The abnormal electrical and optical properties in Na and Ni codoped BiFeO3 nanoparticles

Abstract

Bi 0.97 Na 0.03 Fe 1Àx Ni x O 3 (x ¼ 0, 0.005, 0.01, 0.015) nanoparticles are prepared via a sol-gel method. Weak ferromagnetism and exchange bias phenomenon without field cooling are observed in the samples. The oxygen vacancy concentration and leakage current density are increased with increasing the Ni content. However, with the increase of Ni content, the band gap of Bi 0.97 Na 0.03 Fe 1Àx Ni x O 3 nanoparticles first decreases and then increases. To explain the abnormal phenomenon, the interplay of oxygen vacancy donor and hole acceptor is analyzed and a phenomenological qualitative model based on the electronic energy band is proposed. Additionally, the threshold switching behavior appears in Bi 0.97 Na 0.03 Fe 1Àx Ni x O 3 samples with x ¼ 0.01, 0.015 and the effect is qualitatively explained by introducing a conducting channel model based on the high-density mobile charges.

Enhanced optical and piezoelectric characteristics of transparent Ni-doped BiFeO3 thin films on a glass substrate

“…3,4 The optical band gaps of the lms tend to decrease with Ni doping: E g ¼ 2.80 and 2.79 eV are calculated for the samples with 0.5 and 1.0 mol% Ni, respectively. It is plausible that the high concentration of Ni increases the concentration of oxygen-related defect states in the valence-band edge, thereby widening the valence band and thus contributing to narrowing the band gap, 24,26 as suggested by the XPS result shown in Fig. 3(d).…”

“…This result indicates that Ni substitution intensies the oxygenrelated defects, which is consistent with what is observed in other Ni-doped BFO systems. 12,13,24,25 Fig. 4 shows UV-vis transmittance spectra collected from the Ni-BFO lms annealed at 600 C. The transmittance depends on the Ni content.…”

Zinc‐Doped BiFeO3Nanoparticles: Synthesis, Characterization and Photocatalytic Activity on Acid Red‐85 Dye

“…[28] According to Dario et al, in a similar ABO 3 Perovskite crystal with doping there was a contraction in lattice parameters due to the additional oxygen vacancies created in the system, similar behaviour was also exhibited by zinc doping in BiFeO 3 . [37][38][39] In another study it is reported that doping 2 + ions in the Fe site creates anion vacancies or change the valence state of Fe which in turn leads to the introduction of oxygen vacancies. [40] Figure 2 depicts the results of XPS analysis of the 7.5BFZO sample (a, b, c, and d).…”

Novel optical properties and induced magnetic moments in Ru-doped hybrid improper ferroelectric Ca3Ti2O7

“…The XRD patterns of Ca 3 Ti 2 O 7 and Ca 3 Ti 1.9 Ru 0.1 O 7 after Rietveld refinement process using FULLPROF software are illustrated in Fig. 1(a) [21]. All peaks in the diffraction patterns could be matched perfectly with those of Ca 3 Ti 2 O 7 (space group A2 1 am (No.…”