this study, a series of Bi_1−xGd_xFeO₃ (x = 0, 0.05, 0.1, 0.15, and 0.2) samples synthesized by a combustion method were investigated. The effect of Gd dopant on the crystal structure, morphology, magnetic, electrical and photocatalytic properties of nanoparticles was studied. X-ray diffraction showed that the samples with x = 0.1 and 0.15 contain two-phase systems R3c + Pbam and R3c + Pnma, respectively. UV-vis spectroscopy showed that the optical band gap lies in the range of 2.08–1.94 eV, which implies possible applications in the visible spectrum. The samples demonstrated ferromagnetic behavior with the highest magnetization values for Bi_0.9Gd_0.1FeO₃. Three anomalies were found in the temperature dependences of the permittivity ε′(T) in the temperature range of ∼250 °C to ∼310 °C and T_N. The absence of an unambiguous dependence of the dielectric characteristics with increasing Gd concentration was observed. The frequency dependence of the conductivity σ_ac(ω) at different temperatures was analyzed based on the universal Jonscher's power law σ ∼ ω^s. The frequency dependence of the conductivity σ_ac was interpreted within the framework of the correlated barrier jumping (CBH) model. The plots of ln σ_ac vs. 10³/T revealed the presence of various thermally activated conductivity mechanisms. A positive effect of the Gd dopant on the improvement of the photocatalytic properties of BiFeO₃ was established.