Structural, magnetic, dielectric, ac-conductivity and photocatalytic properties of Gd doped BiFeO3 nanoparticles.

Abstract

In this paper, a series of Bi1-xGdxFeO3 (x = 0, 0.05, 0.1, 0.15, 0.2) samples synthesized by combustion are investigated. The effect of Gd dopant on the crystal structure, morphology, magnetic, electrical and photocatalytic properties of nanoparticles is 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 eV–1.94 eV, which implies possible applications in the visible spectrum. The samples demonstrated ferromagnetic behavior with the highest magnetization values for Bi0.9Gd0.1FeO3. Three anomalies were found in the temperature dependences of the permittivity ε'(T) in the temperature range of ~ 250 °C, ~ 310 °C and TN. The absence of an unambiguous dependence of the dielectric characteristics with increasing Gd concentration was found. The frequency dependence of the conductivity σac(ω) at different temperatures was analyzed based on the universal Jonscher power law σ ∼ ωs. The frequency dependence of the conductivity σac was interpreted within the framework of the correlated barrier jumping (CBH) model. The plots of lnσac 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.