Influence of Ni doping on the structural, ferroelectric, magnetic and optical properties of $$\hbox {Bi}_{0.85}\hbox {Nd}_{0.15}\hbox {Fe}_{1-x}\hbox {Ni}_{x}\hbox {O}_{3}$$ thin films

Abstract

\(\hbox {Bi}_{0.85}\hbox {Nd}_{0.15}\hbox {Fe}_{1-x}\hbox {Ni}_{x}\hbox {O}_{3}\) (\(x = 0.025\)–0.125) thin films were synthesized by applying a sol–gel method on fluorine-doped tin oxide substrates. The influence of Ni doping concentration on the structure, leakage current, ferroelectric, magnetic and optical properties of \(\hbox {Bi}_{0.85}\hbox {Nd}_{0.15}\hbox {Fe}_{1-x}\hbox {Ni}_{x}\hbox {O}_{3}\) thin films was investigated. \(\hbox {Bi}_{0.85}\hbox {Nd}_{0.15}\hbox {Fe}_{1-x}\hbox {Ni}_{x}\hbox {O}_{3}\) thin films are polycrystalline films that present a single perovskite structure without any impurity phase when the Ni doping concentration is below 0.1 and present a \(\hbox {Bi}_{2}\hbox {Fe}_{4}\hbox {O}_{9}\) phase when the Ni doping concentration is above 0.1. The grain size of the films and their holes gradually decrease with an increase in the Ni doping amount. The saturation magnetization of \(\hbox {Bi}_{0.85}\hbox {Nd}_{0.15}\hbox {Fe}_{1-x}\hbox {Ni}_{x}\hbox {O}_{3}\) thin films increases with Ni content. However, appropriate Ni doping concentration can decrease the leakage current and enhance the ferroelectric polarization and optical transmittance of the films. Meanwhile, the absorption edge has a slight red shift. \(\hbox {Bi}_{0.85}\hbox {Nd}_{0.15}\hbox {Fe}_{1-x}\hbox {Ni}_{x}\hbox {O}_{3}\) thin films possess better combination properties at a leakage current density of \(4.27 \times \,10^{-9}\hbox { A cm}^{-2}\), ferroelectric polarization of \(28.58\, \upmu \hbox {C cm}^{-2}\), saturation magnetization of \(2.08\hbox { emu cm}^{-3}\) and transmittance of over 85% when the Ni doping concentration, x is 0.05.